Caribbean - Central America Weather

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
418 AM AST Sat Oct 24 2020

.SYNOPSIS...

Warm temperatures and below average rainfall is expected today. A
bit more moisture moves in for Sunday and Monday, then the middle
of next week looks quite moist across the region. There will be a
threat for urban and small stream flooding for especially Tuesday
through Thursday. Marine conditions are once again expected to
deteriorate due to brisk winds from the east. Small Craft Advisory
conditions will be met for the outer Atlantic waters beginning
tonight.

&&

.SHORT TERM...Today through Monday...

A surge of moisture accompanying a weak easterly perturbation
crossing the area this morning will continue to bring periods of
passing showers to the coastal waters and parts of the islands
from time to time. However, significant rainfall accumulations are
not expected over the land areas. Expect a gradual clearing
followed by mostly fair weather skies for the rest of the day,
except for some locally and diurnally induced afternoon convection
over parts of the interior and northwest sections of Puerto Rico.
Mostly sunny skies will prevail elsewhere including around the
U.S. Virgin Islands where limited or no shower activity is
expected for today. Slightly warmer daytime high temperatures are
also forecast for the north coastal areas under a prevailing
southeasterly wind flow.

Mid to upper level high pressure ridge will hold across the region
through the weekend, to maintain overall dry and stable conditions
aloft. Recent model guidance as well as satellite imagery and
derived water vapor products, all suggest a gradual drying trend for
the rest of today and through at least early Sunday, with the
layered precipitable water decreasing to less than 1.30 inches
today. Tropical moisture is forecast to gradually return by Sunday
afternoon and into Monday along with increasing trade winds, due to
the surface high pressure ridge building north of the region across
the west central Atlantic. This overall expected scenario should
increase the chance for more frequent early morning passing showers,
as well as the chance for shower development in and around the
islands. Afternoon showers and isolated thunderstorm development can
therefore be expected across portions of the interior sections of
Puerto Rico, with the heaviest rainfall focused on the western
interior sections of the island. As the prevailing winds increase,
expect the afternoon shower activity to quickly stream westwards
over the surrounding municipalities and towards the coastal waters.
Some entrainment of shower activity will be possible in isolated
areas over the west interior and this may lead to minor urban
flooding or ponding of water on roadways and in poor drainage areas
with the heavy rains. The U.S. Virgin Islands can expect overall
mostly fair weather conditions through Monday except for periods of a
few passing early morning and isolated afternoon showers.

.LONG TERM...Tuesday through Sunday...

For the middle of the week, leftover moisture from an old
tropical wave will move into our region. The highest moisture
content will arrive on Wednesday, yet Tuesday and Thursday will
also have plentiful above average moisture. At mid to upper
levels, high pressure will be to our west with a trough of low
pressure to our east and south. These conditions, along with
fairly average 500mb temperatures, don`t look particularly
favorable or disfavorable for thunderstorms, thus isolated
thunderstorms are probable. One limiting factor to shower activity
during this period is the strong high surface pressure to our
north and subsequent brisk low-level winds. These winds of around
20 to 25 mph at shower steering levels will keep showers moving
along quickly and thus limit rain accumulations. Still, isolated
areas of flooding are possible with persistent showers that
reform over the same area. Winds will generally be easterly to
east- southeasterly, so showers will be most likely for western
and northwestern Puerto Rico in the afternoons, and this is also
true for the San Juan Metro. At night, the eastern Puerto Rican
coast will likely see fast moving passing showers.

Heading into the weekend, there is a lot of uncertainty in the long-
range models. Friday generally looks drier in both the European
and GFS models. However, the weekend is a tricky forecast at this
point, since we will be right on the gradient of low moisture to
our north and high moisture to our south. At this point, the
European model seems to put more moisture over us for the weekend
compared to the GFS, but subsequent model runs the next few days
will shed more light on the details of the next weekend forecast.

&&

.AVIATION...

VFR conds will prevail at all terminals durg prd. SCT lyrs nr
FL025...FL050. Mstly isold SHRA en route btw islands and ovr
regional waters. VCSH at TJSJ/TJPS/TIST/TISX til 24/14Z. SFC wnds
calm to lgt/vrb bcmg mainly ESE at 10 to 15 kt after 24/14z. SHRA
mainly ovr interior sections of PR with isold TSRA psbl fm 24/17Z-
24/22Z. No other sig operational wx impacts anticipated durg prd.

&&

.MARINE...

Small craft operators should exercise caution today due to winds
above 15 knots and seas above 4 feet, though seas will remain at
6 feet or less through today. Then, confused seas due to a
weakening northerly swell generated by the distant Hurricane Epsilon
and a wind surge will create rough seas up to 8 feet across the
Atlantic Offshore waters. Therefore, a Small Craft Advisory is in
effect for the Atlantic Offshore waters from this evening through
at least Sunday. Other regional waters will likely see Advisory
conditions next week.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 92 78 90 78 / 20 20 30 30
STT 89 80 89 78 / 10 30 30 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
443 AM AST Sun Oct 25 2020

.SYNOPSIS...

Today is expected to be similar to yesterday, with below average
rainfall amounts and plenty of sunshine. However, we will trend
toward wetter conditions this week as moisture streams in from
the east. Wednesday and Thursday look particularly wet, with
showers for eastern Puerto Rico in the mornings and western Puerto
Rico in the afternoons. Rough seas are expected for the next
several days, primarily due to brisk winds from the east.

&&

.SHORT TERM...

Mostly clear to partly cloudy skies prevailed overnight with a few
passing showers noted moving over the coastal waters and reaching
parts of the east coastal sections of Puerto Rico. Expect a gradual
clearing and sunny skies by early morning, followed by mostly
fair weather skies across most of the region during the rest of
the day. Some locally and diurnally induced afternoon convection
will however be possible over parts of the interior and west
sections of Puerto Rico. Significant and widespread rainfall
accumulations are so far not anticipated in those areas. Mostly
sunny skies will prevail elsewhere including around the U.S.
Virgin Islands where limited shower activity is expected for today
and should be mostly on the west end and just downwind of the
islands. Slightly warmer than normal daytime high temperatures are
again forecast for the north coastal areas today under a
prevailing east southeast wind flow.

Mid to upper level high pressure ridge will hold across the region
today but will shift farther west Monday through Tuesday as an upper
trough /TUTT east of the area sinks further southwards while becoming
amplified over the northeastern Caribbean. In the meantime overall
dry and stable conditions will be maintained aloft. Model guidance
as well as satellite imagery and derived water vapor products, all
suggest an overall dry airmass in place today except for some
shallow patches of moisture moving across the region.

Afternoon showers and isolated thunderstorm development can
therefore be expected across the interior sections of Puerto Rico,
with the heaviest rainfall focused on the western interior sections
of the island. Expect afternoon shower activity to be short lived
and should quickly stream westwards leaving no significant rainfall
accumulations. However, strong shower activity will be possible in
isolated areas over the west interior. This may lead to ponding of
water on roadways and in poor drainage areas with the heavy rains.
The U.S. Virgin Islands can expect overall mostly sunny skies and
fair weather conditions today.

Tropical moisture transport is forecast to gradually return across
the region later this evening through Monday, along with increasing
trade winds as surface high pressure ridge builds north of the
region and a weak easterly wave crosses the area. This should
increase the chance for more frequent early morning passing showers,
as well as the chance for shower and isolated thunderstorm
development in and around the islands during the afternoon hours.

For Monday and Tuesday expected increasing moisture and instability
aloft as the upper ridge erodes and a tropical wave approaches the
eastern caribbean late Tuesday. This will increase the potential for
showers and thunderstorm development across the forecast area
resulting in better chance for urban and small stream flooding.

.LONG TERM...Wednesday through Monday...

Wednesday continues to look wet as a surge of moisture is expected
to arrive associated with an old tropical wave. The moisture will
arrive early in the morning which will likely kick off scattered
showers across the eastern Puerto Rican coastal areas and over the
USVI. Then in the afternoon, the showers will shift to western and
southwestern Puerto Rico under winds between 925 and 700 mb of
around 20 to 25 knots from the ENE. These brisk winds will cause
quick moving showers to help limit rain accumulations. Upper-level
conditions are a bit uncertain, since long-range models are showing
different solutions. However at this point, conditions do not look
overly favorable for strong thunderstorms, but isolated
thunderstorms are likely. This will be closely monitored however,
since there will be troughing at least in the vicinity that could
enhance activity for Wednesday.

Though long-range models seem to disagree about how the upper-level
conditions will play out, there does not appear to be any day in the
long term period where upper-level troughing would act to really
enhance activity. Furthermore, strong high surface pressure is
expected to continue in the central Atlantic during the long term
period, which will keep brisk low-level winds in place to limit
rainfall accumulation. Plentiful moisture will still be in place
for Thursday and Friday with winds more from the ESE, which will
produce showers and isolated thunderstorms for northwestern PR in
the afternoon. Scattered showers are possible in the overnight and
morning hours for both days. Heading into the next weekend,
models again disagree on how wet those days will be. It appears we
will be near a gradient of high moisture to our south and dry air
to our north, thus it is difficult this far out to determine the
weather for those days.

&&

.AVIATION...

VFR conds expected at all TAF sites durg prd. Sfc winds
lgt/vrb bcmg E-SE 10-18 kt with ocnl hir gusts and sea breeze
variations aft 25/14Z. Sct SHRA/Isold TSRA ovr W interior PR and
VCTY TJMZ/TJBQ 25/17Z-25/22Z. Isold SHRA ovr regional waters and en
route btw local islands til 25/12Z. L/lvl wnds fm E_SE 15-20 kts BLO
FL150 bcmg fm N and incr w/ht ABV. Max winds fm NNW-N 35-50 kt btw
FL350-480.

&&

.MARINE...

Another northerly swell is expected to arrive today, along with
easterly winds up to 20 knots across the region, so small craft
operators are urged to exercise caution. The winds will also
produce a wind driven swell and lead to confused seas. So far
forecast models have overestimated the wave heights for this
event, so the start time for the recently advertised Small Craft
Advisory for the outer Atlantic Waters has been pushed back until
later this evening. Though the northerly swell will back off by
Tuesday, moderate to fresh easterly winds will continue to produce
rough seas for most of this week.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 79 89 77 / 30 40 30 60
STT 89 79 88 78 / 30 40 30 60

[cycloneye]

Area Forecast Discussion...CORRECTED
National Weather Service San Juan PR
503 AM AST Mon Oct 26 2020

.SYNOPSIS...

Mid to upper level high pressure ridge will remain in place across
the region to maintain fairly stable conditions aloft at least
until Tuesday. Surface high pressure spread across the western
and central Atlantic will maintain a fairly tight pressure gradient
across the region, resulting in moderate to strong easterly winds
today into Tuesday. A weakly induced easterly perturbation will
cross the forecast area later tonight through Tuesday bringing
another surge of low level moisture to the region. The next tropical
wave is forecast to enter and cross the eastern Caribbean Wednesday
through Thursday, with a drier airmass and improving weather conditions
so for forecast by Friday and into the following weekend.

&&

.SHORT TERM...Today through Wednesday...
Drier air is now filtering into the region after a patch of moisture
passed through overnight. Precipitable water values of around 1.3 to
1.6 are expected throughout the day today, which is below average
yet sufficient to produce showers later this afternoon. Low level
winds will be out of the east to east-northeast, so showers in the
afternoon will develop in western to southwestern Puerto Rico. Winds
at shower-steering levels will be fairly fast, at around 20 to 25
knots, so the showers will move quickly and be blown offshore over
the coastal waters of western Puerto Rico. Upper level conditions do
not appear particularly favorable for strong thunderstorms, yet some
lightning strikes are possible this afternoon with the most vigorous
showers.

Over the next few days, low pressure at upper levels will move into
the region from the east on Tuesday and Wednesday. Forecast models
suggest it will stay to our east on Tuesday, which would be
unfavorable for thunderstorms. The low is then forecast to move
closer to the area for Wednesday, where 500mb temperatures cool to
around -7C. The positioning of the low and its associated trough is
important for the thunderstorm threat on Wednesday, and models do
not completely agree yet on its location. Yet generally speaking,
models suggest there will be some degree of troughing for Wednesday
over the region which would be favorable for thunderstorm activity.

At low levels, a fairly deep perturbation of moisture induced by the
upper level low is expected to arrive for Tuesday. The moisture will
arrive in the morning, so scattered showers can be expected for the
eastern Puerto Rican coastal areas, along with the USVI. These
showers ought to move quickly given the brisk low-level winds.
Though atmospheric conditions will not be favorable for
thunderstorms, isolated thunderstorms will still be possible in the
afternoon. Winds will generally be easterly to east-southeasterly,
so showers will converge over western to northwestern Puerto Rico in
the afternoon. Patches of moisture will continue to stream in
overnight Tuesday and into Wednesday, resulting in more scattered
showers for eastern PR and the USVI. A tropical wave will arrive on
Wednesday, and with improved upper-level conditions, thunderstorms
are possible across the region as it moves through. Models at this
point do not agree on the exact placement of the best moisture for
Wednesday, but there should be plenty to induce thunderstorms across
the region during the daytime.

.LONG TERM...Thursday through Tuesday...

Thursday and Friday is still forecast to remain fairly active and
unstable due to the proximity of an upper trough and associated
area of low pressure, as well as moisture accompanying and trailing
the tropical wave. Therefore expect a fairly wet weather pattern
with good potential for enhanced showers and thunderstorm
development across the islands and coastal waters especially on
Thursday, then gradually improving on Friday. Winds will become
more from the ESE, which will steer the showers and isolated
thunderstorms over the northwestern sections of PR during the
afternoon hours. Periods of Scattered showers will remain possible
across the coastal waters during the overnight and morning hours
through Friday. For the following weekend, so far expect an
improvement in the overall weather conditions as low level moisture
erodes and mid to upper level ridge builds in across the region.
Regardless, expect lesser frequent passing morning showers during
the overnight hours, followed by isolated to scattered locally
and diurnally afternoon convection over the weekend and into the
early part of the next work-week.


&&

.AVIATION...VFR conds expected at all terminals. However, occasionally
fast moving SHRA at times could produce VCSH across E. PR, USVI,
and Leeward Islands terminals. SHRA and isolated TS possible across
western PR between 26/16z and 26/22z, affecting the vicinity of
TJMZ. Winds around 5 to 10 kts till 14z, increasing to 10 to 20
kts from the ENE with gusts to near 25 kts at times with sea
breeze variations thru 23z.

&&

.MARINE...Recent data from the northern buoys 41043 suggest seas
between 8 to 9 feet at 13 secs while the San Juan buoy continued
to slowly increase to near 6 feet at 13 secs. This is due to the
northerly swell generated from distant Tropical Storm Epsilon,
located over the north- central Atlantic. This swell will continue
to arrive and spread over the local waters today. This along with
the moderate to fresh tradewinds, will cause choppy and hazardous
seas seas of up to 8 feet across most of the local waters.Breaking
wave heights of up to 12 feet can be expected across the northern
coast of Puerto Rico and Culebra. Small craft advisories are in
effect for most of the local waters. High surf advisory is in
effect for the northern beaches of Puerto Rico and Culebra and
continuing through early Tuesday. High Rip Current Risk is also in
effect for most of the northern beaches of the islands as well the
eastern beaches of St Croix.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 77 89 78 / 30 60 60 50
STT 89 79 87 78 / 30 60 60 50

[cycloneye]

Area Forecast Discussion...CORRECTED
National Weather Service San Juan PR
431 AM AST Tue Oct 27 2020

.SYNOPSIS...
An easterly disturbance will continue to move across the forecast
area today. This will result in an increase in low level moisture
and consequently more frequent passing early morning showers,
which will be enhanced by the upper trough/Tutt located just east
of the area. By mid-week, conditions are expected to become even
more favorable for showers and thunderstorm development due to the
repositioning of the upper level trough and associated area of low
pressure as well as an approaching tropical wave. This fairly moist
and unstable weather pattern will result in unsettled weather conditions
which is so far forecast to linger through the end of the workweek.

&&

.SHORT TERM...Today through Thursday...

The upper level atmospheric pattern will play an important role in
our weather for the next few days. During the past 48 hours, an
upper level low has developed to our east, just east of the Leeward
Islands. This low helped to induce and enhance a low level
disturbance with high moisture content that is currently impacting
the region. With precipitable water values around 2 inches, this
disturbance is producing scattered showers and isolated
thunderstorms across the local waters, the eastern Puerto Rico
coastal areas, and the USVI. By this afternoon, this moisture will
help to kick of showers and isolated thunderstorms across western
Puerto Rico and possibly the San Juan Metro area as well. With the
upper level low still to our east by this afternoon, it is not in a
favorable location to enhance thunderstorm activity, but some
lightning is possible this afternoon with near average lapse rates
and 500mb temperatures around -6C. With strong high surface pressure
over the central Atlantic, vigorous low-level winds will help
showers to move quickly and reduce their impacts. Still, with ample
moisture in place, there will still be a threat for isolated areas
of flooding, most likely in western Puerto Rico this afternoon for
the municipalities around Anasco. Finally, for the more vigorous
showers that form, gusty winds at around 30 mph are possible.

Over the past several days, a tropical wave has been moving across
the Atlantic towards our region, almost catching up to the
aforementioned low-level disturbance. By late tonight and tomorrow
morning, there will only be a small break between the disturbance
and the tropical wave. Thus the overnight hours tonight will see
showers exiting to our west as the disturbance moves out of our
region, followed by brief tranquil conditions with only isolated
showers before the tropical wave arrives late in the day tomorrow.
At this point, it appears the moisture from the wave will move to
our north Wednesday morning and not move over the USVI and
especially PR until later Wednesday night. Still, there will be
sufficient moisture to produce showers over southwestern Puerto Rico
Wednesday afternoon. Furthermore, the aforementioned upper-level low
will be just to our north by Wednesday afternoon, and in a better
position to enhance thunderstorm activity across the region. As the
upper-level low moves to our west overnight, and better moisture
moves in from the tropical wave, scattered showers and isolated
thunderstorms are expected overnight and through Thursday. Gusty
winds around 30 mph can again be expected with these showers. Decent
rainfall amounts can be expected for eastern Puerto Rico overnight
Wednesday and Thursday during the day. Though northwestern Puerto
Rico can also expect showers Thursday afternoon, cloud cover and
vigorous low-level winds may limit the impacts of these showers.

.LONG TERM...Friday through Wednesday...

Friday is still forecast to remain fairly active and unstable due to
the proximity of an upper trough just west of the area and moisture
trailing a tropical wave. These conditions will favor good potential
for enhanced showers and thunderstorm development over eastern
Puerto Rico and the USVI during the overnight and early morning
hours, then over portions of the central interior and northwest
sections of Puerto Rico during the afternoon. Meanwhile activity
over the U.S. Virgin Islands should gradually taper off during the
day with lesser chance afternoon convection expected. Winds will
become more from the ESE, which will steer the shower activity
over the northwestern sections of the islands during the afternoon
hours. Overnight and early morning passing showers will remain
possible over the coastal waters through Saturday with a gradual
drying trend by Saturday afternoon into Sunday. Expect continued
improvement in the overall weather pattern for the rest of the
weekend as a high pressure ridge will build across the region and
low level moisture transport erodes as a drier airmass filters in
and lingers across the region at least until Tuesday. By
Wednesday, another surge in trade wind moisture is so far forecast
as the tradewinds increase and a weak easterly disturbance
approaches the forecast area. By then expect a better chance for
overnight and early morning passing showers, followed by afternoon
convection across the islands and coastal waters.

&&

.AVIATION...
Mostly VFR conds expected at all terminals. However, fast moving
scattered showers could produce SHRA and VCTS for
TISX/TIST/TJSJ/TNCM/TKPK during the period, plus TJMZ/TJBQ in
afternoon. SHRA will have gusty winds around 25 to 30 kts.
Otherwise, winds easterly around 10 kts through 14z, then 10 to 20
kts from the E to ESE through 22z with sea breeze variations, then
around 10 kts after 22z.

&&

.MARINE...Confused seas will continue to produce hazardous marine and
surf zone conditions across portions of the local island through
much of the forecast period. Mariners can expect seas between 5 to
8 and winds around 20 knots with higher gusts. Therefore Small
craft advisories are in effect for much of the local waters. The
best marine conditions or the safest areas are along the southern
beaches and coasts of the islands. However, mariners should
continue to exercise caution due to winds around 20 kts and
occasionally higher gusts.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 79 86 77 / 60 30 50 60
STT 88 78 87 79 / 60 40 50 60

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
528 AM AST Thu Oct 29 2020

.SYNOPSIS...

Active weather conditions will persist across the area today. A
tropical wave is making its way through the area; widespread showers
were seen overnight, and they are expected to continue. There is an
increasing risk for urban and small stream flooding today through
tomorrow, especially in eastern and southern Puerto Rico, and the
U.S. Virgin Islands, as the moist east to southeasterly wind flow
persists. Relatively breezy conditions are also forecast to last
into the weekend, as well; strong gusts are also possible with
thunderstorms. Drying is expected Saturday, and a calmer pattern
will settle in for the first half of next week.

&&

.SHORT TERM...Today through Saturday...

Showers embedded in the flow coming around a tropical wave moving
through the area brought rain to the U.S. Virgin Islands, the
eastern third of Puerto Rico and parts of the southern coast. Most
of the heaviest rain, however, was in the local waters of Puerto
Rico both north and south. Over land, the heaviest rain amounts
ranged from one half to one inch on the eastern slopes of the
eastern mountains.

The tropical wave will move into Hispaniola later today. Low
pressure in the lower levels has also regenerated under strong
convection just east of 13 degrees north latitude 60 degrees west
longitude. This is expected to move west northwest and into the
central Caribbean by Saturday. The passage of the tropical wave and
low pressure to the south will bring drier air to the area on
Saturday although lingering moisture is still expected to be able to
spawn showers over interior and western Puerto Rico during the
afternoon.

In the meantime, the best moisture will pass over the the local
area this afternoon through Friday afternoon. A weak TUTT will
develop a low over Hispaniola this afternoon as it moves
northwest, and, in the process, moderate upper level divergence
will form over eastern Puerto Rico this afternoon to enhance
showers and possible thunderstorm development. This will make
urban and small stream flooding over the area likely. Upper level
divergence will also drift out of the southeast to affect
southwest Puerto Rico on Friday giving an additional boost to
showers and thunderstorms in the west and northwest as low level
flow shifts to the southeast. Low level winds, however tend to
increase during the period, causing the showers that form in
generally drier air on Saturday to leave less rain in any given
spot.

Some showers are expected overnight tonight and late Friday in
the U.S. Virgin Islands when showers favor the local waters.

.LONG TERM...Sunday through Friday...

A generally dry trend continues for the first half of next week. Mid-
to upper-level ridging will also lead to fairly stable conditions
aloft during that time. This will inhibit shower activity, and
thunderstorms are not likely. Moisture in the lower levels will
still likely combine with local effects and daytime heating to bring
afternoon showers to the area, especially in western Puerto Rico.
Gradual increases in humidity are expected by midweek, with patches
of moisture carried in, embedded in the trade winds. It is also
worth noting that an area of significant moisture will be relatively
nearby; this is associated with the area of interest discussed in
the Tropical Weather Outlook from the National Hurricane Center.
With the disturbance, which will likely be well to our southwest,
remaining more to the south, the moisture being pulled into it will
also likely be to the south, enough that it is not currently
expected to affect the area. However, this also means that a
relatively minor change in what happens with that system and any
potential development that occurs with it could have significant
impacts on the area. This would largely be in the form of how much
moisture is available to support shower activity.

On Thursday, significant increases in moisture are expected. A
perturbation and the remnants of an old, decayed frontal boundary
are forecast to push into the area from the east and north,
respectively. At the same time, the ridging aloft will be weakening,
with a mid-level trough strengthening and extending into the area
from the north. Decreasing stability is anticipated. Deepening
moisture is expected Thursday afternoon into Friday. An increase in
shower activity is anticipated; afternoon thunderstorms are also
increasingly likely.

&&

.AVIATION...

SHRA will move3 over and around TJSJ/TIST/TISX/TNCM/TKPK
for much of the day today. SHRA are expected to spread into
TJPS/TJMZ/TJBQ aft 29/15Z. These SHRA will bring brief MVFR conds
and mtn obscurations. Sfc winds will incr aft 29/13Z to bcm E-ESE 10-
20 kt with weak sea breeze influences and gusts psbl to 33 kt. Max
winds SW 25-30 kt btwn FL380-410.

&&

.MARINE...

Moderate to fresh trade winds are persisting across the local
waters; speeds of up to around 21 to 22 knots are possible, with
stronger gusts likely, especially near showers and thunderstorms.
Even as the lingering swell continues to fade, conditions will
remain choppy to hazardous due to wind-generated waves. In the
offshore Atlantic waters and Anegada Passage, hazardous conditions
will continue at least into the weekend. Small Craft Advisories
remain in effect.

At the local beaches, there is a high risk of rip currents for
beaches along the northern coast of Puerto Rico, as well as for
beaches of eastern St. Croix. There is a moderate risk of rip
currents at most other local beaches, except southwestern and
portions of southern Puerto Rico.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 86 77 88 77 / 80 50 60 70
STT 87 79 87 78 / 70 60 60 60

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
509 AM AST Fri Oct 30 2020

.SYNOPSIS...

Deep moisture persists across the area, bringing another day of
relatively active weather to the area. Drying is expected tomorrow
into the start of next week. Calmer weather will prevail, though
afternoon showers remain likely. Moderate to fresh tradewinds are
bringing choppy to hazardous marine conditions to most of the local
waters through the weekend, with seas of up to 8 feet possible.

&&

.SHORT TERM...Today through Sunday...

Deep moisture continues across the forecast area, the eastern
Caribbean and the Lesser Antilles. The heaviest convection is now in
the far southeastern Caribbean Sea and moving slowly westward in the
northeastern quadrant of low pressure over the northern coast of
Venezuela, but small cores of moderate and heavy rain are moving
west northwest over the the local waters of Puerto Rico. Activity
has subsided around the U.S. Virgin Islands for the moment.
Precipitable water in this area continues to range from 2.0-2.5
inches. High pressure at the surface will continue to stretch across
the Atlantic Ocean between 25 and 30 degrees north and this will
cause easterly winds to increase today and Saturday.

At 250 mb, high pressure east of Florida moved east and crossed
north of a low pressure over Haiti moving west. By this afternoon
the high will be north of the Leeward Islands and the low will be on
the south coast of Central Cuba. On Saturday and Sunday the High
will move southwest across the Dominican Republic.

The GFS is forecasting drier air to move into the forecast area
overnight tonight, but patches of moisture in the lower levels move
across the area at 850 mb. This will reduce but not eliminate
showers across the area, so some isolated thunderstorms may be
possible across western interior Puerto Rico on Saturday.

On Sunday a weak trough moves through the area with better moisture
behind it late in the day. This will bring a chance of
thunderstorms to Saint Croix but will likely be too late for Puerto
Rico.

.LONG TERM...Monday through Saturday...

Model guidance has shifted moisture and a tropical disturbance
slightly northward for the start of the next workweek today compared
to yesterday. The disturbance in question is the low being monitored
by the National Hurricane Center, as discussed in the Tropical
Weather Outlook, with a medium to high potential for forming a
tropical cyclone in the next two to five days. This has pushed
moisture northward enough to extend into portions of the area. The
result of this suggests that part of the region will be in drier
than normal air, with near-normal moisture in part of the southern
and western portions of the region. Mid- to upper-level ridging will
keep the environment less favorable for convection, and
thunderstorms are unlikely. However, the combination of moisture and
local effects will likely lead to some afternoon showers, especially
in western Puerto Rico.

Relatively dry, stable conditions are forecast for Tuesday and
Wednesday. Ridging persists aloft, and moisture is expected to
decrease across the area. Patches of moisture are still possible,
which will aid in the development of afternoon showers due to sea
breeze convergence. On the whole, though, the precipitable water
values are forecast to be significantly below normal, and even in
the patches of moisture, the precipitable water values will likely
only approach the lower end of normal. There is higher than normal
uncertainty with the forecast for the first half of next week. With
the potential development in the southwestern Caribbean, and its
effects on moisture levels for the region, a small change in the
forecast environment could yield substantial changes in expected
weather conditions for the area. While a dry pattern does look to be
much more likely at this time, the potential for the opposite
scenario is non-negligible.

On Thursday, a shift in the pattern is anticipated. Moisture will
begin to converge over the area. The disturbance over the Caribbean
appears poised to have a portion spin off and remain near the
region. Meanwhile, a frontal boundary from off of the mainland
United States will press towards the area as it decays. Though it is
forecast to remain to the north, it will help in the development of
this moisture convergence. Aloft, the mid- to upper-level ridge will
erode. Some troughing is expected at the mid-levels by late in the
day on Thursday, providing some instability. A deepening column of
moisture is forecast to develop over the area, bringing a
significant increase in shower activity. Moisture levels will
continue to gradually increase through Saturday. During this time,
increasing shower activity is anticipated, both with passing showers
during the overnight and morning hours, and afternoon convection.
Thunderstorms also become increasingly likely.

&&

.AVIATION...

VFR conds will prevail through arnd 16Z over PR, although ocnl
mtn obscurations are expected. Brief MVFR CIGs are psbl in TNCM.
Aft 30/16Z, SHRA will dvlp ovr and arnd PR with isold TSRA with
some MVFR CIGs/VSBYs. Easterly sfc winds will incrs aft 30/14Z to
12-18 kts with ocnl gusts to 25 kt expected nr heavy SHRA and alg
the nrn coast. Max winds E 20-25 kt btwn FL035-050 and FL170- 280.

&&

.MARINE...

Moderate to fresh trade winds continue across the area. Even as the
northerly swell fades, winds will be sufficient to maintain choppy
to hazardous conditions. Seas of up to 8 feet are possible across
much of the local waters through the weekend, especially the
offshore waters, both Caribbean and Atlantic, and the local
passages. Small Craft Advisories are in effect for most zones.

For the beachgoers... Rip currents remain a concern, with a high
risk of rip currents for the north coast of Puerto Rico, as well as
eastern beaches of St. Croix, and Culebrita. The risk will gradually
become moderate for northeastern and north central beaches of Puerto
Rico tonight and tomorrow, with the risk increasing and becoming
high for southeastern Puerto Rico tonight.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 77 89 77 / 50 50 40 40
STT 88 78 87 77 / 60 40 30 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
536 AM AST Sat Oct 31 2020

.SYNOPSIS...

Drier, more stable conditions are expected today compared to the
previous couple of days, as a relatively dry airmass is moving
over the area. An area of moisture pushing into the region will
likely bring a resurgence of showers for Sunday into Monday,
followed by a resumption of drier conditions. There will likely
remain sufficient moisture to allow for the development of showers
each afternoon, due to local effects and diurnal heating. Breezy
conditions continue, and choppy to hazardous marine conditions
persist across the local waters, with seas of up to 8 feet
possible.

&&

.SHORT TERM...Today through Monday.

A few thunderstorms occurred in the southern-most local Caribbean
waters before midnight, but otherwise showers began tapering off
over the local waters from east to west. Very light rain occurred
over high terrain in eastern Puerto Rico. Total precipitable water
products show drier air being advected into the area above a
persistently wet later below about 800 mb. Patches of moisture also
move through in the easterly flow today and Sunday that will cause
brief passing showers with very limited accumulations. A trough at
700 mb will move into the Caribbean Sea mostly south of 15 degrees
north, and spread moisture from the southeast across the area late
Sunday afternoon and overnight. This will bring considerable shower
activity to the eastern and southeastern portion of Puerto Rico
beginning late Sunday and continuing into Monday. Because mid levels
remain mostly dry then, heavy accumulations are not expected, but
spots of over one inch during the last 24 hours are expected--
mainly in eastern Puerto Rico.

At mid levels, high pressure continues northeast of the area and
extends over Puerto Rico and the U.S. Virgin Islands. At upper
levels, a similar situation exists, but the high shifts to the west
and fills the central and western Caribbean by Monday. This will
cause potential for thunderstorms to be quite limited during the
period.

The U.S. Virgin Islands will see some shower activity late in the
period but it will not be as pronounced.

The Saharan dust that was seen in the air on Friday will persist
through the period with the heaviest dust Sunday evening and will
also serve to limit shower activity during the period.

.LONG TERM...Tuesday through Sunday...

Drier air is expected to be over the region on Tuesday, though there
is the potential for some lingering moisture in the west, mostly
over water. Aloft, a mid-to upper-level ridge will persist,
providing stability. Because of these factors, shower activity is
likely to be inhibited, through at least Wednesday. There will
remain sufficient moisture in lower levels, though, especially as
patches of moisture are advected in on the trade winds, to allow for
the development of afternoon showers with sea breeze convergence.
Confidence in the forecast to this point is average.

A tropical wave has formed a low, and is located southwest of the
area. While no direct impacts are anticipated, this system, which
has a high chance for development into a tropical cyclone, will
likely have indirect impacts through much of the week next week. As
was mentioned in the previous AFD, small changes in the forecast
environment can yield significant alterations for conditions
locally. Model guidance suggest that the system will remain more to
the north for a time, before making its way towards Central America,
than with yesterday`s runs. The overall impact on the region of a
decaying frontal boundary is more limited in this scenario, and
moisture convergence is weakened and delayed. Thursday could be
drier than in previous forecasts, and that is reflected in this
morning`s forecast. The confidence in the forecast for Thursday is
low, and only declines from there. There is less agreement on the
fate of any potential system that develops following an interaction
with Honduras and Nicaragua. The GFS pushes the system northward,
heading for Cuba and Florida. However, consistency between runs
has been notably lacking. The ECMWF has a new low developing in
the same general area east of Central America, which then tracks
northeastward over eastern Cuba. This is also a fairly new
solution, as the prior runs had the low dissipating over Central
America with no new development following in its wake. Regardless
of the scenario, an increase in moisture for Friday through Sunday
is currently anticipated. But, the dynamics aloft are likely to
be significantly impacted by what any potential low might do and
where it might go. Should a low move northward toward Florida, it
will likely inhibit some of the erosion of a ridge aloft, as well
as the arrival or development of any troughing in the mid- to
upper-levels. Thunderstorms appear likely for any scenarios that
currently appear to be plausible; the highest potential would be
for western Puerto Rico during the afternoons. The steering flow
is also forecast to become lighter late in the week next week.
With showers moving more slowly across the region, there is a
higher potential for more vigorous development, as well as higher
rainfall amounts. But, at the risk of sounding like a broken
record, confidence in the forecast declines quite rapidly after
midweek next week. For now, though, Friday through the weekend
look to be shaping up to be active weather days.

&&

.AVIATION...

VFR conditions are expected at all TAF sites. Sct SHRA
are expected to dvlp aft 31/17Z ovr interior and wrn PR with mtn
obscurations. Saharan dust will limit visibilities to 9-15 SM. Sfc
winds 10-20 kt with gusts to 32 kt psbl nr the N and S coasts of PR.
Max winds E 20-25 kt btwn FL015-055 and FL140-200.

&&

.MARINE...

Moderate to fresh trade winds persist through the weekend across the
local waters. This will maintain choppy to hazardous marine
conditions for much of the region, likely at least into the start of
the next work week. Small Craft Advisories remain in place. It is
worth noting that uncertainties with the future of the disturbance
southwest of the area do negatively impact the confidence in this
forecast, as well.

For the beachgoers, there remains a high risk of rip currents at
northwestern beaches of Puerto Rico. There is also a high risk of
rip currents for eastern beaches of St. Croix, Culebra, and Vieques,
as well as beaches of southeastern and south central Puerto Rico.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 76 88 76 / 20 20 30 40
STT 87 77 87 77 / 10 20 20 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
512 AM AST Sun Nov 1 2020

.SYNOPSIS...

Relatively dry and stable weather conditions are expected today,
though afternoon showers are still possible. Tomorrow, moisture
associated with a tropical wave moving through the Caribbean will
make its way into the area, and an uptick in shower activity is
anticipated, though likely moderated by Saharan Dust over the area.
This is fairly quickly followed by a return to drier air Tuesday
through midweek. A more active weather pattern is currently forecast
for next weekend, but confidence in the forecast beyond midweek is
low.

&&

.SHORT TERM...Today through Tuesday...

Showers overnight were very minor and tended to stay offshore from
Puerto Rico. Several did cross the northeast coast, however, and
left up to four tenths of an inch along the foothills of the
Luquillo range. Shower activity is expected to be very minor today
with dry air now in place. A tropical wave is moving west northwest
through the windward islands and consistent with yesterdays model
runs, moisture is expected to move into the area around 01/22Z.
Hence a considerable uptick in shower activity is expected then.
Moisture will not be able to penetrate Puerto Rico very deeply
overnight tonight, but Monday should have some showers activity
across the entire island. Today, Saint Croix will be the first to
detect this surge is shower activity, and some chances of rain there
persist through at least Monday. Drier air follows the moisture
behind the tropical wave passage today and tonight and by Tuesday
morning precipitable water values are expected to be below 1.25
inches--but only briefly. Moisture recovers very quickly and reaches
1.9 inches by Tuesday evening.

With high pressure just north of the area at mid levels and
northwesterly flow over the area at upper levels due to high
pressure over the Caribbean, little in the mid and upper levels of
the atmosphere is found to enhance the showers born by the mostly
lower level moisture pulse that moves through tonight through Monday.

Saharan dust with peak dust concentrations on Monday morning is
expected, which will also serve as a limiting factor for shower
activity during the period.

.LONG TERM...Wednesday through Monday...

Dry air persists over the region on Wednesday. Aloft, a mid- to
upper-level ridge will continue to provide stability. Therefore,
conditions are not going to be conducive to convective development
and shower activity will be inhibited. However, there will remain
sufficient moisture in the low-levels to aid in the development of
some afternoon showers due to sea breeze convergence. The confidence
in the forecast up to this point is moderate to high. This does not
last, however.

Tropical Storm Eta is located more than 600 miles southwest of
Puerto Rico, moving away. This system is forecast to intensify;
there is good model agreement on expecting further development, as
well as tracking to Central America over the next few days, which
brings us through Wednesday. The most likely scenario for Eta is
landfall in Central America, likely somewhere around Honduras and
Nicaragua, as is reflected in the most recent forecast from the
National Hurricane Center. The majority of the model guidance
suggests that the system will move inland and weaken
significantly; from there, the tropical cyclone would likely
dissipate or maybe make its way into the Pacific. The GFS
continues to lack consistency between runs as well as much in the
way of support from the other models. Currently, it suggests less
opportunities for troughing to advect or develop in the mid- to
upper-levels late in the week, which could weaken support aloft
for convection; even so, it would bring significant deep moisture
over the area. For the ensemble GFS, the spread itself is fairly
vast, with an array of scenario options to choose from - crossing
Central America, heading north past the Yucatan Peninsula, and
even some ensemble members making their way northeast. A ridge
that is forecast to build into the western central Atlantic
between now and the second half of the week is likely to be strong
enough to keep this system from making any significant headway
towards the northeast. A series of synoptic systems over the
mainland US are likely to keep the system from making much
distance northwestward, either. The spread between ensemble
members also illustrates how sensitive the forecast is to any
relatively minor changes in the environment. So: while a scenario
in which Eta makes a bit of a U-turn over Central America cannot
be wholly ruled out, it being an outlier in model guidance, lack
of good consistency from run to run, large spread in the GFS
ensemble, and just all of the environmental factors that would
need to be -just so- do make this scenario not remarkably
plausible. What currently looks more likely, however, is for
another low to develop in the wake of Eta, over the western
Caribbean, after the system has weakened significantly or even
dissipated. Again it brings the potential inhibition of troughing
aloft that might otherwise occur over the area, though would be
less impactful than what is illustrated by the solution from the
GFS. This scenario has at least some support, in varying measures,
from the German (ICON) and Canadian (CMC) models, and is
currently the scenario given by the most recent run of the ECMWF.
Some troughing in the mid-levels would be likely by the end of the
week, supporting afternoon convection. And the one thing it seems
that the guidance model can very nearly agree on is that moisture
convergence is expected by the end of the week, likely by Friday,
leading to deep columns of increased moisture over the area. The
exact timing is subject to change, as well as the magnitude of
moisture advection and convergence.

To make a long story short (or shorter, anyway), though - the
current expectation for Thursday is slow increases in moisture,
though possibly remaining on the dry side of normal through the day.
More significant increases in moisture are forecast to arrive likely
by Friday, or possibly even early Saturday. Increasingly active
conditions, especially during the afternoons, are expected for next
weekend. Steering flow is also currently expected to subside late in
the week, which has the potential to bring more vigorous afternoon
showers and higher rainfall amounts. Confidence in the forecast for
increasing moisture over the area late in the week is low to
moderate. But confidence in the forecast dynamics is quite low,
associated with Tropical Storm Eta`s indirect impacts; as such,
the confidence in the forecast as a whole is low. Therefore, the
current forecast is fairly near to climatology.

&&

.AVIATION...

Hazy conditions with 9-15 SM visibilities will persist through the
period. A weak trop wav is moving thru the windward islands with sct
SHRA this morning and will apch TISX late this afternoon. In PR,SHRA
will be few and brief till aft 01/17Z, then sct SHRA expected ovr
nwrn and interior PR. VFR conds expected thru at least 17/00Z, but
mstr incrs aft 01/22Z TISX, and mtn obscurations will likely dvlp
aft 02/00Z in ern PR. Sfc winds bcmg 10-20 kt from the E with ocnl
gusts to 28 kt. Max winds W-NW 25-30 kt btwn FL400-495. Incrg aft
02/09Z.

&&

.MARINE...

Moderate to fresh winds continue across much of the local waters.
This will promote choppy to hazardous seas, especially in the
offshore waters and local passages. The hazardous conditions will
continue into late tomorrow or early on Tuesday. Small Craft
Advisories remain in effect. Wave heights could increase again late
in the day on Tuesday due to a combination of weak swell and
moderate to locally fresh winds in the offshore Atlantic waters.
Conditions during the day on Tuesday are very borderline for Small
Craft Advisory criteria, and so, for now, the Advisory currently
only extends into Tuesday morning.

For the beachgoers, there is a moderate risk of rip currents across
most local beaches. At beaches on the southern part of the west
coast of Puerto Rico, western beaches of St. Croix, and some beaches
of St. John, the risk of rip currents is low.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 77 88 76 / 50 60 60 30
STT 88 79 86 77 / 50 60 50 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
359 AM AST Tue Nov 3 2020

.SYNOPSIS...

Upper-level ridge will reestablish itself across the region this
evening into Wednesday. The surface high pressure ridge over the
Atlantic waters will promote strong easterly winds that will pull
patches of low-level moisture from time to time across the region.
Moisture is forecast to increase during the weekend and early next
week as a weak disturbance moves into the Caribbean waters.

&&

.SHORT TERM...Today through Thursday...

Scattered showers with isolated thunderstorms were noted early in
the morning hours across the Caribbean waters and the Mona Passage
as a moist layer lingered to the west/southwest of the region. A few
showers reached portions of southern Puerto Rico, with the highest
rainfall amounts staying just offshore of Ponce. For today, this
area of moisture is forecast to pull away as a drier air mass with
some small amounts of Saharan dust continues to filter from the
east. An upper level high pressure should continue to influence the
local weather conditions for the next day or two, and mostly fair
weather conditions should prevail across the islands, with the
exception of diurnally induced afternoon showers over western PR
with a brief isolated thunderstorm each day. Through the night
period, trade wind showers across the tropical Atlantic should move
from time to time across the U.S. Virgin Islands and the eastern
sections of PR, leaving mostly minor rainfall accumulations. For
Thursday, the upper level high pressure is expected to weaken and
this should allow for better vertical development of showers and
thunderstorm development along the Cordillera Central and western
PR. Seasonable temperatures will continue across the islands through
the short term period. East to southeast trades today will gradually
shift from the east to northeast by Thursday.

&&

.LONG TERM...Friday through Wednesday...

At the beginning of the period, patches of moisture embedded in the
easterly trades will move over the area from time to time. The
easterly wind flow will support the development of showers across
eastern Puerto Rico and adjacent eastern islands during the morning
hours and showers across the interior and western Puerto Rico during
the afternoon.

The GFS and EURO continue to show moisture content increasing each
day late in the period due to rich tropical moisture pooling over
the area from the southwest. There`s some consistency between the
GFS and EURO this weekend through early next week. The reliable
global models have deep tropical moisture building up in the western
Caribbean Saturday through the middle of the following week. As the
moisture increases throughout the western Caribbean waters, the
surface to mid-level winds will veer from the southwest and draw the
deep tropical moisture across portions of Puerto Rico on Monday
through the middle of the week. The increase in moisture will
increase the rain chances for Puerto Rico and adjacent islands.

Several factors could change the forecast above. The rich tropical
moisture and remnants of Hurricane Eta move into the eastern
Pacific due to the ridging holding over Florida and the western
Caribbean.

Due to the high uncertainty in the mid to upper-level pattern
evolution, Tropical cyclone Eta`s movement and how the low
moisture will progress eastward over the region.

FORECAST CONFIDENCE: LOW

&&

.AVIATION...

Mainly VFR conditions are expected to prevail across all
terminals. However, afternoon convection over west PR may cause
tempo MVFR across the western terminals. E-ESE winds will increase
from 10-15 kt aft 14z with sea breeze variations and higher gusts.

&&

.MARINE...

Moderate to locally fresh winds will promote choppy seas through
Wednesday. A northerly swell entered the local Atlantic waters
yesterday and increased seas over the outer Atlantic waters. The
outer buoy show seas ranging from 5 to 7 feet over the outer
Atlantic, and recent model guidance agrees with the observations.
A Small Craft Advisory in effect until 2 PM AST this afternoon
for the outer Atlantic waters. A second northerly swell is is
forecast to invade the Atlantic waters late Wednesday through
Thursday. There is a high risk of rip currents for the north-facing
beaches of Puerto Rico and Culebra.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 75 86 76 / 20 50 10 40
STT 86 77 87 77 / 20 50 30 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
409 AM AST Wed Nov 4 2020

.SYNOPSIS...

Fair weather conditions are expected to prevail across the local
area through Thursday. A mid to upper-level trough is forecast to
move near the area on Friday and create unstable weather
conditions. This weekend into early next week a unsettled weather
pattern is forecast as deep tropical moisture advects into the
area from the western Caribbean and eastern Atlantic waters.

&&

.SHORT TERM...Today through Friday...

Upper level high pressure will continue to remain as the main
weather feature through at least early Thursday. At low to mid
levels, a dry air mass with some amounts of Saharan dust will
continue to prevail today across the region. This should maintain
overall fair weather conditions across the islands through at
least Thursday. However, diurnally induced afternoon showers with
isolated thunderstorms are expected each day over portions of the
interior and western Puerto Rico. This activity may cause urban
and small stream flooding across these areas.

By late Thursday into Friday, a mid level trough is expected to move
from the north. This is expected to allow moisture to increase
across the region and provide more unstable conditions for shower
and thunderstorm development, mainly over mainland Puerto Rico and
downwind from the U.S. Virgin Islands in streamer type of shower
activity. Trade winds are forecast to decrease late in the short
term period, and some showers could be slow movers over sections of
central and western PR. Increasing the threat for urban and small
stream flooding.

.LONG TERM...Saturday through Thursday...

The GFS and EURO show a mid to upper-level low northwest of
Puerto Rico; the mid to upper-level will erode the trade wind cap
and allow moisture to filter into the area Friday through the
weekend with precipitable water hovering around 1.9 to 2.0 inches.
The moisture increase and local effects will promote the
development of showers across eastern Puerto Rico and adjacent
eastern islands during the morning and showers across the interior
and western Puerto Rico during the afternoon.

The global models continue to support deep tropicalmoisturebuilding
up in the western Caribbean Saturday and Sunday as a Tropical Storm
nears Cuba. As the tropical cyclone moves north, its tail will
move into the local area, as a tropical wave invades the local
waters from the southeast. The combination of the tropical storm`s
tail and the tropical wave moving into the local water will
increase showers and possibly thunderstorms over the region Sunday
through early next week.

I want to stress there is still uncertainty in how much low-level
moisture will move across the region. The Tropical storm`s
position and the mid to upper-level pattern will play a
significant role in Puerto Rico`s long-term weather. At this time,
guidance is trending to a wetter than normal pattern for the
long-term period.

FORECAST CONFIDENCE: Medium

&&

.AVIATION...

Mainly VFR conditions are expected to prevail across all
terminals during the next 24 hours. However, afternoon SHRA/TSRA
over western PR may cause tempo MVFR across the western terminals
from 18z-22z. East winds will increase from 10-15 kt aft 14z with
sea breeze variations and higher gusts.

&&

.MARINE...

A northerly swell will invade the outer Atlantic waters late this
evening and cause hazardous seas across the Atlantic waters. This
morning seas up to 6 feet for most of the local waters, with
easterly winds up to 15 kts with higher gusts. This afternoon a
Small Craft Advisory goes in effect for the outer Atlantic waters.
There is a high risk of rip currents for the north-facing beaches
of Puerto Rico and Culebra.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 86 76 87 77 / 20 40 30 40
STT 87 77 87 76 / 30 40 40 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
459 AM AST Thu Nov 5 2020

.SYNOPSIS...Upper level high pressure will continue to dominate
the local weather conditions today. An upper level trough will
gradually erode the high pressure and promote more unstable
conditions through the weekend. A further increase in low level
moisture and rainy weather is forecast through early next week. A
northerly swell will cause hazardous marine and rip current
conditions today.


&&

.SHORT TERM...Today through Saturday...

Upper-level high pressure that dominated the local weather will
begin to weaken later today as a mid to upper-level trough develops
over the central Atlantic waters. At low levels, a surface high
pressure over the western Atlantic is creating brisk easterly winds
across the forecast area. These winds will continue through the
afternoon across Puerto Rico and the U.S. Virgin Islands. GOES-16
satellite shows a patch of moisture with a precipitable water value
near 2.0 inches moving across eastern Puerto Rico this morning. The
moisture is inducing isolated to scattered showers, mainly over the
local waters and portions of eastern Puerto Rico. Later today,
isolated to scattered showers will develop over western Puerto Rico
due to local and diurnal effects. However, the brisk easterly winds
will cause showers that develop to scurry across western Puerto
Rico. However, minor flooding and ponding of water on roadways is
possible.

The mid to upper-level trough is forecast to deepen over the central
Atlantic waters and continue to weaken the trade wind cap early
Friday; and slowly moisten the mid to upper-level of the atmosphere
across the region. Guidance shows moisture content remaining above
2.0 inches Friday and Saturday. The increase in moisture content and
local and diurnal effects will promote an uptick in afternoon
convection on Friday and Saturday.

.LONG TERM...Sunday through Thursday...

Latest model guidance continues to suggest an unstable and wet
weather pattern through midweek next week across the region. Early
in the period, Tropical Depression Eta is forecast to redevelop
into a Tropical Storm and move over Cuba. While a weak surface
high pressure moves over the northwestern Atlantic and builds
across the north central Atlantic by the end of the long term
period. At upper levels, a trough pattern is expected to develop
mainly to our northeast. This expected weather pattern will cause
further weakness in the trade wind inversion and promote pooling
of tropical moisture across the forecast area in a light to
moderate southeasterly steering wind flow. Based on this,
diurnally induced afternoon showers and thunderstorms are expected
to develop each day over mainland PR, while isolated thunderstorm
development is possible across the regional waters through at
least early Wednesday. A drier air mass is forecast to move later
in the forecast period, and fair weather conditions should
prevail by Thursday.


&&

.AVIATION...VFR conds are expected through 05/17Z. VCSH across
eastern PR terminals and terminals of USVI through 05/22Z.
SHRA/TSRA over western PR may cause tempo MVFR across the western
terminals from 18Z-22Z. Sfc winds Lgt/Vrb bcmg fm E 10-20 kts with
higher gusts possible.


&&

.MARINE...Northerly swell will cause seas to range between 5-8
feet, with the highest seas expected across the offshore Atlantic
waters. Small Craft Advisories are in effect for the northern and
eastern waters of the islands. Breezy trades will continue between
15-20 knots. The swell will also cause breaking wave action along
the northern beaches of the islands, and a High Rip Current Risk
is in effect for the northern beaches of PR, Culebra and St.
Thomas. Marine conditions will gradually improve during the
weekend.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 85 75 86 75 / 30 40 50 40
STT 87 76 85 76 / 50 50 50 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
420 AM AST Sun Nov 8 2020

.SYNOPSIS...An unsettled weather pattern is expected to prevail
through the middle of the week as very deep tropical moisture
pulled up from Tropical Storm Eta moves over the area. This will
result in favorable conditions for periods of enhanced rainfall
activity. Improving weather conditions expected by the second of
the week and into the first half of next weekend as a drier air
mass moves overhead.

&&

.SHORT TERM...Today through Tuesday...

Tropical Storm Eta -which is located west of the forecast area- will
continue to pull a deep plume of tropical moisture across the local
islands. Based on the GFS guidance, the precipitable water content
associated with the aformentioned plume of moisture is expected to
exceed 2.3 inches by this evening. In addition to the deep tropical
moisture across the forecast area, the environmental conditions are
expected to become more favorable with a layer of convective instability
prevailing across the local islands through at least midweek. This
evolving pattern will assure passing showers across the eastern
coastal areas of Puerto Rico and the outlying islands as well as
afternoon convection across northwest Puerto Rico today. The intensity
and areal coverage of showers and thunderstorms, however, are expected
to increase Monday and Tuesday. As a result, expect morning showers and
thunderstorms across the US Virgin Islands and eastern Puerto Rico,
spreading across central and western portions of Puerto Rico by midday,
both days. This is resulting in an increasing risk for urban and small
stream flooding through at least midweek. Soils are already saturated,
therfore, mudslides and river flooding particularly across eastern Puerto
Rico and portions of the western interior are possible as well. At this
time, there is a potential for rainfall accumulations to exceed 3-4 inches
across east Puerto Rico. Elsewhere, the potential exists for rainfall
totals to exceed 2-3 inches.

.LONG TERM...Wednesday through Sunday...

Weather conditions will continue to remain unsettled on Wednesday
as deep tropical moisture will linger across the area. Therefore,
periods of enhanced shower and thunderstorm activity can be
expected with the heaviest activity expected across the eastern
half of Puerto Rico and the USVI during the morning hours followed
by additional activity across western Puerto Rico during late
morning into the afternoon hours. Urban and small stream flooding
as well as river flooding and mudslides in areas of steep terrain
will continue to be a threat. A surface high pressure over the
western and central Atlantic will then advect a drier air mass
into the region by late Wednesday afternoon into Wednesday night.
Therefore, improving weather conditions can be expected during
this time period.

More tranquil weather conditions still expected Thursday through
Saturday as the aformentioned dry air mass will prevail. Patches
of low-level moisture embedded within the easterly trade wind
flow, however, will move across the area from time to time. This
will result in some passing showers across portions of eastern PR
and the USVI during the overnight and early morning hours followed
by the development of some afternoon convection across western
Puerto Rico. Rainfall accumulations for the most part should
remain limited. Breezy conditions are also expected as the
aformentioned surface high pressure will tighten the local
pressure gradient. Winds will be the strongest Thursday and
Friday.

The weather pattern looks to turn more unsettled by the end of
the long term period due to a mid to upper-level low moving over
the area. This will induce a low-level trough, which will advect
deeper moisture into the area from the southeast. Therefore, if
model guidance is correct with its current solution, an increase
in shower and thunderstorm activity can be expected.

&&

.AVIATION...Mostly VFR conds are expected to prevail at all TAF
sites with VCSH possible at PR and USVI terminals. Aft 08/17z
SHRA/TSRA development is expected in and around TJBQ/TJMZ. Sfc winds
less than 10 kt early this morning, becoming ESE 10-15 kt aft 08/14Z
with some sea breeze variations.

&&

.MARINE...Seas of between 3 and 6 feet will generally prevail
across the local waters through Monday, with the highest seas
expected across the offshore Atlantic waters. Seas are expected to
increase Monday night into Tuesday as winds increase due to a
surface high pressure building across the western and central
Atlantic. Choppy to hazardous seas are expected across the
regional waters by then and look to prevail through the end of the
work week. Small Craft Advisories are likely across portions of
the local waters. A moderate risk of rip currents will continue
across the north and east-facing beaches of the islands for today.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 76 86 75 / 50 50 60 60
STT 85 76 86 76 / 60 60 60 70

[cycloneye]

AFDSJU

Area Forecast Discussion...CORRECTED
National Weather Service San Juan PR
506 AM AST Mon Nov 9 2020

.SYNOPSIS...Unstable weather conditions along with abundant
tropical moisture will cause periods of heavy rainfall through
midweek. Saturated soils and rainy weather will result in a high
potential for flash flooding and mudslides across the local
islands. Therefore, a Flash Flood Watch has been issued.

&&

.SHORT TERM...Today through Wednesday...

A very unsettled weather pattern is expected through the
short-term period. Tropical Storm Eta, currently located near
the Florida Keys, is pulling up a very deep plume of moisture
across the forecast area with precipitable water values expected
to range between 2.2 and 2.5 inches throughout the period, which
is near the 99 percentile for this time of the year. As a result,
the environment is very favorable for enhanced rainfall activity
to occur. Scattered to numerous showers and a few thunderstorms
are expected across portions of eastern Puerto Rico and the USVI
this morning, extending into western and northwestern portions of
Puerto Rico during the afternoon hours. Tuesday and Wednesday will
have more significant rainfall activity as a tropical wave,
currently located near the Lesser Antilles, will get drawn up by
the moisture plume from Eta. At this time, there is the potential
for rainfall accumulations of up to 2 inches for today and up to
3-4 inches each day for Tuesday and Wednesday across eastern
Puerto Rico and the U.S. Virgin Islands. Across western Puerto
Rico, the potential exists for rainfall totals of between 1 and 2
inches each day.

The heavy rainfall activity from Sunday produced widespread
accumulations between 2 and 5 inches with isolated amounts of up
to 8 inches across the southern and eastern third of Puerto Rico.
Therefore, the terrain is very saturated and the streamflows along
rivers and streams are running well-above normal. Given the
significant rainfall activity forecast through Wednesday, flooding
and mudslides will be a major concern. Therefore, a Flash Flood
Watch has been issued for the entire forecast area through
Wednesday evening as any prolonged period of heavy rainfall
activity will have the potential to create flash flooding, some of
which may be significant.

.LONG TERM...Thursday through Tuesday...

Although the ECMWF is more aggressive with a rapid erosion of
moisture by Thursday evening, precipitable water values are still
expected to range above normal values. With this moisture prevailing
over the area, still expect periods of showers across the local
islands throught the day on Thursday, particularly across east
Puerto Rico and the US Virgin Islands. A seasonal weather pattern
is then expected Friday through Sunday under a much drier air
mass. The precipitable water content is expected to range between
1.20 and 1.40 inches. However, this is enough to combine with
local effects and diurnal heating to result in a few afternoon
showers across the interior and western portions of Puerto Rico
each day. Some passing showers across portions of northeast PR
and the USVI during the overnight and early morning hours cannot
be ruled out under an east to east northeast wind flow.

The chance for organized convection is expected to increase by
the end of the forecast cycle as an upper level low approaches
the local islands from the northeast. This feature will promote
moisture advection late Monday and Tuesday. If model guidance is
correct with its current solution, another round of unsettled
weather conditions is expected early the next workweek.

&&

.AVIATION...SHRA activity surrounding the local waters will cause
VCSH across the terminals through 09/14z. Afterwards, activity is
expected to develop over land, mainly over PR through 09/22z. This
will result in VCTS across TJBQ and VCSH elsewhere. MVFR conditions
may occur, especially if the activity moves over the terminal sites.
Abundant cloud cover will cause BKN ceilings between FL050-080, but
could lower with any SHRA activity. Winds will be light and variable
through 09/12z, increasing to between 10-15 kts from the E-ESE after
09/14z, with some sea breeze variations.


&&

.MARINE...A moderate to locally fresh easterly wind flow will continue
for the next few days. A small northeasterly swell will move across
the Atlantic waters today. As a result, choppy to hazardous seas
up to 7 feet are expected today, but building up to 8 feet by
Tuesday morning mainly across the Atlantic offshore waters and the
Anegada passage. As a result, there is a Small Craft Advisory in
effect from this evening onwards.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 85 74 85 74 / 70 80 80 70
STT 86 75 86 75 / 70 80 70 70

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
435 AM AST Tue Nov 10 2020

.SYNOPSIS...A very unsettled weather pattern is expected during
the next 48 hours. Therefore, continue to expect periods of heavy
rainfall and a high risk for flash flooding and mudslides across
the local islands.

&&

.SHORT TERM...Today through Thursday...

Very active weather conditions expected today and Wednesday. Very
deep tropical moisture associated with the tail of Tropical Storm
Eta, currently located over the southeastern Gulf of Mexico, will
remain over the area with precipitable water values expected to
range between 2.3 and 2.5 inches, which is near the 99th percentile
for this time of the year. In addition, a tropical wave located just
southeast of the area, will be entangled with this deep moisture
plume from Eta. As a result, the environment will be favorable for
organized enhanced rainfall activity to develop and affect the local
area. At this time, rainfall totals between 2 and 4 inches, with
isolated amounts of up to 6 inches, are expected each day for today
and Wednesday for eastern Puerto Rico and the USVI. Across western
Puerto Rico, the potential exists for rainfall amounts between 1 and
2 inches each day. The soils are saturated and streamflows along
rivers and streams, especially across eastern Puerto Rico, are
running above normal. Given that very significant rainfall activity
is expected, flooding and mudslides will be a major concern. As a
result, a Flash Flood Watch remains in effect through Wednesday
evening as the potential exists for any prolonged period of heavy
rainfall activity to create flash flooding, which in some cases may
be significant.

Weather conditions will gradually improve by Thursday as a drier air
mass will begin to move in. Moisture, however, will continue to be
sufficient to generate shower activity across eastern portions of
Puerto Rico and the USVI during the morning hours followed by the
development of afternoon convection across western Puerto Rico.
Rainfall accumulations for the most part on Thursday are expected to
be much less compared to what is expected today and Wednesday.

.LONG TERM...Friday through Wednesday...

A seasonal weather pattern is expected Friday and Saturday under
a much drier air mass. The precipitable water content is still
expected to range between 1.20 and 1.40 inches. However, this
available moisture is enough to combine with local effects and
diurnal heating to result in a few afternoon showers across the
interior and southwest Puerto Rico each day. Some passing showers
across portions of north and east PR as well as the USVI during
the overnight and early morning hours cannot be ruled out under an
east to east northeast wind flow.

The chance for organized convection is expected to increase early
next week as an upper low approaches the local islands from the
northeast. This feature will induce a surface trough, promoting
moisture advection late Sunday through at least midweek next week.
At this time, there is fair agreement between the GFS and ECMWF
guidance indicating the upper low east of the Lesser Antilles on
Sunday, crossing the forecast area on Monday with some weakening by
Tuesday. If model guidance is correct with its current solution,
unsettled weather conditions are expected once again late Sunday
through at least Wednesday with periods of showers and
thunderstorms.

&&

.AVIATION...SHRA activity will gradually increase through the
morning hours, becoming more widespread after 10/16z. Therefore,
VCSH is expected across all terminals through the period. MVFR to
possibly IFR conditions can be expected if SHRA activity moves
directly over the local terminals. Abundant cloud cover will cause
BKN ceilings between FL060-080, but will lower with any SHRA
activity. Winds will be light and variable through 10/12z,
increasing to 15 kts from the E-ESE after 09/14z, with some sea
breeze variations.

&&

.MARINE...Seas are building in response to increased winds across
the area as well as a small NE swell. Winds 20-25 knots to
continue for much of the week. Therefore, choppy to hazardous
conditions are likely to persist across the local waters and
passages. Small Craft Advisories are in effect for most of the
waters through at least Thursday. Periods of shower and isolated
thunderstorm activity can be expected across portions of the
regional waters today.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 84 75 84 75 / 80 80 80 70
STT 84 76 84 76 / 80 80 80 60

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
503 AM AST Thu Nov 12 2020

.SYNOPSIS...
A Flash Flood Watch continues for the islands as deep tropical
moisture linger over the area. A drier air pattern is anticipated
by the end of the week and for the weekend. However, moisture
returns to the area by next week, with more shower and
thunderstorms expected.

&&

.SHORT TERM...Today through Saturday...

Deep tropical moisture will linger today across the local area.
Numerous showers continue to be expected, which could cause
additional flooding, especially across eastern and southern PR.
Hence, the Flash Flood Watch continues in effect until 10 AM today.
There is also an upper trough that the forecast models position
north of the local islands with a tilted axis. This positioning is
good for thunderstorm development across the local area today,
especially when combined with diurnal heating, deep moisture and
surface convergence. This setup will promote the development of
additional showers and thunderstorms over the local islands and
waters, including western PR this afternoon.

Drier air starts moving in this evening and late tonight, promoting
a drying trend on Friday and the upcoming weekend. That said, the
upper trough will be in a less favorable location for
thunderstorms in the local area as it will be a bit further east.
But it could still promote isolated thunderstorms in areas of sea
breeze convergence such as western PR, and in streamers
off the Luquillo Mountain Range. That said, the available
moisture is expected to take a nosedive, with precipitable
water values near or just over one inch. Mostly fair weather
will be expected starting this Friday into the weekend, with brief
isolated to scattered showers in the forecast.

.LONG TERM...Sunday through Friday...
The drier weather pattern will extend into Sunday, with an upper
level high pressure near the Bahamas and an upper level trough to
the east-northeast of the forecast area. As a result, the islands
should remain in the subsidence side of these features. This will
result in limited rainfall activity for the area, with only a few
showers affecting eastern Puerto Rico and the U.S. Virgin Islands
early in the day, and afternoon showers over western Puerto Rico.
For the beginning of the workweek, both the ECMWF and the GFS are
showing that an upper level low will detach from the trough and
retrograde into the islands. By Tuesday, The GFS keeps the low
east of the Lesser Antilles, and the ECMWF has the feature closer.
Nevertheless, mid-level temperatures are expected to cool down in
response, which should increase the risk for thunderstorm
activity over the area. Additionally, a surface-induced trough is
expected to develop, causing an increase in moisture through mid-
week.

Moving into the end of the workweek, a frontal system will
approach to the eastern Caribbean, but so far, the guidance is
keeping the front stalling to the north of the area. However, an
easterly disturbance is expected to approach from the southeast.
This will supply additional moisture, with precipitable water
forecast to rise to 1.8 to 2.0 inches in the period. Therefore,
showers and isolated thunderstorm activity is anticipated to
continue through the end of the long-term forecast period.

&&

.AVIATION...SHRA and ISOL TSRA expected across the local flying
area, causing VCSH, but VCTS is possible after 12/14Z. CIGs will be
near FL060-080 across the flying area, lower near SHRA/TSRA. Winds
will be from the east at 10-20 kt with occasional gusts and sea
breeze variations.


&&

.MARINE...
Choppy and hazardous marine conditions continue to moderate to
fresh winds over the area. Therefore, small craft advisories are
in effect due to seas up to 8 feet. and winds up to 20 knots.
Shower activity will continue over the waters, especially through
the early part of the day. For the beaches, a high rip current
risk continues for the northern coast of Puerto Rico and eastern
St. Croix.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 85 75 87 76 / 50 20 20 20
STT 85 75 86 76 / 50 20 20 20

&&

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
411 AM AST Fri Nov 13 2020

.SYNOPSIS...
A drier air pattern is expected to the islands through the
weekend. Moisture returns for early into the middle of the next
workweek, and with it, showers will increase once again across the
region. Hazardous seas will continue across the Atlantic waters
today, with choppy seas expected through Sunday.

&&

.SHORT TERM....SHORT TERM...Today through Sunday...

With the exception of a little patch of moisture across the
Caribbean waters, causing showers south of PR this morning, mainly
fair weather is expected today and through this weekend, as drier
air starts to move in from the north. An upper-level low to the
northeast of the local islands will remain to our north and east for
the next few days, keeping the local islands in the subsident side.
Therefore we expect mainly stable conditions. That said, there is
the possibility of isolated to scattered showers, especially across
western PR where moderate showers are possible in the afternoons,
though not expected to be too long lasting or to cause more than
perhaps some ponding of water in poor drainage areas. Elsewhere,
mainly brief isolated showers, if any, are expected.

Like it was mentioned above, drier air is moving in. Satellite
derived precipitable water indicates that precipitable water just
north of the local islands is about 1.1 to 1.3 inches, and it is
moving south towards the local islands. The latest model guidance
suggests that the precipitable water will drop to about 1.2 to 1.3
inches today, possibly dropping a bit more on Saturday to around 1.1
inches , then bouncing back to around 1.3 inches on Sunday. To put
things into perspective, 1.1 to 1.3 inches is below the 25th
percentile compared to climatology for this time of year. The
forecast soundings indicate that the mid levels will be very dry,
and even if local effects cause some shower development across
western PR or stream off the mountains, the shower activity would
likely be shallow. But, given the the overall picture and guidance,
mainly fair weather would be expected from today until Sunday, with
Saturday being the driest day.

As far as winds and temperatures, we expect somewhat breezy
conditions from the east today, while winds will decrease slightly
on Saturday and Sunday. A slight shift to NE winds is forecast on
Sunday, as a SFC high pressure enters the western Atlantic.
Temperatures will be seasonable, with daytime highs in the mid to
upper 80s across the lower elevations and in the upper 70s to low
80s across the higher elevations. The overnight low temperatures
would be around the mid 70s across the lower elevations, and in the
mid 60s to low 70s across the higher elevations.

.LONG TERM...Monday through Saturday...
The main feature for the beginning of the workweek will be an
mid to upper level low pressure to the east of the islands that is
expected to move closer to the forecast area. This will induce a
surface trough northeast of the Caribbean. For Monday, the air
mass is expected to remain dry enough to prevent significant
rainfall accumulation. However, groups of clouds associated with
the surface trough will begin to advect some showers over eastern
Puerto Rico and the U.S. Virgin islands, and then, in the
afternoon, convection over western Puerto Rico due to local
effects.

By late Monday into Tuesday,the surface trough will get closer to
the area, increasing low level moisture content. Also, as the mid
to upper level low approaches, mid level temperatures will cool
down, hence increasing instability aloft. Therefore, the risk for
thunderstorm development will increase as well. Additionally,
later on Tuesday into Wednesday, a tropical wave will also reach
the islands, further increasing the potential for showers across
the area. However, the upper level low is forecast to weaken by
mid-week, decreasing support aloft for strong shower development.
Moisture associated with the tropical wave should linger through
the rest of the week, with the potential for showers for each day.


&&

.AVIATION...Fair weather is expected across the local terminals
through the forecast period. Winds at around 15 knots with
occasional gusts are expected today, decreasing after 13/22Z. VCSH
is possible at TJBQ between 13/18Z and 13/21Z, while any other VCSH
elsewhere would be brief in ISOL SHRA.


&&

.MARINE...
Choppy and hazardous seas continue today across the Atlantic
waters and passages, with seas up to 7 feet. Small craft
advisories remain in effect. Seas are expected to subside today,
but will remain choppy, up to 6 feet with winds up to 20 knots
expected through the weekend. For the beaches, there is a high
rip current risk for the northern coast of Puerto Rico and eastern
St. Croix.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 87 76 86 77 / 20 20 20 20
STT 86 76 86 76 / 20 20 20 20

[cycloneye]

AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
503 AM AST Sat Nov 14 2020

.SYNOPSIS...Below normal moisture and an upper level low to the
northeast of the local islands will maintain subsidence and
generally stable conditions this weekend. Moisture will increase
slightly on Monday, but a tropical wave will bring deeper moisture
on Tuesday, with the deep moisture lingering for most of the
workweek as a surface high enters the western Atlantic, causing an
old frontal boundary to stall north of the local islands.

&&

.SHORT TERM...Today through Monday...

A surface high pressure over the western Atlantic and a surface
trough to the east of the islands will continue to promote an east-
northeasterly wind flow through the rest of the weekend. A mid-to-
upper level low pressure system is located to the east of the Lesser
Antilles. Puerto Rico and the U.S. Virgin Islands are currently
located under the subsidence side of the trough, so mainly tranquil
weather is anticipated for today. Satellite-derived precipitable
water values show a relatively dry air mass enveloping the islands.
However, infrared satellite imagery and Doppler radar indicate some
showers moving around the northeast coast of Puerto Rico and the
U.S. Virgin Islands. Then, in the afternoon, diurnal heating should
aid in the development of some showers over southwestern Puerto
Rico. Due to the lack of upper level support, significant rainfall
accumulation is not anticipated.

As the short-term forecast period progresses, moisture associated
with the surface trough will begin to reach the area. On Sunday, the
GFS now shows precipitable water values around 1.5 inches. This will
support additional showers developing in the afternoon over western
Puerto Rico. For Monday, the mid level trough migrates southeast of
the islands. As a result, the trade wind inversion will weaken,
resulting in an increase in shower activity. This will, once again,
fuel afternoon convection across western Puerto Rico, with
additional showers advection occurring over eastern PR/USVI through
the morning and overnight hours.

.LONG TERM...Tuesday through Sunday...

A rainy pattern appears to make a return for most of next week, as
a tropical wave approaches the local area on Tuesday into
Wednesday, causing a significant increase in available moisture.
There is also a SFC low pressure across the western Atlantic that
moves north and makes way for a surface high pressure to enter the
western Atlantic, which then causes the frontal boundary to stay
to our north and keep the local islands under the deep moisture
for the rest of the long term period. Even though we are in the
long term forecast, and confidence is generally low, the long
term guidance has been consistently showing this pattern for a few
days now, and it has been suggesting an increase in shower
activity from Tuesday and for the rest of the workweek, with
Wednesday into Thursday being the rainiest period, probably
because the upper levels would have a broad trough to our
northwest, causing a SFC induced trough and increasing the
chances of thunderstorms in the local area. That said, the GFS
model indicates that the moisture lingers into the weekend, but
the rainfall amounts decreases as instability also decreases.

&&

.AVIATION...VFR conditions are expected to prevail through the
forecast period. VCSH are possible at TJPS after 14/17Z, which could
briefly reduce visibility to MVFR conditions. Fair weather is
anticipated for the rest of the terminals. Winds will be out of the
east at 10 to 15 knots.


&&

.MARINE...Small craft should exercise caution as moderate to
locally fresh winds cause choppy seas up to 6 feet across most of
the local waters today. However, choppy seas may be observed
tonight and early Sunday as well. Winds will be mainly from the
east to ENE up to 20 knots today, decreasing to 15 knots by
tonight. There is a high risk of rip currents for the beaches of
northern Puerto Rico and eastern Saint Croix, with a low or
moderate risk elsewhere.



&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 85 77 85 75 / 20 30 40 30
STT 86 76 86 76 / 20 20 50 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
443 AM AST Sun Nov 15 2020

.SYNOPSIS...The local islands will be in the subsident side of an
upper low to the east northeast today and early Monday, but a
broad trough starts approaching the local islands from the
northwest by midweek. A tropical wave is expected late on Tuesday
into Wednesday, and available moisture will increase through from
that point through the end of the week. Relatively benign weather
is expected today, with only isolated to scattered brief showers,
as northeast winds with drier than normal available moisture is
expected.

&&

.SHORT TERM...Today through Tuesday...

The islands will remain under the envelop of a drier air mass
through the day. However, the latest imagery from Total Precipitable
Water shows a pocket of slightly higher values north of the area,
resulting in some passing showers that may move over northern and
eastern Puerto Rico and the U.S. Virgin Islands early in the day.
The main feature over the area is a mid to upper level low pressure
just to the east of the Lesser Antilles. Since the forecast area
remains in the subsident side of this system, conditions are
expected to remain unfavorable for strong convection to develop.
In the afternoon however, local effects should combine with low
level moisture to generate showers over southwestern Puerto Rico.

For tomorrow, the local guidance indicate that the mid-level low
will move closer to the regional area, which should weaken the trade-
wind inversion. Additionally, a little bit more moisture is expected
to filter in. As a result, morning showers will continue to be
advected over eastern PR/USVI early in the day, followed by more
showers over the interior and western Puerto Rico. For Tuesday, a
tropical wave will also provide approach the local islands. Also,
both the GFS and ECMWF models are indicating mid-level temperatures
cooling down to around -6 degree Celsius. Due to this increase in
instability, there will be the potential for some afternoon
thunderstorms developing over western Puerto Rico. Some ponding of
water on low-lying and poor drainage areas will be possible with
this activity.

.LONG TERM...Wednesday through Monday...

The latest guidance has backed off compared to yesterday, and now
indicates less amount of rain, but still a similar pattern to
what it was previously forecast. That said, a rainy or perhaps
unsettled pattern is forecast this upcoming workweek, especially
starting late Tuesday into Wednesday and onward, as a tropical
wave approaches the local area, causing a significant increase in
available moisture. In addition to the tropical wave, the latest
model guidance still indicates that a SFC low pressure across the
western Atlantic will move north and make way for a surface high
pressure to enter the western Atlantic, which then causes the
frontal boundary to stall to our north and keep the local islands
under the deep moisture through at least Saturday, with some faint
indication of drier air moving in on Sunday and Monday. It appears
now that Wednesday and then Friday would be the rainiest days in
the long term forecast, with Friday being the rainiest as a
shortwave trough moves through. This sort of inconsistency in the
model increases uncertainty and one must also consider that the
model develops yet another tropical system in the southwestern
Caribbean, which may have an impact in the model solution for the
local area depending on its intensity and track.

&&

.AVIATION...VFR conds expected across all terminals through the
forecast period. VCSH could develop after 15/17Z across TJPS,
which could result in brief MVFR conditions due to reduced
visibility and lower ceilings. Winds will be out of the northeast
at 10 to 15 knots.eriod. VCSH could develop after 15/17Z across
TJPS, which could result in brief MVFR conditions due to reduced
visibility and lower ceilings. Winds will be out of the northeast
at 10 to 15 knots.


&&

.MARINE...East to NE winds up to 15 knots today will cause choppy
seas up to 6 feet across the local waters. Therefore small craft
operators are urged to exercise caution. These moderate winds will
continue for the next few days, causing seas to be generally
between 3 and 6 feet. There is a moderate or low risk of rip
currents across the local beaches for the next several days.
A northerly swell is possible late this week, which may cause
seas to become hazardous.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 86 75 87 76 / 40 30 30 30
STT 87 75 86 76 / 30 30 50 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
431 AM AST Mon Nov 16 2020

.SYNOPSIS...
Passing showers could reach eastern sections of Puerto Rico and
the U.S. Virgin Islands in the morning hours. However, mostly
clear to partly cloud skies are forecast for the rest of the
area. In the afternoon hours, afternoon convection with shower
activity is expected over western and interior sections of Puerto
Rico. Across the regional waters, easterly wind flow will result
in choppy marine conditions with seas up to 6 feet and winds up to
15 knots. Therefore, small craft operators should exercise
caution over the Atlantic offshore waters.


&&

.SHORT TERM...Today through Wednesday...

Tutt Low and associated deep layered trough east of the northern
Leeward islands is forecast to sink southwards across the Lesser
Antilles while gradually filling through Wednesday. Meanwhile the
upper level ridge in place across the region is forecast to
gradually weaken but will maintain the area on the subsidence and
stable side of the upper trough at least until Wednesday. A surface
high pressure ridge across the west central Atlantic and the deep
layered high amplitude trough east of the region will maintain a
moderate northeast wind flow across the region today. Winds will
become more east to southeast by Tuesday and Wednesday as as a low
level trough and accompanying surge of moisture is forecast to cross
the region ahead of a tropical wave also forecast to approach the
Lesser Antilles late Wednesday.

During the rest of the early morning hours today, patches of low
level clouds with embedded showers will be transported in across the
region in the dominant northeasterly wind flow. These showers will
continue to reach portions of the north and east coastal areas of
the islands from time to time bringing periods of moderate to
locally heavy rains in isolated areas. However, significant rainfall
accumulations are not expected as the shower activity will be fast
moving and of short duration.

For the afternoon hours lingering moisture along with local sea
breeze convergence will favor shower development over parts of the
central interior and southwest sections of Puerto Rico as well as on
the west-end or just downwind of the U.S. Virgin islands. Some late
afternoon showers may also affect parts of the San Juan metro but
the activity will also be of short duration.

Later today into Tuesday, recent model guidance continued to suggest
a gradual shift in the low level wind flow as it becomes more east
southeast. This is in response to the induced low level trough and
surge of moisture forecast to approach the region by Tuesday. This
will result in better potential for shower development, as well as
an environment more conducive for the development of isolated
thunderstorms across the forecast area, especially during afternoon
due to daytime heating and local effects. By then, expect scattered
to numerous showers to be focused mainly over portions of the
interior and northwestern portions of Puerto Rico as the steering
flow becomes more east-southeast. Minor urban and small stream
flooding as well as ponding of waters on roadways and in poor
drainage areas will be possible in isolated areas with the heaviest
rains.

On Wednesday, model guidance suggest continued to suggest increase
in moisture transport with precipitable water ranging between 1.70
to 2.0 inches across the forecast area. This along with the
amplifying upper trough and cooler 500 millibar temperatures east of
the region should enhance shower development and consequently induce
isolated thunderstorm development over the coastal waters between
eastern Puerto rico and the U.S. Virgin Islands during the overnight
an. d early morning hours. That said, expect increased potential for
afternoon shower development with scattered to numerous showers and
isolated thunderstorms for Wednesday as well over the islands. For
now, the best chance for minor urban and small stream flooding
should be over the central interior and northwest sections of Puerto
Rico as well as parts of the San juan metro area during the
afternoon hours.

.LONG TERM...Thursday through Tuesday

A unsettled weather pattern is expected for the long term period
forecast. Once again, the latest model guidance continues to show
a surface low pressure over the western Atlantic, which causes a
frontal boundary keep in place just of our north and maintain the
forecast area under tropical moisture at least until Sunday. In
the upper levels, a upper level trough will continue to sink into
the south and will result in a induce surface trough between late
Thursday into Friday. Also, GFS model guidance suggest cooler
temperatures at 500 mb ranging between -6 to -7 C on Thursday and
Friday increasing the potential for thunderstorms activity. That
said, a active weather pattern is forecast between Thursday to
Saturday with more widespread activity. The main focus for the
shower activity will be the interior and western sections of
Puerto Rico as a easterly northeasterly wind flow domain the
region. In the morning hours, isolated to scattered showers could
reach eastern Puerto Rico ans the U.S. Virgin Islands from time to
time.

On Sunday, a more southeasterly wind flow is expected over the
area. The combination of the lingering moisture and the local
effects will produce scattered showers over the northwestern
quadrant in the afternoon hours. A more stable weather pattern is
expected on Monday and Tuesday, as a drier airmass filters into
the region limiting the showers activity.


&&

.AVIATION...VFR conds will prevail at all TAF sites durg prd. VCSH
are expected at most terminals with SCT SHRA psbl at TJSJ/TISX/TIST
til 16/14Z and fm 16/18Z-16/22Z. Sfc winds lgt/vrb bcmg fm E at 10-
15 KT with sea breeze variation and psbl gusts to 20-25 KT aft
16/14Z. L/lvl wnd fm E-NE 15-20 kts BLO FL150 then backing and incr
w/ht ABV.



&&

.MARINE...
Moderate northeasterly to easterly wind flow will continue to result
in choppy marine conditions over Atlantic offshore with seas up to 6
feet. Therefore small craft operators should exercise caution over
the local waters. There is a moderate risk of rip currents for
northern beaches of Puerto Rico for today. Elsewhere, a low risk of
rip current is expected. For the end of the workweek, a northerly
swell is expected to reach the region and may result in hazardous
marine conditions over the area. An increase in shower activity and
coverage is expected on Tuesday to Wednesday as a Tropical wave
move into the region.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 86 76 86 76 / 50 30 30 20
STT 86 77 85 74 / 40 50 50 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
456 AM AST Tue Nov 17 2020

.SYNOPSIS...
An increase in shower and thunderstorms activity is
forecast for today. Passing showers are expected to continue to
move from the waters to eastern and northern sections of the local
islands in the morning hours. Then, in the afternoon hours
afternoon convection is expected over northwestern Puerto Rico.
Ponding of waters over roadways could not be ruled out with the
heaviest showers. Tranquil marine conditions will prevail for
today with seas between 3 to 5 feet and winds up to 15 knots.


&&

.SHORT TERM...Today through Thursday
Tutt Low and associated deep layered trough east of the region
will continue to sink southwards across the Lesser Antilles while
gradually filling over the next few days. The upper level ridge
has shifted slightly west of the region but will maintain a
northerly wind flow aloft while keeping the forecast area on the
subsident and stable side the aforementioned upper trough. A
surface high pressure ridge has shifted eastward into the north
central Atlantic while a broad induced deep layered trough
continues across the northeastern Caribbean. This pattern will
maintain an east southeast low level wind flow across the region
through the period. An easterly disturbance will continue to cross
the region today accompanying a surge of low level moisture. This
will be followed by a weak tropical wave also forecast to move
across the region Wednesday into Thursday.

For the rest of the early morning hours, patches of low level clouds
with embedded showers will continue to affect the coastal waters
while brushing parts of the islands from time to time. Some showers
will produce periods of moderate to locally heavy rains that may
cause ponding of water on roadways and in poor drainage areas as well
as brief hazardous driving conditions. Significant rainfall
accumulations are however not expected as the shower activity will be
fast moving.

Skies will become mostly sunny to partly cloudy the rest of today.
However, the available pooling of low level moisture along with
daytime heating and local effects will give way to afternoon shower
development and possibly isolated thunderstorms mainly over parts of
the central interior and west section of Puerto Rico. Shower
activity over the U.S. Virgin Islands should be limited to mainly
portions of the west end of the islands or just downwind over the
coastal waters. Some afternoon showers may again affect parts of the
San Juan metro but the activity will also be of short duration.
Minor urban and small stream flooding as well as ponding of waters
on roadways and in poor drainage areas will be possible in isolated
areas with the heaviest rains mainly over the west sections of
Puerto Rico.

Recent model guidance initialized will and is in phase with the
present and expected weather pattern. A prevailing east southeast
wind flow is forecast to persist through the period with model
guidance suggesting increasing layered precipitable water to between
1.70 to 2.0 inches today through Thursday. This along with the
amplified upper trough and cooler 500 millibar temperatures east of
the region should enhance shower development and consequently induce
isolated thunderstorm development over the coastal waters between
eastern Puerto rico and the U.S. Virgin Islands during the overnight
and early morning hours. Therefore, still expect good potential for
early morning showers and daytime convection for the rest of the
period. That said, the potential for minor urban and small stream
flooding as well as ponding of waters on roadways and in poor
drainage areas will remain possible each day in isolated areas with
the heaviest rains. Near seasonal temperatures should persist across
the region through Thursday.

.LONG TERM... Friday through Wednesday

At the surface, abundant tropical moisture from the last tropical
wave are forecast to linger over the region as a surface low
pressure build over the western Atlantic. According to the GFS
model guidance plenty of moisture will prevail at 850 mb
increasing the potential for more widespread shower activity for
the weekend. In the upper levels, a building upper level trough
(TUTT) will sink into the south inducing a surface trough at our
north. Generally speaking, a unsettle weather pattern is expected
on Friday until through at least Sunday. Therefore, urban and
minor flooding is expected in the areas with the heaviest showers.
In terms of temperatures, a more warmer daytime temperatures are
expected on Sunday as a more southeasterly wind flow dominate the
region.

On Tuesday, the TUTT will be in a better position for the
instability aloft over the area. This will enhance the potential
for shower and thunderstorms activity over the areas. Especially
on Tuesday when a more cooler temperatures are forecast at 500 mb
around -8 Celsius. The limiting factor for a more widespread
showers will be the lack of moisture over the area. As a building high
pressure move over the area with a more somewhat drier air filter
into the region on late Tuesday into Wednesday. That said, less
showers activity with mostly partly cloudy skies were prevail for
the last day of the long term period.

&&

.AVIATION...
VFR conds will prevail durg prd. VCSH at most terminals
with SHRA psbl at TJSJ/TISX/TIST/TNCM and VCTS at TKPK til 17/14Z.
SCT-BKN lyrs nr FL025...FL050 en route btw islands and ovr coastal
waters. Fm 17/17Z-17/22Z VCSH/Isold TSRA psbl at TJBQ/TJMZ/TJSJ. Sfc
wnds lgt/vrb bcmg fm E at 10-15 KT with sea breeze variation and hir
gusts btw 20-25 KT aft 17/14Z. L/lvl wnd fm ESE 15-25 kts BLO FL200
then backing and incr w/ht ABV.

&&

.MARINE...
Relative tranquil marine conditions are expected for today with moderate
easterly winds across the regional waters. Seas are expected to
be generally between 3 and 5 feet over all the regional waters. A
increase in shower and thunderstorms activity is expected this
afternoon as a tropical wave move across the northeastern
Caribbean. Seas will become hazardous on Friday when a northeast
swell enters the area.




&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 86 76 87 77 / 50 40 50 20
STT 85 76 85 75 / 50 60 50 40