Caribbean - Central America Weather

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
534 AM AST WED JUL 27 2016

.SYNOPSIS...A generally stable air mass will prevail across the
forecast area today. Saharan Air Layer is still present over the
area...resulting in hazy skies and somewhat reduced visibilities.
Then...upper level trough/TUTT will retrogress across the
forecast area on Thursday...enhancing the development of showers
and thunderstorms across the region. The next tropical wave
expected on Sunday.

&&

.DISCUSSION...Fair weather will prevail across Puerto Rico and
the U.S. Virgin Islands today. Saharan Air Layer will persist
across the area over the next few days...resulting in hazy skies
and somewhat reduced visibilities. Although...relatively dry and
stable pattern will continue across the local islands over the
next 24 hours...diurnal induced showers and a thunderstorm or two
can not ruled out across Northwest Puerto Rico this afternoon.
Elsewhere...little or no shower activity is anticipated today.

Then...a upper trough/TUTT will move over the local region on
Thursday enhancing the shower and thunderstorm activity. Strong
thunderstorms may develop in the afternoon due to the influence
of the TUTT. At the same time...Saharan Dust will be presented
over the area...limiting the coverage of the showers and
thunderstorms. On Thursday...afternoon showers and thunderstorms
will focus mainly over the Central Interior...West and South
portions of Puerto Rico.

For Saturday...Drier and stable air mass is forecast ahead of the
next tropical wave. Moisture associated with the wave will likely
reach the local region on Sunday. This unstable environment will
support the development of scattered to numerous showers across
the regional waters and portions of the islands.

&&

.AVIATION...Mostly VFR conditions are expected to continue this
morning across the local flying area. Only VCSH due to ISOLD SHRA
expected over the Leewards, USVI and Eastern PR taf sites. East
winds will continue at around 10KT or less but increasing to 10-15
knots after 27/13Z with sea breeze variations. VCSH/VCTS likely at
TJBQ and TJMZ after 27/17Z with TSRA possible at TJMZ after 27/19Z.
Saharan dust will reduce visibilities across some of the local taf
sites during the next 24 hours.

&&

.MARINE...Winds of 10-20 knots and seas of 3-5 feet are expected
across the local waters over the next several days. Small craft
operators should exercise caution across the coastal waters of
Puerto Rico this afternoon due to winds around 20 knots. There is
a moderate risk of rip currents mainly across northern Puerto Rico
and some coastal areas of southeastern Puerto Rico including Culebra
and Vieques.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 81 90 80 / 30 40 40 30
STT 90 80 90 79 / 30 40 40 30

[cycloneye]

Let's watch this wave in the next few days.

TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
800 AM EDT WED JUL 27 2016

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

1. A tropical wave located along the coast of western Africa is
producing a large area of cloudiness and disorganized shower
activity. Environmental conditions are expected to be conducive
for some development of this disturbance during the next several
days while it moves generally westward at 15 to 20 mph.
* Formation chance through 48 hours...low...10 percent
* Formation chance through 5 days...low...20 percent

Forecaster Stewart

[Gustywind]

Here is a good link to monitor 96L trek.

http://www.ssd.noaa.gov/PS/TROP/floater ... oater.html

[Gustywind]

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
600 AM EDT WED JUL 27 2016


A tropical wave came off the Western coast of Africa earlier this
morning. The wave extends from 07N-20N with axis near 18W,
expected to move at 10 kt within the next 24 hours. Heavy showers
and isolated tstms associated with the wave are from 05N-20N E of
21W.

[cycloneye]

 https://twitter.com/wunderground/status/758339415559114753

[cycloneye]

2 PM TWO up to 30%-40%.

TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
200 PM EDT WED JUL 27 2016

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

A tropical wave accompanied by a broad low pressure system is
producing a large area of cloudiness and disorganized shower
activity about 550 miles southeast of the Cabo Verde Islands.
Environmental conditions are expected to be conducive for gradual
development of this disturbance during the next several days while
the system moves generally westward at 15 to 20 mph.
* Formation chance through 48 hours...low...30 percent
* Formation chance through 5 days...medium...40 percent

$$
Forecaster Stewart

[Gustywind]

Tropical Weather Discussion...correction for satellite time
NWS National Hurricane Center Miami FL
205 PM EDT WED JUL 27 2016

Tropical wave in the far east Tropical Atlantic extends along
15W/16W from 7N to inland over Africa moving west 10 to 15 kt
over the past 6 hours. The wave was relocated based on latest
scatterometer pass at 27/1120 UTC. Wave coincides with a 700 mb
trough south of 12N as depicted in the global models and is
embedded within broad area of moisture as seen on the SSMI Total
Precipitable Water imagery. Clusters of scattered moderate
convection are from 5N-10N between 11W-20W and from 14N-17N
between 27W-29W.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
204 PM AST WED JUL 27 2016

.SYNOPSIS...Saharan dust is creating hazy skies across the forecast
area. A TUTT to the northeast of the islands will move westward
and across the forecast area on Thursday. The next tropical wave
is expected to enter the eastern Caribbean on Sunday.

&&

.DISCUSSION...Hazy skies prevailed across the islands Today. This
limited the shower development across much of the forecast area.
However, locally induced showers and two isolated thunderstorms
developed during the last few hours. One briefly developed across
the Toa Baja/Dorado area and the doppler radar estimated between
1-2 inches. The other one developed over western PR, with intense
cloud to ground lightning observed across Mayaguez and Anasco.
Urban and small stream flooding is likely with this activity
during the next hour or so. Fair weather conditions are expected
overnight into early Thursday morning. However, during the
afternoon hours, TUTT will enhance showers and thunderstorms
across the mountain ranges of PR. This will result in periods of
heavy rainfall, gusty winds and cloud to ground lightning. Flash
flooding can`t be ruled out due to saturated soils across western
PR.

During the weekend, a somewhat drier air mass is expected on
Saturday ahead of the next tropical wave. However, showers and
isolated thunderstorms can`t be ruled out during the afternoon
hours. Moisture increases with the passage of the topical wave on
Sunday through Monday. This unstable environment will once again
enhance the development of scattered to numerous showers across
the regional waters and portions of the islands.


&&

.AVIATION...Mostly VFR conditions with a Saharan air mass,
which could reduce visibilities at the local islands are expected
during the next 24 hours. However, VCSH/ISOLD TSRA are likely at
TJBQ/TJMZ this afternoon thru 21z. Then aft 23z a few VCSH and
brief SHRA are possible over the Leewards, USVI and Eastern PR taf
sites. E-ESE winds will prevail at 10-15 KT. Winds are expected
to diminish at 10 knots or less overnight.


&&

.MARINE...Seas between 3-5 feet are expected through at least
Friday. Increasing between 4-6 feet during the weekend as a
tropical wave. Winds will continue mainly from the east between
10-20 knots.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 81 90 80 89 / 40 40 30 30
STT 80 90 79 89 / 40 40 30 30

[Gustywind]

First African Tropical Wave of the Year to Achieve 'Invest' Designation: 96L

By: Jeff Masters , 15:21 GMT le 27 juillet 2016
https://www.wunderground.com/blog/JeffM ... rynum=3366


One of the strongest tropical waves of the 2016 African monsoon season moved off the coast of Africa on Wednesday morning, and has the potential to develop into a tropical depression in the coming days as it tracks westwards at 15 - 20 mph into the middle Atlantic. NHC designated this disturbance Invest 96L on Wednesday morning--the first "Invest" of the year for an African tropical wave, and something we'll see a lot more of as once the Atlantic hurricane season hits high gear during the mid-August through late September peak of the season. Satellite loops on Wednesday morning showed 96L had only a limited amount of heavy thunderstorms, which were poorly organized and had no signs of a surface circulation. Wind shear was moderate, near 10 - 20 knots, and sea surface temperatures (SSTs) were warm, near 28°C (82°F), which was about 1°C (1.8°F) above average.

Forecast for 96L
Steering currents favor a westerly motion for 96L, with the system slowing down in forward speed late this week and reaching a point near 40°W, midway between the Lesser Antilles Islands and Africa, on Monday. The 8 am EDT Wednesday run of the SHIPS model predicted modestly favorable conditions for development through Friday, with wind shear in the moderate range, 10 - 20 knots, and warm SSTs near 28°C. However, on Saturday and Sunday, 96L will encounter cooler waters, with temperatures a marginal 26°C. The SHIPS model also predicts that wind shear over the weekend will rise to the high range, above 20 knots, and the atmosphere will get very dry, due to an intrusion of the Saharan Air Layer (check out this animation of the 10-day African dust forecast from NASA.) These unfavorable conditions would stymie any development of 96L, but forecasts of dry air and wind shear this far into the future are unreliable.

The Wednesday morning operational runs of our three reliable models for predicting tropical cyclone genesis, the European, GFS and UKMET models, all supported some limited development of 96L, but stopped short of predicting it would become a tropical depression. The 00Z Wednesday run of the GFS ensemble forecast, done by taking the operational high-resolution version of the model and running it at lower resolution with slight perturbations to the initial conditions in order to generate a range of possible outcomes, had about 40% of its twenty ensemble members predict that a tropical depression would form this weekend or early next week midway between Africa and the Lesser Antilles. Most of these forecasts had the storm dying out the middle Atlantic, due to unfavorable conditions, and none had it becoming a hurricane. Less than 10% of the 50 members of the 00Z Wednesday European ensemble model forecasts showed a tropical depression forming in the Atlantic over the next ten days. In their 8 am EDT Wednesday Tropical Weather Outlook, NHC gave 96L 2-day and 5-day development odds of 10% and 20%, respectively. Though the long-range uncertainty on what 96L might do is high, one reasonable scenario is for the system to steadily grow in organization the next few days, come close to or achieve tropical depression status by Saturday, then get ripped apart by wind shear and dry air well before reaching the Lesser Antilles Islands by the middle of next week. Should 96L overachieve, the next name on the Atlantic list of named storms is Earl.

[cycloneye]

TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
800 PM EDT WED JUL 27 2016

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

1. A tropical wave accompanied by a broad low pressure system is
producing a large area of cloudiness and disorganized shower
activity about 550 miles southeast of the Cabo Verde Islands. Some
development of this system is possible during the next few days
while it moves westward or west-northwestward at about 15 mph.
However, environmental conditions are expected to become less
conducive for development early next week while the system is over
the central tropical Atlantic Ocean.

* Formation chanc through 48 hours...low...30 percent
* Formation chance through 5 days...medium...40 percent

Forecaster Berg

]

[Gustywind]

000
AXNT20 KNHC 271741 CCA
TWDAT

Tropical wave in the far east Tropical Atlantic extends along
15W/16W from 7N to inland over Africa moving west 10 to 15 kt
over the past 6 hours. The wave was relocated based on latest
scatterometer pass at 27/1120 UTC. Wave coincides with a 700 mb
trough south of 12N as depicted in the global models and is
embedded within broad area of moisture as seen on the SSMI Total
Precipitable Water imagery. Clusters of scattered moderate
convection are from 5N-10N between 11W-20W and from 14N-17N
between 27W-29W.

[cycloneye]

SYNOPSIS...A surface high pressure will continue to dominates
the local region through Saturday night. An upper level trough
will move across the area today. An active tropical wave will
affect the local area Sunday and Monday. Saharan Air Layer will
encompass the region after the wave.

&&

.DISCUSSION...Passing showers were seen across the coastal waters
overnight. Some of these showers affected the local islands...but
rainfall accumulation were minimal. This increase in moisture is
associated with an approaching upper level trough which is located
northeast of the U.S. Virgin Islands. Although this trough is not
strong enough...will aid in the development of showers and
thunderstorms mainly over the western interior and west section of
Puerto Rico.

An active tropical wave...currently located in the central
Atlantic it is expected to approach the local area by Sunday. At
this time...models agreed on the timing of the wave but disagree
somewhat on the strength of the wave. The ECMWF model forecast a
stronger wave affecting the local area...compared to the GFS. The
most important thing it is that both models agreed on active
weather beginning on Sunday morning and continuing through Monday
morning. We will continue to closely monitor the evolution of this
wave next few days. Stay tuned.

&&

.AVIATION...Mostly VFR conditions with a Saharan air layer could
slightly reduce VIS at the local terminals but still expected to be
P6SM during the next 24 hours. For this morning, VCSH and brief SHRA
possible over the Leewards, USVI and TJSJ TAF sites. Easterly winds
to increase to around 10-15 KT and gusty after 28/13Z prevailing
from the E with sea breeze variations. SHRA/TSRA expected to develop
over PR after 28/16Z with mountain obscurations. VCTS/TSRA likely to
affect areas in and around TJPS and TJMZ, VCSH/SHRA at TJBQ.

&&

.MARINE...Tranquil marine conditions are expected to continue
through at least Saturday. Seas up to 4 feet and winds up to 15
knots are expected.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 91 79 89 80 / 20 30 30 20
STT 90 79 89 81 / 40 30 30 20

[cycloneye]

TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
800 AM EDT THU JUL 28 2016

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

A tropical wave accompanied by a low pressure system is producing an
area of showers and thunderstorms about 400 miles southeast of the
Cabo Verde Islands. Some development of this disturbance is
possible during the next few days while it moves westward or
west-northwestward at 10 to 15 mph. However, environmental
conditions are expected to become less conducive for development
early next week when the system is over the central tropical
Atlantic Ocean.
* Formation chance through 48 hours...low...30 percent
* Formation chance through 5 days...medium...40 percent

$$
Forecaster Stewart

[cycloneye]

We have new Invest 97L east of the islands and we have to watch it very closely.The models move it thru the Lesser Antilles by Saturday.

TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
200 PM EDT THU JUL 28 2016

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

1. A tropical wave located about 1700 miles east-southeast of the
Leeward Islands is moving westward at about 30 mph. Environmental
conditions are expected to be somewhat conducive for development
this weekend when the disturbance could be near the northern Lesser
Antilles and Puerto Rico.
* Formation chance through 48 hours...low...20 percent
* Formation chance through 5 days...low...30 percent

2. A tropical wave accompanied by a low pressure system is producing an
area of showers and thunderstorms about 350 miles south-southeast of
Cabo Verde. Some development of this disturbance is possible during
the next few days while it moves westward or west-northwestward at
10 to 15 mph. However, environmental conditions are expected to
become less conducive for development early next week when the
system is over the central tropical Atlantic Ocean.
* Formation chance through 48 hours...low...30 percent
* Formation chance through 5 days...medium...40 percent

Forecaster Stewart

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
211 PM AST THU JUL 28 2016

.SYNOPSIS...
A dry air mass with Saharan Dust Particles moved across the local
islands today. A weak tropical wave is expected to pass by the
region on Friday. Model guidance forecast the arrival of a strong
tropical wave by Sunday afternoon and into Monday. At the
surface, a broad surface high pressure across the northeast
Atlantic will continue to produce a moderate east wind flow across
the region for the next several days. At upper levels, a TUTT low
will move over the region today and Friday.

&&

.DISCUSSION...
Fair weather conditions with Saharan Dust Particles and hot
temperatures prevailed during most of the morning hours and into
the afternoon. However, showers and thunderstorms are expected
over the interior and western sections of Puerto Rico mainly due
to the proximity of a TUTT low and it interaction with the diurnal
heating and local effects. Some of this activity could produce
gusty winds, frequent lightning, small hail and urban and small
stream flooding.

A weak tropical wave is forecast to arrive by Friday. As a result,
another round of showers and thunderstorm could be expected for
tomorrow afternoon. Fair weather conditions should prevailed on
Saturday as a dry air mass is forecast to move over the islands.

A strong tropical wave is forecast to reach the CWA Sunday
afternoon and Monday. If the models are correct, this will
significantly enhance the development of showers, thunderstorms
and flooding across the islands. Please stay tuned and monitor
the evolution of this system.

&&

.AVIATION...
Mostly VFR cond thru the rest of the forecast period. SHRA/TSRA
with mtn obscuration expected across interior and western
portions of PR from 16Z-22Z, possibly affecting TJMZ and TJBQ.
SHRA/VCTS possible for TJSJ and TJPS. Low level winds mainly from
the east at 10-15 kts with higher gusts and sea breeze variations.

&&

.MARINE...
Tranquil marine weather conditions are expected during the rest
of today, however rough seas and gusty winds can be expected in
and around showers and thunderstorms. Mariners should monitor the
evolution of a strong tropical wave, which is forecast to move
across the region Sunday and Monday.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 79 89 80 90 / 30 30 20 20
STT 79 89 81 92 / 30 30 20 20

[cycloneye]

TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
800 PM EDT THU JUL 28 2016

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

A tropical wave located over the Atlantic halfway between the west
coast of Africa and the Lesser Antilles is moving rapidly westward.
Given the fast motion of the system, development, if any, will be
slow to occur. However, this system will likely bring showers and
gusty winds to portions of the Leeward Islands during the weekend,
and then, the activity should spread westward across the Caribbean
Sea.
* Formation chance through 48 hours...low...20 percent
* Formation chance through 5 days...low...30 percent

The area of disturbed weather associated with a tropical wave and a
low pressure system centered about 350 miles south-southeast of
the Cabo Verde Islands has changed little in organization during the
day. This system has some potential for slight development during
the next day or two, before the disturbance encounters a less
favorable environment over the central tropical Atlantic next week.
* Formation chance through 48 hours...low...30 percent
* Formation chance through 5 days...medium...40 percent

$$
Forecaster Avila

[Gustywind]

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
741 PM EDT THU JUL 28 2016


96L:
A tropical wave is in the far east Tropical Atlantic with axis
that extends from 17N20W to a 1010 mb low near 11N21W. These
features are moving west at about 10 kt over the past 24 hours.
The wave coincides with a 700 mb trough as depicted in the global
models and is embedded within broad area of moisture as seen on
the SSMI Total Precipitable Water imagery. Scattered moderate
convection is from 7N-14N between 20W-24W.

97L:
A tropical wave is moving over the central Tropical Atlantic with
axis from 18N38W to 10N38W, moving west at about 15 kt over the
past 24 hours. A 700 mb trough is depicted by the models between
38W-42W and a surge moisture prevails in the wave's environment as
depicted by SSMI Total Precipitable Water imagery. Isolated
convection is observed across the southern portion of the wave
south of 15N between 37W- 41W.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
550 AM AST FRI JUL 29 2016

.SYNOPSIS...Upper level trough will aid in the development of
showers and thunderstorms today. A strong Tropical wave located in
the central Atlantic is expected to move across the region
Saturday night into Sunday. Saharan Air Layer is expected to
affect the region after the passage of the wave.

&&

.DISCUSSION...Scattered showers were seen across the coastal
waters overnight. Some of these showers affected the eastern half
of Puerto Rico and the U.S. Virgin Islands. Some showers produced
heavy rainfall in localized areas. This activity is associated
with an upper level trough which will be passing across the area
today. This upper level trough will aid in the development of
showers and thunderstorms mainly over the western interior and
west sections of Puerto Rico. After the passage of this
feature...drier air will move across the region Saturday.

Our attention is focus on a strong tropical wave which is located
near 45 west longitude this morning. This wave is accompany by
very deep tropical moisture. Global models agreed on bringing this
system to the local area Sunday. However...the leading edge of
this system is expected to affect the local region as early as
Saturday afternoon. At this time...looks like the most active
weather will occur Sunday morning into the afternoon...with the
GFS model showing impressive precipitable water values over the
area as high as 2.5 inches. Regardless if the system develops into
a tropical cyclone or not...the potential for very heavy rainfall
and strong gusty are highly possible mainly Sunday afternoon as
the wave moves across the region. In fact...flash flooding can`t
be ruled out as a very moist southeasterly winds are expected to
aid in the development of showers and thunderstorms across the
area. We will continue to closely monitor the progress of this
system. Stay tuned.

&&

.AVIATION...ISO-SCT SHRA will continue to produce brief periods of
MVFR CIGS across the Leeward, USVI and Eastern PR taf sites this
morning. LLVL winds will shift from ENE to E after 29/12z. After
29/17Z areas of SHRA/TSRA will form across Western and Northwest PR
with mountain obscurations and periods of MVFR CIGS/VSBYS from
29/18Z to 29/22Z. After 29/18Z SHRA and possible TSRA will also move
from the east into TNCM and TKPK with MVFR likely before 30/00Z.

&&

.MARINE...Due to the proximity of the aformentioned Tropical
Wave..hazardous seas are expected from Saturday afternoon through
at least Sunday afternoon. Therefore...a Small Craft Advisory has
been issued for the offshore Atlantic waters and the Anegada
Passage due to increasing seas up to 8 feet.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 79 89 79 / 30 20 20 60
STT 89 80 92 79 / 30 20 20 60

[cycloneye]

TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
800 AM EDT FRI JUL 29 2016

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

A tropical wave located about 1200 miles east of the Lesser
Antilles is moving westward at about 25 mph. The associated shower
activity is poorly organized, and given the fast motion of the
system any development should be slow to occur. However, this system
will likely bring showers and gusty winds to portions of the Leeward
Islands and the eastern Caribbean Sea during the weekend.
* Formation chance through 48 hours...low...20 percent
* Formation chance through 5 days...low...30 percent

Shower activity associated with a tropical wave and a low pressure
system centered a couple of hundred miles south of the Cabo Verde
Islands has become better organized since yesterday. Some
additional development is possible during the next day or two before
the disturbance encounters a less favorable environment over the
central tropical Atlantic next week.
* Formation chance through 48 hours...medium...40 percent
* Formation chance through 5 days...medium...50 percent

$$
Forecaster Beven

[cycloneye]

 https://twitter.com/JimCantore/status/759031427329646592