Caribbean - Central America Weather

[cycloneye]

AFDSJU

Area Forecast Discussion...CORRECTED
National Weather Service San Juan PR
505 AM AST Thu Aug 25 2022

.SYNOPSIS...

A trade wind perturbation will bring showery weather across the
U.S. Virgin Islands, eastern, north, and southeast Puerto Rico
through the morning. Afternoon convection will develop across the
Cordillera Central and west Puerto Rico, increasing the potential
for urban and small stream flooding. The San Juan Streamer could
promote urban flooding across the metropolitan area too. A
tropical wave will cross the Lesser Antilles tonight, leaving its
bulk of moisture south of the islands over the Caribbean Sea. The
National Hurricane Center actively monitors this disturbance;
additional information is available in the Tropical Weather
Outlook (TWOAT) or www.nhc.noaa.gov. An unstable weather pattern
is possible for early next week.

&&

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

A trade wind perturbation will continue to bring humidity and
scattered showers throughout the morning hours mainly over eastern
Puerto Rico, Vieques, Culebra and the USVI. Humid air that will
reach the area will reach precipitable water values of around 2
inches, above normal values for this time of the year. Due to
unfavorable conditions for development, such as drier air in the
upper levels and upper- to mid- level ridging, the shower activity
affecting our area will not have much development. During the
afternoon hours, more activity is expected as the humidity in the
area along with local and diurnal effects will result in shower
activity and thunderstorms over the interior and western Puerto
Rico along with possible streamers from El Yunque affecting the
San Juan metro area. Continuous showers can result in ponding of
water and possibly urban and small stream flooding. Moisture along
with maximum temperatures from the upper 80s to the low 90s will
result in heat index values in the low 100 degrees, especially
along coastal and urban areas.

A tropical wave is expected to reach the Lesser Antilles by late
tonight or early tomorrow. This disturbance is currently being
monitored by the NHC, who gave it a low formation chance of near 0
percent through the next 48 hours and 20 percent through the next
five days. This low formation chance of 20 percent through the next
five days could occur in the Caribbean Sea, where most of the shower
and thunderstorm activity related to it is expected to remain.
Additional information about this system can be found in the NHC`s
Tropical Weather Outlook (TWOAT) product or in www.nhc.noaa.gov.
Nevertheless, general increase in moisture will maintain and
slightly increase the typical weather pattern of showers over
eastern Puerto Rico and the USVI in the morning and deep shower
activity over western Puerto Rico in the afternoon. This pattern
will continue albeit with slightly more humidity to start the
weekend with most of the activity related to the disturbance staying
in the offshore Caribbean waters, with precipitable water values
near 2 inches. Late Saturday, a wind surge along with a band of
moist air is also forecast to reach the region, increasing rain
chances.

&&

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

GFS is now backing-up about the amount of rain possible for
Sunday, having just a wind surge with a band of moisture brushing
the islands. However, the typical weather pattern looks more
likely now. A tropical wave is forecast to reach the Northeast
Caribbean late Sunday night into Monday, increasing showers and
thunderstorms. Monday and Tuesday present the best chance of
unsettled weather conditions in the Long Term Forecast. ECMWF and
GFS indicated plenty of tropical moisture lifted from the south
over Puerto Rico and the U.S. Virgin Islands. If model guidance is
correct, the potential for urban and small stream flooding,
numerous showers, and scattered thunderstorms may affect the
region.

A dry air mass with suspended African Dust particulate should
reduce rain activity and create hazy skies Wednesday and possibly
Thursday. Although we cannot rule out the advection of showers
during the morning and nighttime and afternoon convection due to
local and diurnal effects, this activity could be limited,
especially on Wednesday. A set of trade wind perturbations will
bring additional moisture to promote better afternoon convection
Thursday and Friday.

In addition, Puerto Rico and the U.S. Virgin Islands residents can
expect the warming trend to continue with heat index values
surpassing 100s degrees Fahrenheit each afternoon, especially
Wednesday through Friday.

&&

.AVIATION...

(06Z TAFS)

Generally VFR conditions will prevail today.
Btwn 25/17-22z, SHRA/TSRA will form across the interior and western
Puerto Rico and a San Juan streamer could affect the metro area.
Most of the activity is expected in the VCTY of the local terminals.
Winds should increase to 15-20kt at around 25/16z, with sea breeze
variations and higher gusts.

&&

.MARINE...

Generally moderate easterly winds are expected to prevail due to
a surface high pressure system over the Atlantic. Showers will
continue to affect the local waters and thunderstorms will
develop, mainly during afternoon. Small craft should exercise
caution in the local Atlantic waters and near thunderstorms due to
locally fresh winds and higher seas.

There is also a moderate risk of rip currents for the north-
facing beaches of Puerto Rico from Aguadilla to Loiza, with a low
risk of rip currents elsewhere.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...None.
VI...None.
&&

$$

SHORT TERM...MRR
LONG TERM....CAM
AVIATION...MRR

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
514 AM AST Fri Aug 26 2022

.SYNOPSIS...

A tropical wave is moving westward across the eastern Caribbean
Sea, with its bulk of moisture off to the south of the Virgin
Islands and Puerto Rico today and tomorrow. Once again, afternoon
convection across the Cordillera Central and west Puerto Rico and
near the San Juan Metropolitan area will increase the potential
for urban and small stream flooding. The Virgin Islands can expect
most of the shower and thunderstorm activity across its
surrounding waters. An unstable weather pattern is likely for
early next week.


&&

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

Expect a generally typical weather pattern for today, albeit
somewhat drier, especially in the mid levels, than the past few
days. Passing showers should continue to affect our local waters
and the eastern forecast area mainly during the morning hours.
During the afternoon hours, more activity is expected as local and
diurnal effects will result in shower activity over the interior
and western Puerto Rico along with streamers from El Yunque
affecting the San Juan metro area and vicinity. These showers can
result in ponding of waters on roadways. Winds will generally be
from the east at around 15 knots and maximum temperatures should
reach the upper 80s to the low 90s with heat index values in the
low 100 degrees, especially along coastal and urban areas.
Moisture related to a tropical wave reaching the Caribbean Sea
will continue to filter into our local waters during the morning
hours and current model guidance shows that this moisture with
precipitable water values at or slightly below 2 inches will cover
our southern coastal waters by late tonight and early tomorrow.
This disturbance is currently being monitored by the NHC, who gave
it a low formation chance of near 0 percent through the next 48
hours and 20 percent through the next five days. Most of the
shower and thunderstorm activity related to it is expected to
remain south of our forecast region in the Caribbean Sea.
Additional information about this system can be found in the NHC`s
Tropical Weather Outlook (TWOAT) product or in www.nhc.noaa.gov.

On late Friday and heading into Saturday morning, the increased
moisture related to the tropical wave south of our region will
enhance shower activity, and will aid in the typical weather pattern
in generally the same areas as on Friday with the exception of
enhanced shower and thunderstorm activity over the Caribbean waters
due to the moisture related to the tropical wave. Current model
guidance has back off on any moisture reaching the region on
Saturday night so a drying trend will be observed during that night
as moisture related to the tropical waves moves out of our southern
waters by late Saturday and early Sunday. This leaves Sunday, as the
relatively driest day of the weekend and with the typical weather
pattern again in similar areas, current model guidance shows that
moisture related to another tropical wave will start to reach the
easternmost waters as we head into the long term period.

&&

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

A tropical wave is forecast to reach the U.S. Virgin Islands and
Puerto Rico late Sunday night and Monday, creating favorable
weather conditions for the development of widespread showers and
scattered thunderstorms. The trailing moisture will stay over the
islands until Tuesday afternoon when a drier air mass with
suspended African dust particles is forecast to arrive. This air
mass will reduce the potential for widespread activity. However, a
TUTT low lingering over the Northeast Caribbean combined with
excessive heating, local effects, and sea breeze variations may
result in isolated afternoon strong thunderstorms.

Model guidance suggests the TUTT-low amplifying over the islands
on Thursday and Friday. Induced surface perturbations will affect
the islands as this feature retrograde across the region,
promoting unstable weather conditions. If model guidance is
correct, the potential for urban and small stream flooding,
numerous showers, and scattered thunderstorms may affect the
region.

A tropical wave, now located near the Cabo Verde Islands over the
Eastern Atlantic Ocean, and actively monitored by the National
Hurricane Center, is forecast to approach the region by the end of
the workweek into the weekend. Although ECMWF and GFS have some
discrepancies with the time of the arrival and the intensity of a
tropical cyclone, both guidances are now suggesting a tropical
cyclone near the region by the weekend. As we approach the month
of September, we encourage residents, tourists, and visitors in
Puerto Rico and the U.S. Virgin Islands to review their emergency
plans and actively monitor the products issued by your Weather
Forecast Office and the National Hurricane Center.

In addition, model guidance suggests a warming trend with heat
index values surpassing 100s degrees Fahrenheit each afternoon,
especially Wednesday through Friday.

&&

.AVIATION...
(06Z TAFS)

VFR conditions will prevail today. Btwn 25/17-22z, similar to
yesterday SHRA/ ISOLD TSRA affecting interior and western Puerto
Rico and a San Juan streamer could affect the metro area. Most of
the activity is expected in the VCTY of the local terminals. Winds
should increase to 15-20kt at around 25/15z, with sea breeze
variations and higher gusts.

&&

.MARINE...

Light to moderate easterly winds will prevail across the regional
waters due to a surface high pressure across the Atlantic Ocean.
A tropical wave will move westward across the eastern Caribbean
throughout the day. Isolated thunderstorms are possible across
the Caribbean waters with the wave passage. A small swell will
move across the local waters today.

A moderate risk of rip currents will continue across the northern
beaches of Puerto Rico and in Cramer Park St Croix, and a low
risk elsewhere across the islands.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...None.
VI...None.
&&

$$

SHORT TERM...MRR
LONG TERM....CAM
AVIATION...CAM

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
507 AM AST Sat Aug 27 2022

.SYNOPSIS...
Lingering moisture will promote showers and a few thunderstorms
over the local waters during the morning hours. Morning showers
should will also affect the USVI and eastern PR. More significant
shower and thunderstorm activity is expected across central to
west northwestern PR, and possibly the San Juan metro area, during
the afternoon. Rains during the last few days in those same areas
increase the possibility of urban and small stream flooding with
significant showers. Heat index values could reach up to 107
degrees over coastal areas of Puerto Rico. On Monday, another
tropical wave is expected to cause an increase in moisture and
shower activity.

&&

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

Moisture associated with a tropical wave will linger through the
morning hours. Showers and a few thunderstorms will affect the
local waters in the morning, but it is expected to gradually
improve as the day progresses. Shower activity is also expected to
affect the USVI at times and eastern PR in the morning, but more
significant shower and thunderstorm activity is expected across
central to west northwestern PR in the afternoon. There is also a
possibility of shower and thunderstorms across portions of the San
Juan Metro this afternoon. Given the recent rain across the
aforementioned areas, urban and small stream flooding would be a
possibility with these more significant showers.

By Sunday, precipitable water values will be near normal, and a
rather typical pattern is expected, with isolated to scattered
showers in the morning and nighttime hours over the waters, USVI,
and eastern PR, followed by thunderstorms across western PR in the
afternoon. Some lines of showers streaming off the outlying
islands, as well as streaming off the Luquillo Mountain Range,
would affect portions of PR on Sunday afternoon, which would
include the San Juan Metro.

A tropical wave is expected to move in on Monday, causing an
increase in moisture and also in shower activity. Therefore widely
scattered to locally numerous showers are forecast at different
times through the local islands.

&&

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

The long term forecast period will start off with most of the
moisture related to the tropical wave exiting our region and making
way for a drier air mass, with around normal precipitable water
values, along with a Saharan Air Layer (SAL). This can limit
shower activity. However, the typical weather pattern should
remain, with passing showers mainly over the eastern forecast area
and shower activity with isolated thunderstorms, during the
afternoon hours over the interior and western municipalities of
Puerto Rico due to diurnal heating and local effects. In the upper
levels a TUTT will position itself over our forecast area on
Thursday and Friday. This, along with patches of moisture entering
the region, can serve to enhance the typical weather pattern and
create an increased risk of thunderstorms and urban and small
stream flooding.

By late Friday and into the weekend, current model guidance shows
moisture associated with a tropical wave affecting our region. The
National Hurricane Center (NHC) is monitoring this tropical wave as
it is currently producing disorganized showers and thunderstorms in
the eastern tropical Atlantic. This system currently has a low
formation chance, with a 10 percent chance through 48 hours and a 30
percent chance through 5 days. Additional information about this
system can be found in the NHC`s Tropical Weather Outlook (TWOAT)
product or in www.nhc.noaa.gov. Weather conditions in the region
will be tied to the development of this system, but it still has the
potential to bring heavy rainfall. The GFS currently has an open
wave affecting us while the ECMWF has tropical cyclone. Both the GFS
and the ECMWF also have discrepancies with regards to timing and
intensity and it is still to early to determine exact impacts, if
any. We will continue to monitor the future development of this
system throughout the coming days. Nevertheless, as we enter the
month of September, peak hurricane season, we encourage everyone
to review their emergency plans.

&&

.AVIATION...VFR conds are expected across the local terminals for
most of the day. VCSH expected across the local terminals in the
morning, with TJPS observing TEMPO SHRA through 27/10Z. VCTS is
forecast for TJSJ and TJBQ after 27/17Z, but TJBQ may observe MVFR
conds as TSRA may affect the terminal. Winds will be from the
east at around 10-15KT with occasional gusts and sea breeze
variations.

&&

.MARINE...Light to moderate easterly winds will prevail across
the regional waters during the next few days with seas of up to 5
feet. Locally fresh winds of up to 20 knots are possible over the
coastal Atlantic Waters. Lingering moisture over the Caribbean
waters will promote showers and isolated thunderstorms through
this morning. There is a moderate risk of rip currents across the
north, east, and southeast facing beaches of Puerto Rico. There is
a low risk elsewhere.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...None.
VI...None.
&&

$$

SHORT TERM...JA
LONG TERM....MRR
AVIATION...JA

[cycloneye]

National Weather Service San Juan PR
508 AM AST Sun Aug 28 2022


.SYNOPSIS...

Typical weather conditions are expected for today, with heat
indices up to around 105 in coastal areas. Afternoon convection is
expected to affect western and interior portions of Puerto Rico
today. A tropical wave is forecast to bring an increase in shower
and thunderstorm activity to the region tomorrow, followed by
drying for midweek. There is high uncertainty for the forecast for
next weekend, associated with the passage of a low to the
northeast.

&&

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

For today, precipitable water values will be near normal, and a
fairly typical pattern is expected, with scattered showers in the
morning over the waters, USVI, and eastern PR, followed by
thunderstorms across western PR in the afternoon. However,
Scattered showers and isolated thunderstorms are forecast across
eastern Puerto Rico this afternoon as well, which includes the San
Juan Metro. Given the recent rainfall across several sectors of
Puerto Rico, isolated areas may observe urban and small stream
flooding this afternoon. Temps will be in the upper 80s to low 90s
across the lower elevations, with heat index generally between 98
and 105. The higher elevations may observe high temps in the low
to mid 80s.

A tropical wave is expected to move in on Monday, causing an
increase in moisture and also in shower activity. Therefore widely
scattered to locally numerous showers, with a few thunderstorms are
forecast at different times through the local waters and islands.
With the expected wind flow, portions of eastern PR, the San Juan
Metro, and the northwestern quadrant of PR are favored to have the
most persistent showers and thunderstorms. Therefore, urban and
small stream flooding could be very possible in those areas on
Monday. Also, because of the increase in moisture, the heat index
values could increase to just over 105 degrees across north central
PR by the late morning into early afternoon hours, before the
cloudiness and shower activity cools things off a little bit in the
afternoon. Drier air and some Saharan dust may return on Tuesday.
This could slightly limit the shower and thunderstorm potential
across the local area. However, it will not completely eliminate the
chances, and therefore scattered shower and isolated thunderstorms
are still forecast for Tuesday afternoon. Otherwise the general
pattern will be typical, with most of the afternoon convection
occurring across western PR.

&&

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

The main feature for the long term period is the tropical wave/low
pressure system that is expected over the next weekend. This is the
feature that is being tracked by the NHC with a medium chance for
formation. But that feature is also a source of great uncertainty as
much as it a source of concern. Model guidance shows the system
moving by the islands to the northeast, but there remains some
difference in how far away, as well as in strength of the system.
With the 18Z run, the GFS had a weaker system tracking further from
the islands, while the 12Z Euro was a bit closer and stronger. As
was expected, the 0Z run of the GFS was weaker than the 18Z (as has
been the tendency with these model runs over time); it also moved
the system slightly further to the northeast. Other model guidance
(the Canadian (CMC/GEM) and German (ICON) models) also trended
towards the GFS. The CMC maintained a similar strength compared to
previous runs, which places it in between the GFS and Euro
solutions, but moved the system to the northeast. The 0Z Euro has
also backed off compared to yesterday`s 12Z run, as well as moving
the system northeastward from where it was; minimum pressure when
the system is lowest is now 1009 hPa in the Euro solution, compared
to 998 hPa in the 12Z run. Confidence that the system will be
relatively weak, and that it will pass by well to the northeast is
medium - much could change over the next several days. Regardless, a
weak system provides more uncertainty for conditions over the
region, as there is less confidence in where moisture will be in
relation to the low. This affects the forecast from Thursday night
through the weekend and into early next week.

All of this to say that this is a difficult and uncertain forecast,
starting late this workweek and into early in the next workweek.
Forecast confidence is low.

On Wednesday, patchy moisture near seasonal normals is expected to
be affecting the region. Winds will be shifting to be more out of
the east to possibly northeast. Seasonally typical conditions are
expected, and afternoon convection is likely to affect western and
interior portions of Puerto Rico, and possibly into southwestern
sections.

Drier air is forecast to move into the region on Thursday, ahead of
a weak disturbance Thursday night into Friday. Shower activity is
still likely, though inhibited, and then increasing overnight.
Friday and Saturday look to be a little drier, with model guidance
showing a dry slot over much of the region. The exception here being
over the Atlantic waters, with the potential for the moisture to
reach the islands, especially in the north. The forecast reflects
something akin to climatology due to the potential that conditions
could be either wetter or drier depending on a lot of factors with
the passage of the low. Moisture increasing over the region becomes
more likely early next week.

&&

.AVIATION...
(12Z TAFS)

Generally VFR conds expected. SHRA across the flying area will
cause VCSH at most of the local terminals through 28/15Z. ISOLD
TSRA may cause at least VCTS at TJSJ and TJBQ after 28/15Z. Mtn
top obscr due to aftn convection over the interior sections of PR.
SFC winds from the east at around 10-15 kts with sea breeze
variations and a few gusts... winds decreasing after 28/23Z.

&&

.MARINE...

Moderate to locally fresh easterly winds will sustain some choppy
conditions across the waters. In some portions of the Atlantic
waters, wind speeds to near 20 knots are expected during the day
today. Seas of generally 3 to 5 feet or less are expected.

There is a moderate risk of rip currents for beaches of San Juan and
vicinity and westward along the northern coast of Puerto Rico, as
well as for eastern St. Croix. Elsewhere, the rip current risk is
low.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...None.
VI...None.
&&

$$

SHORT TERM...JA
LONG TERM....CRS
AVIATION...MMC

[cycloneye]

From the Antigua/Barbuda NWS.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
447 AM AST Mon Aug 29 2022

...New SYNOPSIS, AVIATION, MARINE...

.SYNOPSIS...
Issued at 335 AM AST Mon Aug 29 2022

A weak tropical wave will move into the local area today, causing
an increase in moisture. The increase in moisture with the
expected daytime high temperatures, may cause heat index values up
to 111 degrees across the coastal areas of northern and western
PR, and thus a heat advisory is in effect. Showers and
thunderstorms are expected this afternoon across the northwestern
quadrant of PR and portions of the San Juan Metro. Drier air with
some Saharan dust will move in on Tuesday and Wednesday.

&&

.SHORT TERM...Monday through Wednesday...

A weak tropical wave continues to push moisture over the region.
This has resulted in showers and thunderstorms over the local waters
through the night and into this morning, with some showers moving
onshore from time to time. This will continue into Tuesday, likely
into midday in the east and through the afternoon in the west. This
will help to maintain near-normal levels of moisture, supporting
shower activity. A typical pattern of activity is expected for the
next couple of days. An east-southeasterly flow will result in
showers and isolated thunderstorms for northwestern and interior
portions of Puerto Rico today, while more easterly winds are
expected tomorrow, resulting in peak afternoon convection over
western and interior areas. In the east, streamer activity is
likely, including for parts of the San Juan metro area.

Drier air moves in late Tuesday, remaining over the region on
Wednesday. Still, patchy moisture will help to maintain shower
activity. Aloft, the mid-level ridge will remain in place, resulting
in stability over the area. However, a strengthening upper-level low
is forecast to shift southwestward to just east of the islands and
linger there for Wednesday. This will combine with patchy moisture
to inhibit the decrease in shower activity for the afternoon.

Additionally, some lightly hazy conditions are anticipated, with a
small amount of Saharan dust moving in over the region starting on
Tuesday.

&&

.LONG TERM...Thursday through Monday...

The weather pattern in the long term forecast will be heavily
influenced by the development and eventual track of a tropical
wave (91L) that is currently around 46W. The long term forecast
took into account the inherited analysis as well as the latest
guidance, given that the models have been so inconsistent over the
past several runs and days, and uncertainty is higher than normal,
the changes made to the long term forecast were relatively minor.

The latest guidance suggests relatively dry air and NE winds on
Thursday into Friday, with winds decreasing and becoming variable
late Friday into Saturday. This is because the latest guidance
suggests a possible tropical cyclone several hundreds of miles to
the NE of the local islands by late Friday and Saturday. In fact,
if the model guidance were to verify, we will remain on a relative
dry slot through the weekend, with moisture increasing on Monday.
So given the latest guidance, the expected weather would be
mainly locally induced showers and thunderstorms over PR when the
available moisture combines with the local effects and the diurnal
heating. The location of the afternoon thunderstorms over PR will
depend on the prevailing wind flow. Currently, the afternoon
convection is forecast to be across central, west to SW PR on
Thursday and Friday, then central to northern PR on Saturday and
Sunday, then NW PR on Monday. For the USVI, mainly isolated to
scattered but brief showers would be expected.


Again, that is depending on the actual development of this
system, and we must monitor the official forecasts from the
National Hurricane Center regarding this disturbance. Therefore,
the long term forecast may see some changes in the next couple of
days, as we make adjustments considering the official forecast
from the National Hurricane Center regarding the track of this
disturbance, which again, is currently forecast to pass several
hundreds of miles to the NE of the local islands late this week
into the weekend.

&&

.AVIATION...
(06Z TAFS)
Issued at 335 AM AST Mon Aug 29 2022


Generally VFR conditions are expected over the next 24 hours across
all aerodromes. However, brief MVFR cannot be entirely ruled out due
to SHRA/TSRA, especially 29/17-23Z at TJBQ and TJSJ, when VCTS are
expected. Winds pick up after sunrise out of the east at 10 to 15
knots, with sea breeze variations and stronger gusts, especially
near SHRA/TSRA. After sunset, winds diminish again.

&&

.MARINE...
Issued at 335 AM AST Mon Aug 29 2022

Moderate winds up to 15 knots and seas of 4 feet or less are
expected today across the local waters. That being said,
relatively tranquil conditions are expected for the rest of the
workweek. Winds and seas are expected to diminish from Tuesday
night into Wednesday, as a high pressure in the western Atlantic
develops, causing lighter ENE winds.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...Heat Advisory from 10 AM this morning to 4 PM AST this afternoon
for PRZ001-005-008-010.

VI...None.
&&

$$

SHORT TERM...CS
LONG TERM....JA
AVIATION...CS

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
451 AM AST Tue Aug 30 2022

...New SYNOPSIS, AVIATION, MARINE...

.SYNOPSIS...
Issued at 355 AM AST Tue Aug 30 2022

Drier air with Saharan dust is expected to gradually move in
today. However, afternoon showers and thunderstorms are still
expected today. The winds are also expected to shift to a more
easterly direction, with ENE winds by late this afternoon,
continuing into Wednesday. Due to a SFC high pressure across the
western Atlantic and the tropical disturbance close to 50W that is
expected to move NW and remain to the NE of the Leeward Islands.
Heat index values are expected to be above normal again today,
with northern to western PR having the highest values which could
range between 108 and 111 degrees. Therefore a heat advisory is
in effect today. Tranquil marine conditions are expected today.

&&

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

Lingering moisture will continue over the area today, mostly in the
form of patchy moisture streaming across the islands. This will help
to support shower activity. However, drying is expected later in the
day, starting around midday int the east, and in the late afternoon
for some western portions of the region. This drying will occur as
the wind direction shifts, becoming more northeasterly over the
region. This shift will likely result in the afternoon convection
drifting southward somewhat. As such, early afternoon convection
will likely be concentrated over western and interior portions of
Puerto Rico, with southwestern areas possibly affected by late
afternoon.

Drier air will remain in place over the region through at least
Wednesday. Patchy moisture with near-normal precipitable water
values will still help to maintain a typical shower pattern over the
region. However, shower activity will be less than in previous days.
Mid-level ridging will remain in place through the period, providing
stability, which will also inhibit convective activity across the
region. During this time, the 500 hPa temperature is forecast to
warm, reflecting this increased stability. At the upper-levels, a
trough is expected to strengthen to the north/northeast of the
region, and then settle over the area late Wednesday into Thursday.
This could help promote some instability over the region, but its
impact could be limited with the mid-level ridge remaining in place.

Around midday on Thursday, a band of near-normal moisture is
forecast to arrive. This looks to be some moisture off of an old,
decayed frontal boundary pushed ahead of what is currently Invest
91L, the disturbance being tracked by the NHC with a medium to high
chance for formation over the next 2 to 5 days. As an aside, it is
worth noting that that disturbance is forecast to pass by the area
to the northeast, with limited impacts to the islands. But back to
within the short-term period, an increase in shower activity is
expected with this weak band of moisture for the second half of the
day on Thursday, with lingering moisture into the night. This
activity will be in a typical pattern; the northeasterly flow will
persist over the region, and as such the peak in afternoon
convection will affect southwestern and interior portions of Puerto
Rico. There is also the potential for streamer activity in the east,
though it is unlikely to affect the San Juan metro area given the
wind direction (though passing showers will still be a concern
there).

On the whole, decreasing shower activity is expected into midweek,
followed by a modest increase in activity for Thursday. Above normal
temperatures will continue today, and heat indices to near 110 are
anticipated. As such, a Heat Advisory is in effect for most of the
northern coast of Puerto Rico, from San Juan and vicinity westward,
as well as along the northern half of the western coast of Puerto
Rico.

&&

.LONG TERM...Friday through Tuesday...

There is now more agreement among the different model guidance and
also from one run to another. Overall, it seems as though the
expected weather in the long term will still be generally due to
local effects and diurnal heating. This means that the afternoon
convection is likely to occur in areas of sea breeze convergence.
The current Invest 91L is forecast to strengthen and move to the
NW, staying well to the NE of the local islands by Friday night,
then north of the local islands through the weekend into early
next week. With this track, we will remain in a relative dry slot
with light winds. Thus, the locally induced shower activity
expectation in the afternoons. There is however an increase in
moisture that is forecast for Monday, which may increase the
coverage of the shower activity across the local islands, but this
increase in moisture will be short lived, as drier air makes a
return on Tuesday.

&&

.AVIATION...
(06Z TAFS)
Issued at 355 AM AST Tue Aug 30 2022

Generally VFR conditions are expected across all aerodromes for the
next 24 hours. VCSH are expected to have limited to no operational
impacts at aerodromes. Afternoon convection will shift southward
later in the afternoon, and as such brief MVFR from SHRA cannot be
entirely ruled out for TJPS. Winds pick up after sunrise, out of the
east at 10 to 15 knots, with sea breeze variations and stronger
gusts. After sunset, winds will diminish, becoming light
overnight.

&&

.MARINE...
Issued at 355 AM AST Tue Aug 30 2022

Marine conditions are expected to be tranquil today with seas up
to 4 feet and winds up to 15 knots. There is also a low risk of of
currents across all of the local beaches. These marine conditions
will improve further by tomorrow, as lighter winds are expected.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...Heat Advisory from 10 AM this morning to 4 PM AST this afternoon
for PRZ001-005-008-010.

VI...None.
&&

$$

SHORT TERM...CS
LONG TERM....JA
AVIATION...CS

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
456 AM AST Wed Aug 31 2022

.SYNOPSIS...
Issued at 345 AM AST Wed Aug 31 2022

Surface high pressure across the western Atlantic, and the low
pressure across the central Tropical Atlantic (91L) is causing
light northeasterly winds across the local area today. Saharan
dust is expected today, causing hazy skies. Afternoon convection
is likely across the interior, west and southwestern portions of
PR. The marine conditions will be tranquil today and there is a
low risk of rip currents.

&&

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

Additional drying is expected today, especially over eastern
Puerto Rico and the USVI. Total precipitable water imagery from
GOES-16 shows that there is drier air to the east, approaching the
USVI this morning, with precipitable water values that are on the
order of 1.25 to 1.35 inches, which would be below seasonal
normals. However, there is some patchy moisture embedded in this
drier airmass, which will help to sustain some level of shower
activity still. This afternoon, however, additional moisture from
a weak disturbance will push over western Puerto Rico from the
north/northeast. As such, active weather is expected due to
afternoon convection, mostly for southwestern and interior
portions of Puerto Rico. Instability is decreasing however,
reflected in 500 hPa temperatures warming slightly from previous
days; the 0Z sounding showed temperatures had already warmed, to
-6.5C, and additional modest warming is forecast. With drier air
over the region during the morning, this will allow for good
daytime heating to fuel afternoon convection as well. Though it is
worth noting that slightly cooler temperatures are forecast for
today, with the wind having shifted to be more east- northeasterly
over the region.

A decrease in activity is expected for Thursday with dry air
remaining over the region. Starting Thursday evening, though, a weak
disturbance will push a band of moisture over the area. As such,
shower activity is expected to increase modestly for Thursday night
through the day on Friday.

&&

.LONG TERM...Saturday through Wednesday...

The general model agreement continues, and also the consistency
from one model run to another. Therefore there seems to be a bit
more confidence in the long term forecast, though still not more
confidence than normal for a long term forecast. The biggest
takeaway from the expected weather in the long term is that it
will be generally due to local effects and diurnal heating. This
means that the afternoon convection is likely to occur in areas of
sea breeze convergence. Also,the winds will be very light, as the
current low pressure (91L) in the central Atlantic will move
north of the local islands, leaving the local area with a very
weak pressure gradient from Saturday onward. That said, the winds
will be generally southerly to southeasterly on Monday and
Tuesday. The available moisture during the long term will be near
normal, but an increase in moisture is forecast for Monday,
possibly lingering into Wednesday. With this light wind pattern,
the areas of sea breeze convergence over PR will likely be mainly
across the interior, with thunderstorms developing later on with
the outflow from the initial thunderstorms that develop in the
afternoon. The USVI will remain mainly with a slight chance of
showers, likely observing little measurable precip for the most
part, with the chances of rain increasing early in the upcoming
workweek.

&&

.AVIATION...
(06Z TAFS)
Issued at 345 AM AST Wed Aug 31 2022

Generally VFR conditions are expected at all aerodromes for the next
24 hours. However, brief MVFR or worse cannot be entirely ruled out
for TJPS 31/17-23Z due to SHRA/TSRA, though most activity will stay
N and W of aerodrome. Winds pick up out of the E/ENE after sunrise,
with speeds 10 to 15 knots, then decrease after sunset, becoming
light overnight.

&&

.MARINE...
Issued at 345 AM AST Wed Aug 31 2022

Light winds, up to 10 knots are generally expected today, and up
to 15 knots tonight. Seas at 4 feet or less. Therefore tranquil
marine conditions are expected today. There is also a low risk of
rip currents across all of the local beaches.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...None.
VI...None.
&&

$$

SHORT TERM...CS
LONG TERM....JA
AVIATION...CS

[cycloneye]

Area Forecast Discussion...UPDATED
National Weather Service San Juan PR
457 AM AST Thu Sep 1 2022


.SYNOPSIS...Saharan dust continue to linger across the local area
today in lower concentrations. Light to moderate winds will
prevail for the next several days. Expect the development of afternoon
showers and isolated thunderstorms mainly over the central
interior and northwestern portions of Puerto Rico today. The low pressure
Invest 91L is located east of the Leeward islands and is expected to
mover north of the local islands by the weekend. No direct
impacts and threats are anticipated at this time.


&&

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

Saharan dust continue to linger across the local flying area
although in lower concentrations. A surface high pressure spread
across the west and central Atlantic, and a broad area of low
pressure (Invest 91L) will maintain a light to moderate
northeasterly wind flow across the region through the Friday. This
feature is forecast to continue to disrupt the overall steering flow
through the period as it moves west northwest and well northeast and
north of the area trough Saturday. At the upper levels, a Tutt low
and associated weak trough will continue to sag just north and west
of the region through Friday. It is to then erode by Saturday as an
upper ridge will build and spread across the region from the east.
This trough will aid in enhancing early morning passing showers and
also the development of afternoon showers and isolated thunderstorms
mainly over Puerto Rico today and on Friday aided by local effects
and daytime heating. Areas to be mostly affected should be focused
over parts of the central interior and west to southwest sections of
Puerto Rico and mainly downwind of the USVI where only isolated
afternoon showers are forecast. This afternoon rainfall, along with
could result in ponding of water on roads and in poor drainage areas
as well as urban and small stream flooding, with frequent lightning
and gusty winds with the strongest thunderstorms. Mudslides will
also be possible in areas of steep terrain due to loose soil from
previous days rains.

On Friday, as the strong tropical wave (91L) continues to move east-
northeast of the Lesser Antilles and north of the region, a slot of
drier air is expected to filter in. This should limit the available
moisture for widespread afternoon convection, however still expect
periods of early morning passing showers to affect the north and
east coastal areas of the islands. The proximity of the upper level
trough along with strong diurnal heating and local effects, expect
yet another round of afternoon showers and thunderstorm is in
isolated areas across the interior and southwest. Temperatures will
continue to be seasonably warm, with highs reaching the upper 80s to
near 90 degrees at coastal and urban areas, and heat indices
generally climbing to upper 90s to around 100 degrees through the
period.

On Saturday recent model guidance continued to be more consistent
and were in better agreement as far as the over track of AL91 as it
moves northeast then north of the region. Therefore although do
expect some peripheral moisture to propagate east and then southward
across the region over the regional waters from time to time, expect
for the most part passing morning showers with some locally heavy
along the north and east coastal areas but brief , followed by
mainly locally and diurnally induced afternoon convection mainly
over the central and west interior sections of Puerto Rico as the
steering flow is to gradually change and become fairly light and
variable as the pressure gradient will continue to weaken across the
region during the afternoon. The northern USVI may also brief
afternoon showers while St Croix is so far expected to see lesser
amounts but isolated convection cannot be ruled out at this time.

&&

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

A potential tropical system located east of the Leeward Islands will
be north-northeast of the local islands by Sunday, promoting a
southeasterly wind flow. This system will provide instability
aloft and will increase the potential for thunderstorm
development, especially over the central interior and northwestern
Puerto Rico. Since the wind flow is from the southeast, expect
high temperatures across the northern coast of Puerto Rico and the
U.S Virgin Islands. By Monday through Tuesday, drier conditions
will dominate across the local islands. However, afternoon
convection is likely to occur generally due to local effects and
diurnal heating, mainly across the central interior, western, and
northwestern Puerto Rico. By Wednesday onwards, moisture pulled
from the Caribbean is expected to reach the local area, enhancing
the potential for showers and thunderstorms. Winds will start to
shift to a more east-southeast flow. The U.S. Virgin Islands will
remain mainly with a slight chance of showers, with the chances of
rain increasing early in the upcoming workweek.

&&

.AVIATION...VFR at all terminals durg prd. However SCT-BKN lyrs nr
FL025...FL050 with wdly SCT SHRA to affect the regional waters and
VCSH at TJSJ/TJBQ/TIST/TISX 01/14Z. Brief mtn top obscr psbl ovr Ern
PR due to passing SHRA and Low clds. TSRA/SHRA will develop across
the the interior, west and southern slopes of PR btwn 01/16-23z.
This activity may again result in brief mtn obscr and MVFR/IFR conds
at TJMZ/TJPS where VCSH/VCTS will be possible. SFC wnds light/vrb
bcmg returning fm NE at 10-15 mph with sea breeze variations and
occasionally hir gusts durg the aftn and with aftn TSRA. No other
sig operational wx impacts attm.

&&

.MARINE...Light to moderate northeasterly winds will prevail for next
several days. Mariners should expect relatively tranquil with seas
up to 4 feet. For beachgoers across the local beaches, there is a
low rip current risk everywhere.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...None.
VI...None.
&&

$$

SHORT TERM...RAM
LONG TERM....GRS

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
338 AM AST Sat Sep 3 2022

.SYNOPSIS...Tropical Storm Earl is expected to move north of the
local islands on Sunday. The outer bands of Earl are expected to
bring showers and thunderstorms to Puerto Rico and the Virgin
Islands through early in the workweek. This will increase the risk
of flooding and mudslides for the next several days. For most of the
next workweek, a light and moist southerly wind flow is expected to
prevail, resulting in active afternoon mainly across the Cordillera
Central and northern Puerto Rico.

&&

.SHORT TERM...Tonight through Monday...

A surface high pressure across the central Atlantic in combination
with Tropical Storm Earl located northeast of the Leeward Islands
will maintain a moderate northeasterly wind flow across the region
today. By late this evening, winds will become more from the south-
southwest as the cyclone moves north of the local area.

Although the tropical storm wind field is expected to remain over
the offshore Atlantic waters, the outer bands of Earl will continue
to result in periods of heavy rainfall and thunderstorms across the
U.S. Virgin Islands and the eastern, northeastern, and southeastern
portions of Puerto Rico during the morning hours. Thereafter, expect
an increase in the potential for heavy rainfall and thunderstorms
for the central interior, western, and southern of Puerto Rico
throughout the day. These conditions could lead to ponding of water
on roads and in poor drainage areas, as well as urban and small
stream flooding with the strongest thunderstorms and heavy rains
over PR. Mudslides are also possible in areas of steep terrain
across parts of the central and west sections of Puerto Rico.

Unstable weather conditions will continue on Sunday. With the shift
in the wind direction to a more south-southwest component the
rainfall and thunderstorm activity will concentrate in the northern
portions of Puerto Rico, including the metropolitan area of San
Juan. The U.S Virgin Islands are expected to receive showers from
time to time. As the Tropical Storm moves off to the northeast and
north of the islands more abundant tropical moisture will continue
to enter to the local area.


&&

.LONG TERM...Tuesday through Saturday...

The same story repeats for the long-term forecast period. Tropical
Storm Earl will maintain a moist and light southerly flow over the
northeastern Caribbean through at least Wednesday. This will
translate in showers moving from the Caribbean across the southern
municipalities of Puerto Rico as well as the U.S Virgin Islands. In
the afternoon, if enough sunshine is available, afternoon activity
is expected to fire up, but focusing along the Cordillera Central
and northern Puerto Rico, including the San Juan metro area. Due to
the expected light winds, the showers and thunderstorms are expected
to last longer, resulting in an increased risk of urban and small
stream flooding, as well as mudslides in areas of steep terrain.

By the latter part of the workweek, the forecast becomes a little
more uncertain, as the GFS shows a stronger Earl moving
northeastward and creating southwesterly flow over the local
islands, while pulling moisture from the south. The ECMWF shows a
slower and weaker system meandering north of the local islands.
Regardless of the future of the system, a wetter weather pattern is
favored once again across the islands. Since this forecast is
dependent on the track, intensity and forward speed of Earl, the
uncertainty is higher than normal, so the users are advised to stay
tuned to the evolution of the forecast.

&&

.AVIATION...SHRA and TSRA will increase over the PR and USVI
terminals through 03/22z. The outer bands of Tropical Storm Earl may
cause brief MVFR cigs across the local terminals. VCTS/VCSH expected
for the TJSJ/TIST/TISX terminals after 03/14Z. Afternoon TSRA/SHRA
development will result in VCTS/VCSH for TJPS 03/16Z and VCTS/VCSH
for TJBQ between 03/17-23Z. Winds will continue from the NE at 10
kts or less, increasing to 10-15 knots with higher gusts after
03/14Z.

&&

.MARINE...Tropical Storm Earl will maintain hazardous seas along
the offshore waters through Sunday. Seas up to 8 feet are
anticipated. The storm will bring squally weather across the
entire area of responsibility, with locally higher seas and winds
within the thunderstorms. Winds close to tropical storm strength
will be possible across the northeast corner of the offshore
Atlantic waters (AMZ 710). For the beaches, the risk of rip
currents is moderate, and could increase to high on Sunday.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...None.
VI...None.
&&

$$

SHORT TERM...RAM/GRS
LONG TERM....ERG
PUBLIC DESK...CVB

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
427 AM AST Wed Sep 7 2022

.SYNOPSIS...

Another round of an active weather pattern is forecast for today, as
plenty of moisture keeps the potential for shower activity high.
This in turn will bring a significant risk for flooding and
mudslides in northeastern sections of Puerto Rico. For the rest
of the area, the flood threat will remain elevated. Weather
conditions are forecast to improve as the week progresses and
less shower activity is likely from Sunday onward. A heat
Advisory is in effect from 10 AM AST to 4 PM AST across the north,
west and northeast areas today. At upper levels high pressure is
centered over Puerto Rico and will drift slowly northwest during
the period.

&&

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

Hurricane Earl is expected to continue north for a few more hours
and then northeast for the remainder of the period. As it
continues to distance itself from the area, the local surface and
low-level winds--from the south today--will slowly back to the
southeast and east southeast during the period. Moisture will
remain above normal today through Friday, but will be less than
yesterday. This plus the southerly flow, will allow temperatures
to rise a little more today with delayed convection. This
additional heat is expected to offset the weaker moisture and
generate another round of heavy showers and isolated to scattered
thunderstorms across interior and north central through
northeastern sections of Puerto Rico. Rainfall amounts of 1 to 4
inches, and locally higher, are expected to generate some
flooding in the northeastern and northern interior portions of
Puerto Rico today. It is also possible that a convergence band
will also re-form east of Puerto Rico and produce more rain for
the U.S. Virgin Islands. As the southerly flow gains an easterly
component on Thursday, the focus of the heaviest rainfall will
shift west across the northern half of the island of Puerto Rico.
The U.S. Virgin Islands will have scattered showers over them and
the surrounding waters. By Friday the heaviest rains will fall in
the afternoon over north central and northwest Puerto Rico, but
scattered showers can still occur elsewhere. At upper levels high
pressure is centered over Puerto Rico and will drift slowly
northwest during the period. An increase in northeast winds at
upper levels should also mean extra afternoon sun for the eastern
third of the island and a longer period of heat on Friday.

&&

.LONG TERM...Saturday through Wednesday

An important surface pattern transition will occur on Saturday
across the county warning area as Hurricane Earl migrates more
into the northeastern Atlantic. This pattern will lead to more
east-southeasterly wind flow across the area, and the typical wind
pattern will return for the forecast area. Embedded in this wind
flow, plenty of tropical moisture with precipitable waters values
above climatological normals will reach the islands keeping the
potential high for flooding and thunderstorms. Therefore, on
Saturday into Sunday, daily rain chances are forecast with
isolated to scattered showers during the morning hours across the
local waters and along the coastal areas. After that, heavy
afternoon convection is expected to develop across the interior
and northwestern sections. Given the soils saturated conditions,
the primary threats are localized flooding, especially in
saturated areas.

A slight change in water content will limit the shower activity on
Monday, when a dry airmass slot filters in. Although conditions are
not favorable for widespread activity, the lack of moisture
countered by better instability will lead to the usual afternoon
activity across the interior and western Puerto Rico. Isolated
thunderstorms can not be ruled out with the heaviest activity.
Patches of moisture embedded in the trade winds will result in a
diurnal convective cycle on Tuesday into Wednesday with isolated
to scattered showers and thunderstorms forecast during the
afternoon. The best coverage is again forecast to develop over
the interior and northwestern sections, as well the San Juan Metro
area. On Tuesday, an upper level trough will deepen just north of
the region and will likely increase the potential for
thunderstorms with the heaviest activity. Additionally, on
Tuesday, temperatures at 500 MB will range between 7 to 8 Celsius
degrees. Daytime temperatures will remain around the upper 80
degrees and the lower 90s across the coastal areas, with heat
indices around 100-105 degrees each day.

&&

.AVIATION...
(06Z TAFS)

VFR conditions to prevail til arnd 07/16Z. Then SHRA and sct TSRA
will dvlp across central and ern PR north of the Cordillera
Central with mtn obscurations and MVFR/IFR conds. TSRA should
dissipate by 07/21Z ovr PR and by 08/02Z ovr the lcl waters. Sfc
winds southerly less than 12 kts except hir gusts nr SHRA/TSRA.
Some sea breeze influences are expected today. Max winds west
18-22 kt btwn FL150-190.

&&

.MARINE...

Relatively tranquil marine conditions will remain for the next two
days. Seas are forecast to remain up to 5 feet across most of the
outer waters and up to 4 feet across the coastal waters. Winds
will continue from the south at 15 knots with gusty winds near the
heaviest shower activity. With the heaviest activity, isolated
thunderstorms and gusty winds cannot be ruled out today. There is
a moderate risk of rip currents across all the north, west, and
east coast of Puerto Rico, Culebra, and Saint Thomas.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...Heat Advisory from 10 AM this morning to 4 PM AST this afternoon
for PRZ001-002-005-010.

VI...None.
&&

$$

SHORT TERM...WS
LONG TERM....LIS
AVIATION...CRS

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
531 AM AST Thu Sep 8 2022

.SYNOPSIS...

A more southerly wind flow is expected for today with plenty of
tropical moisture. This will increase the chances for another
active afternoon. Shower activity is already underway in the south
but warmer temperatures and heat indices in the 102 to the 109
degrees Fahrenheit range are forecast for the north central to
the northeastern coast of Puerto Rico. Therefore, there is a heat
advisory in effect for these areas from 1000 AM through 4 PM AST.
Winds will shift to the east southeast over the weekend and
shower activity will focus on the western side of Puerto Rico then.
Above normal moisture will continue into early next week.

&&

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

A marked change in the surface pattern is forecast for today, as
Hurricane Earl continues his route to the northeastern Atlantic and
results in a more southerly wind component. This wind flow will
continue to feed the area with plenty of tropical moisture, with
precipitable water values around 2.1 inches, which is above the
climatological normal. The latest Galvez-Davison Index (GDI)
shows favorable conditions for scattered thunderstorms each day.
As expected, the diurnal and local effects will translate into
another round of heavy activity with periods of scattered
thunderstorms especially across the Cordillera Central and north
central Puerto Rico. The relaxed pressure gradient at the surface
will result in light winds for today. This will highly impact the
rainfall accumulations, increasing the flood threat. Therefore,
urban and small stream flooding, as well as some mudslides, can
be anticipated for this afternoon across portions of central to
northern Puerto Rico due to the already saturated soils.

Friday into Saturday, model guidance agrees with a noted shift in
the surface winds to the east-southeast as the influence of the
Hurricane Earl moves out and a building high pressure, squeezed
by another surface low, establishes itself over the central
Atlantic. This wind flow will return us to the typical weather
pattern for the islands. Therefore expect, passing showers during
the morning hours, followed by the deep convective activity across
the interior and northwestern sections of Puerto Rico each
afternoon. Although conditions are favorable for shower
development, widespread thunderstorms are not anticipated as a
mid-level ridge establishes over the area, limiting the vertical
motion and stability. However, expect urban and small stream
flooding, each day with the heaviest activity.

Temperature-wise, near to slightly above normal temperatures are
expected with highs from the upper 80s to low 90s across coastal
areas, and heat indices between 100-109 Fahrenheit degrees.

&&

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

Hurricane Earl will still be north northeast of the area on Sunday,
but his influence will be limited to weakening the subtropical
ridge in the lower levels over the western tropical Atlantic.
High pressure at the surface will have built into the southeast
central North Atlantic Ocean and this will serve to renew the
easterly trade winds in the forecast area. These winds will bring
areas of moisture interspersed with drier air. A low pressure that
moved off of Africa several days ago has some potential to
develop into a tropical system, but the GFS weakens it before it
reaches 50 west and it is expected to dissipate. Another system
that leaves Africa tomorrow is expected to pass south of the area
as a weak tropical wave on Thursday. Both of these systems will
contribute a little to the generally moist conditions already in
the area. At upper levels light northeasterly flow is expected to
prevail through Monday, then a long wave trough will stretch
toward the southwest from the north central Atlantic and generate
a TUTT low to our northwest. This should enhance thunderstorms
over the area Tuesday through Thursday as 500 mb temperatures
respond in synchrony by cooling.

Overall the trend is for drying, but showers and thunderstorms are
expected each day throughout the period. Because soils will be
quite soggy from previous rains the threat of mudslides will
linger well into the period.


&&

.AVIATION...
(06Z TAFS)

VCSH will prevail across TIST & TJPS at least til 08/15Z. After
that, SHRA and TSRA are fcst to dvlp across the Cordillera
Central and spread to north central PR resulting in periods of MVFR
conditions for most of the TAF sites with limited visibility,
lower ceiling, frequent lightning and gusty winds from 08/16Z thru
08/20Z. Winds will become more from the south today, at 12 knots
or less, with sea breeze variations. After 08/22Z, VCTS and SHRA
will affect TJBQ briefly. Winds will become light/VRB at 08/22Z
from the S-SE with land breeze variations.

&&

.MARINE...

Hurricane Earl will continue to send wave energy toward the
islands through the weekend, but wave heights will remain below 6
feet in the forecast area. This morning seas were 6-7 feet at the
outer buoy (41043) but those waves are deteriorating before
reaching the local area. Hurricane Earl is forecast to continue
strengthening which will generate stronger wave action. Current
wave models are developing higher seas that are expected to arrive
Monday night and Tuesday to exasperate a high risk of rip
currents and small craft advisories then.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...Heat Advisory from 10 AM this morning to 4 PM AST this afternoon
for PRZ001-002-005.

VI...None.
&&

$$

SHORT TERM...WS
LONG TERM....LIS
AVIATION...CRS

[cycloneye]

Area Forecast Discussion...CORRECTED
National Weather Service San Juan PR
546 AM AST Sat Sep 10 2022

.SYNOPSIS...Winds will continue to be more southeasterly today as
a surface high pressure establishes over the western into the
central Atlantic. Today, an area of moisture embedded in the
winds will increase the chances of showers and thunderstorms.
Drier air is expected to move over the area for the first part of
next week, resulting in a decrease in shower activity. Better
moisture is expected on by midweek.


&&

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

Another round of moisture is arriving in the region this morning,
and will help to sustain another active weather day over the area.
Winds are generally southeast/east-southeasterly, resulting in
convection over interior and northwestern Puerto Rico. In the east,
streamer activity is also expected to result in showers and isolated
thunderstorms, including for over the San Juan metro. Urban and
small stream flooding will again be a concern today.

Moisture decreases starting tonight, resulting in a decrease in
shower and thunderstorm activity. Still, moisture embedded in the
trade winds will make their way over the islands from time to time,
which will sustain some shower activity, in a typical pattern. This
slightly less wet pattern will continue on Monday.

&&

.LONG TERM...Tuesday through Saturday

The inherited forecast is still on track. The weak tropical wave will
continue to ingest the feeder band left by Hurricane Earl through
Tuesday. The winds during this first part of the workweek will be
from the southeast, meaning that most of the rainfall activity
will be concentrated along the northwestern quadrant of the
island. At the upper levels, there is a long wave trough to the
north of the area, which will cross the local area on Tuesday,
increasing the instability across the region. A second tropical
wave will introduce a moisture surge into the region by midweek.
During the middle part of the workweek, expect winds to turn more
easterly at the lower levels. This pattern will become typical,
but the convective activity and abundant moisture will keep most
areas wet across the islands. Expect a TUTT to return to the
forecast area by Friday. Nevertheless, showers and thunderstorms
could be seen daily through the end of the period. The main
threat is mudslides due to how saturated the soil is.

&&

.AVIATION...
(06Z TAFS)
Issued at 437 AM AST Sat Sep 10 2022

Generally VFR conditions are expected for the next 24 hours, though
brief MVFR cannot be entirely ruled out, especially during afternoon
convection for TJBQ and TJSJ. VCTS expected for TJSJ/TJBQ 10/17Z-
10/22Z. SHRA/TSRA expected afternoon for interior and northwestern
PR, and streamer in the east, including for San Juan metro. Winds
increasing after sunrise, becoming generally southeast at 10 to 15
knots, then subsiding after sunset.

&&

.MARINE...
Issued at 437 AM AST Sat Sep 10 2022

Seas are fluctuating from 2 to 4 feet across the local waters.
Expect a new pulse of swell from Hurricane Earl when it becomes a
major or near major hurricane on Monday and Tuesday bringing
hazardous seas and a high risk of dangerous rip currents to most
northern shores.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...None.
VI...None.
&&

$$

SHORT TERM/AVIATION...CRS
LONG TERM....MMC

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
531 AM AST Sun Sep 11 2022

.SYNOPSIS...

The forecast is still on track, a more typical summer
weather pattern will continue to prevail across the islands with
some dry air filtering and passing showers from time to time. Most
of the rainfall activity is forecast to occur during the
afternoon hours across southwestern sections Puerto Rico, with a
chance of thunderstorm activity across western municipalities. On
Friday, a tropical wave will increase rainfall across the region.
A strong northerly swell is expected early this week, resulting
building seas and hazardous marine conditions.


&&

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

An area of drier air is expected to continue to filter from the east
during the next few days. However, diurnally induced afternoon
showers with thunderstorm development is expected each day across
portions of the interior and western Puerto Rico. Across the USVI
and eastern PR, streamers should develop too due to local effects,
but better rainfall accumulations will favor convection further
west. Having said that, a Tropical Upper Tropospheric Trough (TUTT)
is expected to develop north and west of the area on Monday/Tuesday.
In response, the 500 mb temperature is forecast to drop to around
minus 7 degrees Celsius by 18z on Monday and favor divergence aloft
to promote a favorable environment for thunderstorm activity. Drier
air will continue to move ahead of the arrival of a weak tropical
wave on Tuesday. However, the precipitable water content (PWAT) is
not expected to drop below seasonal values till Tuesday morning,
where model guidance suggest a PWAT minima of near 1.35 inches.

Steering winds will have a northeasterly component today, and the
focus of afternoon convection is expected to remain over portions of
the Cordillera and west/southwest PR. Winds are then expected to
veer from the east to southeast on Monday/Tuesday, shifting the
focus of convection along the northern slopes and northwest quadrant
of PR. Urban and small stream flooding is likely with any heavy
afternoon thunderstorm activity.

Maximum temperatures will remain in the high 80s to low 90s and heat
indices will continue between 100F-108F across most urban and
coastal areas of PR through the short term period.

&&

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

The latest model run suggests a more typical weather pattern
through midweek. By midweek, expect winds to turn more easterly
at the lower levels. A more typical pattern will prevail, but the
convective activity and abundant moisture will keep most areas
wet across the islands. Expect a TUTT to return to the forecast
area by the end of the workweek. On Friday, conditions will
deteriorate as another tropical wave reaches the local islands.
Current PWAT models indicate 2 to 2.50 inches of rain each day
from Friday into the weekend. Currently, there is low to medium
confidence in the forecast regarding when conditions will improve
again. ECMWF model has most of the moisture content lingering
through the weekend, while the GFS is showing a gradual improvement
in conditions by Sunday into the beginning of the workweek. The
main threats with this rain event could be flooding in urban areas,
small streams, and mudslides due to how saturated the soil is.

&&

.AVIATION...Mainly VFR conditions are expected to prevail across
all terminals through the forecast period. However, SHRA/TSRA is
expected to develop btw 11/16-22z over west/southwest PR, and this
should cause mainly VCTS at TJPS/TJBQ with brief MVFR cigs
possible. East to northeast trades should increase btw 10-15 kts
with sea breeze variations and higher gusts aft 11/14z.

&&

.MARINE...Today seas will remain around 2 to 4 feet across the
local waters as gentle to moderate east-southeast winds prevail.
On Monday, expect a strong northerly swell to result in building
seas and hazardous marine conditions. Therfore, a high surf and
small craft advisory will be highly encourage to be added to the
forecast tomorrow as the event get closer to the region.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...None.
VI...None.
&&

$$

SHORT TERM/AVIATION......DSR
LONG TERM....MMC

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
546 AM AST Mon Sep 12 2022

.SYNOPSIS...Today, expect patches of moisture to filter into the
forecast area. Therefore, passing showers are expected across the
USVI and eastern PR during the morning hours, followed by
afternoon convection over the western portions of PR during the
afternoon hours. By Wednesday, a tropical wave will reach the
local area, enhancing the potential for heavy rainfall and
isolated thunderstorms.

&&

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

A Tropical Upper Tropospheric Trough (TUTT) is expected to develop
north and west of the area and linger over Hispaniola through
Wednesday. In response, cooler 500 mb temperatures are still
forecast to enhance divergence aloft and a favorable environment
for thunderstorm activity today. A mid-level ridge will also build
by Tuesday from the northeast and promote drier air ahead of a
weak tropical wave that should cross the region from late Tuesday
through Wednesday. Steering winds will shift from the east to
southeast during the short term period, and afternoon convection
will favor the northern slopes and northwest quadrant of PR. Urban
and small stream flooding is likely with any heavy afternoon
thunderstorm activity today. Maximum temperatures will remain in
the high 80s to low 90s and heat indices will continue between
100F-107F across most of the northern coastal municipalities of
Puerto Rico, and St. Croix. Passing showers and diurnally induced
afternoon streamers are expected across the USVI each day, with a
slightly drier trend of Tuesday.

&&

.LONG TERM...Thursday through Monday...

No significant changes have been introduced to the forecast. Late
midweek, a typical weather pattern will prevail, and expect winds
to become easterly-northeasterly at the lower levels. Although a
more seasonal pattern will stay, the convective activity and the
available moisture will keep most local areas wet across the
islands. By the end of the workweek, a TUTT will be across the
forecast area. On Friday, conditions will deteriorate as another
tropical wave reaches the local islands. Current PWAT models still
indicate 2 to 2.50 inches of rain each day from Friday into the
weekend. The low to medium confidence in the forecast regarding
when conditions will improve continues. ECMWF model still shows
most moisture content lingering through the weekend, while the GFS
is showing a gradual improvement in conditions by Sunday into the
beginning of the workweek. The main threats with this rain event
could be flooding in urban areas, small streams, and mudslides due
to how saturated the soil is.

&&

.AVIATION...Mainly VFR conditions are expected to prevail across
all terminals through the forecast period. However, SHRA/TSRA is
expected to develop btw 12/16-22z over western PR, causing tempo
MVFR to brief IFR conds at TJBQ. VCTS possible at TJSJ/TJPS during
the same period. East to southeast trades should increase btw
10-15 kts with sea breeze variations and higher gusts aft 12/14z.

&&

.MARINE...Seas are forecast to build up to 8 feet by this evening
due to a long period northerly swell. East winds around 15 knots
or less are expected to prevail. At least through mid-week, a
northerly swell will deteriorate marine and coastal conditions
across the Atlantic waters and portions of the local passages.
Small Craft Advisories will be in effect from this evening through
Thursday morning. At this time, there is a high risk of rip
currents across the north facing beaches of Puerto Rico. There
will be a high surf advisory in effect from this afternoon into
Wednesday. Please refer to the latest Coastal Hazard Message
(CFWSJU) for detailed information. Beachgoers and inexperienced
swimmers should avoid beaches with northern exposure through mid-
week.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...None.
VI...None.
&&

$$

SHORT TERM/AVIATION...DSR
LONG TERM....MMC

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
358 AM AST Tue Sep 13 2022


.SYNOPSIS...This morning, passing showers are expected to affect
the U.S. Virgin Islands and eastern Puerto Rico. In the afternoon,
most of the shower activity will be concentrated across western
Puerto Rico. By Wednesday, a weak tropical wave is forecast to
approach the local area. Expect an increase in showers and
thunderstorm activity. A strong northerly swell will continue
creating hazardous marine conditions for the next few days.

&&

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

An upper level low located north of Hispaniola will continue to
provide instability aloft through the day. At the lower levels,
moisture will decrease as a drier air mass filters from the east.
Recent satellite derived products show precipitable water values
around 1.3 inches, which is a little above of the global guidance.
Nevertheless, the pattern should favor the formation of afternoon
showers and thunderstorms along northwestern Puerto Rico, but it
will not be as widespread as yesterday. Regardless, these areas have
received plenty of rainfall in the past few days, and any additional
amounts may result in rapid river rises, mudslides and urban and
small stream flooding. The storms could be strong too, with periods
of frequent lightning and gusty winds.

By the end of the day, the upper level trough will weaken and lift
toward the northwest, losing influence over the local conditions. At
the same time, a mid-level ridge will build, creating fairly stable
conditions. However, att the low levels, a narrow band of moisture
associated with a wind surge will move in on Wednesday, quickly
followed by a pocket of dry air Wednesday evening and early
Thursday. This drier air mass also has slight amounts of Saharan
dust, so skies may look hazy at times.

Then, late on Thursday, a vigorous tropical wave begins to move
across the area. As the areas of moisture begin to filter in, expect
an increase in shower and thunderstorm activity across the region.
This wave is also being monitored by the National Hurricane Center
for tropical cyclone genesis, but the chances are low at this time.
Therefore, the main impact associated with this wave is going to
rain, spreading into the long-term period, along with gusty winds
with the rain activity.

&&

.LONG TERM...Friday through Tuesday...

Model guidance continues to suggest deteriorating weather conditions
by the end of the workweek, as the tropical wave approaches the
local islands. On Friday, winds are forecast to become stronger,
fluctuating from 15 to 20 mph and as it gets into the weekend,
expect the winds to weaken gradually. The wind flow will be out of
the northeast, meaning that most afternoon activity will focus on
the southwestern quadrant of Puerto Rico. The latest PWAT model
continues to show above-normal moisture content across the area,
with values reaching 2.50 inches of rain each day from Friday into
the weekend. The main threats with this rainfall event could be
flooding in urban areas, small streams, and mudslides due to how
saturated the soil is. Expect marine conditions to deteriorate
slightly across the north-facing local waters of the islands.
Nevertheless, the offshore waters will see up to 7 feet of wave
height until the first part of the weekend. There is still a low
to medium confidence in the forecast regarding when conditions
will improve. GFS model now shows some moisture content lingering
through the first part of the workweek, while the ECMWF shows a
gradual improvement in conditions by Monday.

From Tuesday onwards, expect a more typical weather pattern with
some trade wind showers and more localized convection across the
west and interior sections of Puerto Rico each afternoon. This
pattern is due to a mid-level ridge over the region that will
limit significant rainfall activity. During that part of the
workweek, an upper-level trough will also position across the
forecast area. Still, it is not expected to significantly
influence the forecast area, as it will not be close enough to the
region.

&&

.AVIATION...Mainly VFR conditions expected to prevail through the
forecast period. SHRA are moving along the USVI terminals, but no
operational impacts are expected. VCTS are expected for TJBQ after
17Z, which could result in periods of reduced VIS and low ceilings.
Mountain obscuration will be possible for the western side of the
Cordillera Central. Winds will be out of the east at 10 to 15 mph,
with stronger gusts.

&&

.MARINE...A strong northerly swell will continue to build seas
today. Most recent San Juan buoy indicates a swell of 8 feet at 14
seconds. East winds around 15 knots are expected to prevail. At
least through mid-week, this northerly swell will deteriorate
marine and coastal conditions across the Atlantic waters and
portions of the local passages. Small Craft Advisories are in
effect until Thursday morning. At this time, there is a high risk
of rip currents across the northern facing beaches of Puerto Rico
and the USVI. There is also a high surf advisory in effect until
Wednesday. Please refer to the latest Coastal Hazard Message
(CFWSJU) for detailed information. Beachgoers and inexperienced
swimmers should avoid beaches with northern exposure through mid-
week.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...Coastal Flood Advisory until 6 PM AST this evening for PRZ001-
002-005-008.

High Rip Current Risk through late Thursday night for PRZ001-002-
005-008-010-012.

High Surf Advisory until 6 PM AST Wednesday for PRZ001-002-005-
008-012.

High Surf Advisory until 6 PM AST Wednesday for PRZ010.

High Rip Current Risk through late tonight for PRZ013.

VI...High Surf Advisory until 6 PM AST Wednesday for VIZ001.

High Rip Current Risk through late Wednesday night for VIZ001.

High Rip Current Risk through late Wednesday night for VIZ002.

&&

$$

SHORT TERM/AVIATION...ERG
LONG TERM....MMC

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
441 AM AST Wed Sep 14 2022


.SYNOPSIS...

Today a wind surge and moisture bands will reach the forecast
region increasing chances for rain and thunderstorm activity. By
the end of the week, a tropical wave monitored by the NHC is
expected to affect our area leading to above normal moisture
content and more active weather conditions. A strong northerly
swell continues to affect our Atlantic Waters and local passages,
resulting in hazardous marine and coastal conditions. This swell
is expected to slowly subside throughout the rest of the week.

&&

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

Through the cycle, expect limited impacts from excessive heat
and wind but limited to elevated impacts from excessive rainfall
and lightning from afternoon convective development and the
passage of a broad tropical wave or Invest 96L. There are still
uncertainties regarding the evolution of Invest 96L, which remains
with a medium formation chance, based on the 2 AM AST Tropical
Weather Outlook issued by the National Hurricane Center. Any
tropical cyclone-related impacts in Puerto Rico and the U.S.
Virgin Islands will depend on whether this system becomes a
tropical depression in the next few days.

In the meantime, a mid-level ridge will continue to establish
to our north, generating stable conditions and unfavorable
conditions for deep convective development. At the lower levels,
winds will generally remain from the east at 10 to 20 mph. Still,
variations in direction and speeds will result from the passage of
a set of wind surges and the aforementioned tropical wave.
Accompanying each wind surge, bands of moisture will stream across
the area, causing total precipitable waters to peak at normal to
above-normal seasonal levels as high as 2.2 inches. Following a
drier air slot currently dominating the local islands, the first
band of moisture, expected to move across the region this
afternoon, will enhance locally and diurnally induced afternoon
convective development. So far, the strongest shower and
thunderstorm activity will focus across the interior to western
sections of Puerto Rico, where ponding of water on roadways and
poorly drained areas to localized urban and small stream flooding
is likely.

Drier air will invade the region tonight, leading to generally fair
weather conditions and limited shower activity. Yet, this will be
short-lived, with a second and broader band of moisture reaching
the area by Thursday, enhancing afternoon convective development
and overnight trade wind shower activity. After that, and based on
the most recent model guidance, Invest 96L will move over the
forecast area by Friday into Friday night, gradually causing
weather conditions to deteriorate with isolated to scattered
thunderstorms and gusty conditions. Once again, any tropical
cyclone-related impact will depend on the evolution of this
system. Interest in Puerto Rico and the U.S. Virgin Islands should
continue to monitor this system while evaluating their respective
Tropical Emergency Plans.

Daytime maximum temperatures are forecast to peak into the upper
80s to lower 90s each afternoon, with heat index values as high
as 102-107 degrees across lower elevations and some urban areas.

&&

.LONG TERM...Saturday through Wednesday...

Invest 96L is still forecast to bring some instability across the
area as the latest guidance suggests significant moisture content
through the weekend. The most updated PWAT model continues to
show above-normal moisture content across the region, with some
values reaching 2.50 inches of rain each day. On Saturday, winds
will peak, fluctuating from 17 to 28 mph, and as it gets into the
end of the weekend and early part of the workweek, expect the
winds to weaken gradually. The wind flow will be out of the east
southeast, meaning that most afternoon activity will focus on the
northwestern quadrant of Puerto Rico. Invest 96L is forecast to
affect most parts of the islands due to how disorganized the
system is. The main threats with this rainfall event could be
flooding in urban areas, small streams, and mudslides due to how
saturated the soil is. Expect marine conditions to deteriorate
slightly across the north-facing local waters of the islands.
Nevertheless, the offshore waters will see up to 7 feet of wave
height through the first part of the weekend. There is still a low
to medium confidence in the forecast regarding when conditions
will improve. GFS model now shows some moisture content lingering
through the first part of the workweek, while the ECMWF shows a
gradual improvement in conditions by Monday. Still, there is some
uncertainty with this system. Therefore, we urge the public to
stay informed with the latest updates from the National Hurricane
Center and your local weather forecasting office.

As mentioned in the previous forecasts, from Tuesday onwards,
expect a more typical weather pattern with some trade wind showers
and more localized convection across the west and interior
sections of Puerto Rico each afternoon. This pattern is due to a
mid-level ridge over the region that will limit significant
rainfall activity. During the workweek, an upper-level trough will
position across the forecast area. This trough is not expected to
significantly influence the forecast area, as it will not be close
enough to the region.

&&

.AVIATION...Mainly VFR conditions will prevail across all local
terminals through the cycle. Trade wind SHRA may result in brief
MVFR conditions at TJSJ, TJBQ, and USVI terminals through 14/14Z
and after 14/22Z. Afternoon SHRA/TSRA development could also
result in brief MVFR conditions at most terminals around
14/17-22Z. Except for TJPS, where winds will remain light and
variable, east winds will continue through the cycle, increasing
from 5-10 knots to 10-20 knots with higher gusts and sea breeze
variations after 14/14Z.

&&

.MARINE...The strong northerly swell will continue to affect the
local waters. Breaking waves up to 12 feet are expected across the
Atlantic waters. The San Juan buoy at 4:11 am showed a significant
wave height of 8 ft at 14.3 seconds. High rip currents and high
surf conditions are expected through Thursday for the northern,
western, and eastern beaches of Puerto Rico, Culebra, ST. Thomas,
and St. John. A high risk of rip currents is also in effect for
Vieques and St. Croix. A small craft advisory is in effect for
most northern local waters and local passages as hazardous marine
conditions continue. This swell is expected to slowly subside
throughout the rest of the week.

&&

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
529 AM AST Thu Sep 15 2022

.SYNOPSIS...Moisture accompanying a wind surge will reach the
region today, increasing locally and diurnally induced shower and
thunderstorm activity. Drier air will move into the area tonight
into Friday, but the expected weather scenario for Friday evening
into early next week will be linked to the passage of Tropical
Storm Fiona across the northeastern Caribbean. Tropical storm
conditions are possible as early as Friday night, but any
deviation from the current track and intensity forecast could
result in a different scenario. Except for excessive heat,
potential hazard risks will remain between elevated and
significant levels during this period.


&&

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

A decaying northerly swell continues generating hazardous coastal
conditions across the Atlantic Coastline due to dangerous breaking
waves and life-threatening rip currents. The dangerous breaking
waves affect the municipalities in Puerto Rico, from Aguadilla to
Fajardo and Culebra. The high risk of rip currents is for the exact
locations in Puerto Rico and the U.S. Virgin Islands.

Calm weather conditions will prevail early this morning with heat
indices above 100s Fahrenheit in urban and coastal areas. However, a
wind surge will increase showers and thunderstorms over the Virgin
Islands and the east half of Puerto Rico after mid-morning,
spreading across the west half of Puerto Rico by the afternoon.
Local effects, sea breeze variations, and diurnal heating will
promote the formation of strong thunderstorms in the afternoon,
especially across the southwest quadrant and interior sections in
PR. Downpours will result in ponding of water in roads and poorly
drained areas as well as urban and small stream flooding.

Subsidence ahead of Fiona will limit shower activity on Friday
morning. Nonetheless, the typical weather pattern will bring showers
embedded in the trades across the windward sections of USVI/PR,
followed by afternoon convection across the western sections of the
islands. In addition, heat index values may peak between 107 and 111
late in the morning and afternoon.

The discrepancy between ECMWF and GFS increased concerning the
intensity and trajectory, augmenting the uncertainty about the final
track and the possible impacts of Fiona in Puerto Rico and the U.S.
Virgin Islands. Based on the latest track and intensity forecast of
the National Hurricane Center, the outer bands of Fiona could begin
to arrive as early as late Friday night and slowly increase in
frequency and intensity by Saturday morning and afternoon. Fiona is
forecasted to be in her closest location to the U.S. Virgin Islands
and eastern Puerto Rico around Saturday morning or afternoon. Based
on the NHC forecast, we expect total rainfall accumulations of 3 to
6 inches with higher isolated amounts, hazardous marine conditions,
and Tropical Storm Force winds around Saturday. Please, actively
monitor the progress Fiona, as watches/warnings will likely be
required later today.

&&

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

The expected weather scenario for the long-term forecast period
remains uncertain since it will be linked to the evolution of
Tropical Storm Fiona. Despite variation in the most recent model
solutions regarding the future of Fiona, both global model
guidance suggests a persistent wet wetter pattern through the
cycle. This pattern, accentuated by an increase in showers and
thunderstorms extending beyond locally and diurnally induced
activity, will lead to elevated hazard risks from lightning and
excessive rainfall. Flash, urban and small stream flooding impacts
and mudslides in areas of steep terrain remain likely due to the
expected prolonged periods of moderate to heavy rains over already
saturated soils. Other potential hazard risks include excessive
heat, at limited to elevated risk levels, and winds, decreasing
from a significant risk level on Sunday due to the passage of
Tropical Storm Fiona across the region to limited risk levels
through the rest of the workweek.


&&

.AVIATION...VFR conditions are expected to prevail at all TAF
sites today with VCSH possible at E-PR/the USVI terminals
throughout the morning. SHRA/TSRA will develop across the
interior/SW PR, creating mountain obscuration and frequent
lightning between 15/16-22z. JPS/JBQ can expect mainly VCTS.
SHRA/TSRA may also result in brief MVFR conds across JSJ/IST btwn
15/16-20z. Winds will continue calm to light/VRB til 15/13z,
returning from the E-NE at 10 to 15 mph, with stronger gusts and
sea breeze variations.

&&

.MARINE...Dissipating northerly swells and moderate to fresh
winds up to 20 knots will maintain choppy seas up to 6 feet across
most of the local waters during the next few days. Thus, small
craft operators should continue to exercise caution. These swells
will continue to generate dangerous surf and life-threatening rip
currents conditions today for beaches across the north coast of
Puerto Rico and Culebra, where a High Surf Advisory and a High
Risk of Rip Currents remain in place.

Marine conditions will deteriorate by Friday afternoon into the
weekend as swells and wind-driven seas generated by Tropical Storm
Fiona affect the local waters. So far, a Small Craft Advisory is
in place for the offshore Atlantic waters.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...High Rip Current Risk through late Friday night for PRZ001-002-
005-008-012.

High Surf Advisory until 6 PM AST this evening for PRZ001-002-
005-008-012.

High Rip Current Risk through late tonight for PRZ010.

VI...High Rip Current Risk through this afternoon for VIZ001-002.

&&

$$

SHORT TERM...CAM
LONG TERM....ICP
AVIATION...ICP/CAM

[cycloneye]

Area Forecast Discussion...CORRECTED
National Weather Service San Juan PR
606 AM AST Fri Sep 16 2022

.SYNOPSIS...
Issued at 517 AM AST Fri Sep 16 2022

Tropical Storm Fiona continues moving westward, approaching the
Leeward Islands. Moisture ahead of Fiona is producing showers and
thunderstorms across the regional waters of the U.S. Virgin
Islands and Puerto Rico. Rain activity will persist throughout
the day, becoming more frequent late tonight and into the weekend
as Fiona moves closer to the islands. A Tropical Storm Watch is
in effect for PR/USVI, and could be upgraded to a Tropical Storm
Warning later this morning as Fiona moves closer.

&&

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

Moisture ahead of Tropical Storm Fiona is producing showers and
thunderstorms across the regional waters. The USVI and PR can
expect this wet and unstable weather pattern to continue
throughout the day, and rain activity will spread across the
interior and southwest quadrant of Puerto Rico during the
afternoon. Then, the outer bands of Fiona may affect the region,
producing squally weather as early as late tonight, increasing in
frequency and intensity by Saturday.

Based on the latest National Hurricane Center intensity and track
forecast Tropical Storm Conditions are possible within the U.S.
Virgin Islands beginning on Saturday and reaching Puerto Rico late
Saturday and Saturday night. However, heavy rains from Fiona will
spread across the USVI and PR Saturday into Sunday, producing
considerable flood impacts, including flash and urban flooding,
along with mudslides in areas of higher terrains. Therefore, a
Flash Flood Watch is in effect for the archipelago beginning this
evening and extending through at least Monday. As Fiona moves
northwestward, both the ECMWF and GFS models show pooling
abundant tropical moisture over the islands, which is likely to
promote an unstable and wetter pattern that continues behind
Tropical Storm Fiona and throughout the weekend.


&&

.LONG TERM...Monday through Friday...

If the projected track for Tropical Storm Fiona remains consistent
with the latest guidance, by early morning Monday, the core of
Fiona will be west of Puerto Rico, over the eastern half of the
Dominican Republic. Tropical-storm-force winds are still possible
across the western local waters as the storm exits completely out
of the CWA by late in the day. Marine conditions will remain
hazardous, especially across these waters as great sea heights and
thunderstorm activity will prevail. A significant amount of
rainfall is expected over the region for Monday throughout the
beginning of the week as the local atmosphere remains very
saturated and unstable from Fiona. Wind flow will prevail from the
southeast, favoring passing windward showers across the USVI and
eastern Puerto Rico followed by afternoon development across the
Cordillera Central into the western/northwestern quadrant of PR,
with streamer development affecting various eastern/northern
portions of Puerto Rico. Due to days of continuous rainfall, soils
across the islands will be very saturated and the probability for
flooding and landslides will be elevated.

A wet pattern will continue throughout the week, slowly easing to an
enhanced seasonal pattern by Wednesday. Precipitable water values
will remain above normal and will spike again at the end of the week
as another tropical wave moves over the region. A strong Tropical
Upper Atmospheric Trough (TUTT), associated with this tropical wave
may develop east of the region, which could support an unstable
atmosphere locally. The position of this upper level feature and
the intensity of the tropical wave will determine how much
rainfall will occur next weekend. Overall, for the long term
forecast, a wet pattern is expected with the greatest hazards
being urban and small stream flooding, isolated mudslides, and
daily thunderstorms.

&&

.AVIATION...
(12Z TAFS)
Issued at 517 AM AST Fri Sep 16 2022

SHRA will spread across the local airspace today. Winds will
continue from the NE at 5-15 kts with higher gusts/sea breeze aft
16/13z. Afternoon convection will develop across the mountain
areas and southwest PR btwn 16/18-23z. SHRA/TSRA will spread later
tonight as Fiona moves near the region. Based on the latest NHC
track/intensity forecast, tropical storm conditions are possible
across PR/USVI as early as this evening. The center of Fiona will
move near USVI by Saturday morning and near PR by Sat afternoon.

&&

.MARINE...
Issued at 517 AM AST Fri Sep 16 2022

Seas are currently below 6 feet across the forecast area. However,
marine conditions will deteriorate tonight as Fiona moves closer
to the region, with seas greater than 7 feet across the offshore
water. Wave heights will continue to increase in the entire area
if the track and intensity forecast from the National Hurricane
Center is verified. Tropical storm force winds may affect the
region as early as late tonight. Currently, 12-foot seas are
forecast to begin in the east of the Offshore Atlantic and the
Caribbean.

&&

.HYDROLOGY...

Based on the most recent guidance, the most likely time period for
the heaviest rainfall activity is Saturday into Sunday, while the
areas most likely to receive the highest rainfall accumulations are
portions of eastern Puerto Rico, where there is a potential for
rainfall totals to reach 6 to 8 inches with locally higher amounts
around 10 inches. Across southwest and south-central Puerto Rico
and the US Virgin Islands, the potential exists for rainfall
totals to reach 4 to 6 inches. Elsewhere, expect rainfall totals
to range between 2 and 4 inches.

Considerable flash and urban flooding impacts are possible across
eastern Puerto Rico on Saturday and Sunday. Across central and
western Puerto Rico as well as the US Virgin Islands, this
rainfall may produce limited flash and urban flooding impacts,
along with mudslides/rockfalls in areas of higher terrain. A
threat of flooding will continue into Monday--mainly in Puerto
Rico.

&&

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
538 AM AST Sat Sep 17 2022

.SYNOPSIS...
Tropical Storm Fiona started to affect the local islands with
numerous passing showers, strong winds, and thunderstorms across
the eastern half of the region. Conditions will further
deteriorate, with the most significant activity expected
throughout the weekend. So far, the eastern and southern sections
of Puerto Rico should see the worst winds and most rainfall based
on the latest track, but all of the area will see heavy rainfall.
A wet pattern will continue throughout early next week, slowly easing
to a more seasonal pattern.

Based on a strengthening trend, a Hurricane Watch is in effect for
today and tomorrow for Puerto Rico, the Caribbean Waters, and Mona
Passage. This is due to possible hurricane force winds when the
system moves closer to the islands.

&&

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

Tropical Storm Fiona continues to approach the local islands,
causing deteriorating weather conditions. The envelope of tropical
storm force winds is currently forecast to enter southeastern side
of the forecast area this morning, and the system is forecast to
continue to strengthen as it passes close to Cabo Rojo about a
day later. The GFS, which is fairly close to the official forecast
track for Fiona is showing a peak precipitable water of 2.7
inches on 18/12Z Sunday morning. Tropical Storm Fiona will exit
the forecast area around Monday morning. Significant rainfall is
anticipated with and behind this system, which will result in
considerable flood impacts, including flash and urban flooding,
along with mudslides in areas of steep terrain. Based on the
current forecast, eastern, southeastern, and southwestern Puerto
Rico should see the worst winds and rainfall, but the entire area
will see heavy rain. Additionally, tropical-storm-force winds are
expected to affect the area, with the strongest winds and gusts
along the Cordillera Central and southwestern Puerto Rico. The
activity will continue into Sunday, as the center of the storm
moves closer to western Puerto Rico and Fiona continues to
strengthen. For detailed information on Fiona`s impacts across the
island, track and projected intensities, please refer to the
Hurricane Local Statement (HLS) at www. weather.gov/sju.

On Monday, flow will be southeast at the surface and south southwest
at 700 mb and will be one of the main feeds of moisture and heat for
Tropical Storm Fiona. This will prolong showers and thunderstorms
across the area as well as some heavy rain. The threat of
flooding and mudslides will continue throughout the short term
period.

&&

.LONG TERM...Tuesday through Saturday...

By Tuesday, Tropical Storm Fiona will be well northwest of the
region and the threat of strong winds will have passed for the local
islands. However, numerous showers will continue throughout the
day, as generally southerly flow with prevail in the lower level,
blanketing the local atmosphere with saturated air. Stability
will be decreased post-Fiona, therefore thunderstorms are
expected throughout the week. Surface wind flow will prevail from
the southeast, favoring passing showers across the USVI and
eastern Puerto Rico followed by afternoon development across the
Cordillera Central into the western/northwestern quadrant of PR,
with streamer development affecting various eastern/northern
portions of Puerto Rico. Due to days of continuous rainfall, soils
across the islands will be very saturated and the probability for
flooding and landslides will be elevated.

A wet pattern will continue throughout the week, slowly easing to a
seasonal pattern. Precipitable water values will remain above normal
and then will decrease by Thursday into the weekend as patchy
moisture moves over the region. A strong Tropical Upper Tropospheric
Trough (TUTT) may develop east of the region on Friday, which could
support an unstable atmosphere locally. The position of this upper
low for today.level feature will determine how much rainfall
will occur next weekend. Overall, for the long term forecast, a
wet pattern is expected with the greatest hazards being urban and
small stream flooding, isolated mudslides, and daily
thunderstorms.

&&

.AVIATION...
Based on latest guidance from NHC, at 500 AM AST (0600 UTC), the
center of Tropical Storm Fiona was located near lat 16.4 deg N,
long 63.3 W. Fiona is movg twd the W nr 11 kts. Psbl max wnd
55g65 kt. Fiona is movg into the NErn Carib Sea and across the
lcl flying area fm arnd 17/06Z thru Monday morning. SCT SHRA/Isold
TSRA ovr rgnl waters and enroute btwn islands expected, bcmg
numrs aft 17/14Z. SFC wnd fm E 18-20 kts with hir gusts 25-35 kts
and ocnly hir with convective rain bands durg prd thru 17/10Z. Mtn
low for today.tops will be obscured ovr most of USVI/PR. Tropical
storm force winds are expected nr TISX by 17/13Z. Aft 17/14Z
tropical storm force winds and MVFR/IFR conds ovr a wide swath ovr
and south of the USVI/PR.

&&

.MARINE...
Hazardous marine conditions are forecast for all of the local
waters for the next several days as Tropical Storm Fiona moves
across the CWA. Therefore, a Tropical Storm Warning is in effect
for Puerto Rico, the U.S. Virgin Islands, and all the local
waters. A Hurricane Watch is also in effect due to a possible strengthening
of the system over the next couple days. Building seas up to 15
feet are expected through early in the workweek. Seas at the outer
buoy are reading 10 feet at around 12 seconds from the ESE.
Please note that high seas, high surf, and strong rip currents
will be life-threatening to those entering the water.

&&

.HYDROLOGY...

Based on the most recent guidance, the most likely time period for
the heaviest rainfall activity is Saturday into Sunday, while the
areas most likely to receive the highest rainfall accumulations are
portions of eastern and southern Puerto Rico, where there is a
potential for rainfall totals to reach 8 to 10 inches with
locally higher amounts to around 16 inches. Across south-central
Puerto Rico and the US Virgin Islands, Vieques, and Culebra the
potential exists for rainfall totals to reach 4 to 6 inches.
Elsewhere, expect rainfall totals to range between 2 and 4 inches.

Considerable flash and urban flooding impacts are possible across
eastern and southern Puerto Rico on Saturday afternoon and
Sunday. Across central and northwest Puerto Rico as well as the
US Virgin Islands, this rainfall may produce limited flash and
urban flooding impacts. Additionally, mudslides/rockfalls are
possible in areas of higher terrain. The threat of flooding will
continue into Monday-- mainly in Puerto Rico.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...Tropical Storm Warning for PRZ001>013.

Flood Watch through Monday afternoon for PRZ001>013.

VI...Tropical Storm Warning for VIZ001-002.

Flood Watch through Monday afternoon for VIZ001-002.

&&

$$

CAM/ICP/RC/GRS