[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 221753
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
153 PM EDT Sat Sep 22 2018

Tropical Weather Discussion for North America, Central America
Gulf of Mexico, Caribbean Sea, northern sections of South
America, and Atlantic Ocean to the African coast from the
Equator to 32N. The following information is based on satellite
imagery, weather observations, radar and meteorological analysis.

Based on 1200 UTC surface analysis and satellite imagery through
1715 UTC.

...Special Features...

The area of low pressure south of the Cabo Verde Islands has
organized into Tropical Storm Kirk. This storm is centered near
8.3N 23.6W at 22/1500 UTC, or 390 nm (730 km) S of the
southernmost Cabo Verde Islands, moving W at 12 kt. A westward to
west-northwestward motion at a similar forward speed is expected
to continue through tonight. A faster westward motion across the
deep tropical Atlantic Ocean is expected Sunday through Tuesday.
Minimum central pressure is 1005 mb. Maximum sustained wind speed
is 35 kt with gusts to 45 kt. Some strengthening is forecast
through Sunday, with little change in intensity forecast on Monday
and Tuesday. Scattered moderate convection is observed within 150
nm of the center in the western semicircle, especially the NW
quadrant. Scattered moderate convection is also noted within 270
nm of the center in the eastern semicircle. See the latest NHC
forecast/advisory under AWIPS/WMO headers MIATCMAT2/WTNT22 KNHC
for more details.

Tropical Depression Eleven is centered near 13.2N 53.8W at
22/1500 UTC, or 420 nm (780 km) E of the Windward Islands, moving
W at 3 kt. A westward to west-northwestward motion at a slightly
faster forward speed is expected during the next couple of days.
Estimated minimum central pressure is 1008 mb. Maximum sustained
wind speed is 25 kt with gusts to 35 kt. Little change in strength
is forecast during the next day or two, and the depression is
forecast to become a remnant low on Sunday and dissipate east of
the Lesser Antilles Sunday night. Scattered moderate convection
is noted between 90 nm-240 nm from the center in the E semicircle.
See the latest NHC forecast/advisory under AWIPS/WMO headers
MIATCMAT1/WTNT21 KNHC for more details.

Satellite imagery indicates that a frontal non-tropical low
pressure system is located about 870 nm west-southwest of the
Azores. Conditions are expected to become conducive for this low
to acquire subtropical or tropical characteristics during the next
day or so, and a subtropical or tropical cyclone is likely to
form by early next week while the low meanders over the central
Atlantic Ocean. The system has a medium chance of tropical
cyclone formation within the next 48 hours. Please refer to the
latest Tropical Weather Outlook under AWIPS/WMO headers
MIATWOAT/ABNT20 KNHC for more information.

...TROPICAL WAVES...

A tropical wave has its axis along 40W/41W from 03N-16N and is
moving west at 10-15 kt. The wave corresponds nicely with a
maximum in TPW imagery. Model analyses depict an associated 700 mb
trough along 41W. Scattered showers and isolated thunderstorms
are located near and east of the wave axis from 09N-14N between
36W-41W. Scattered moderate convection is also noted from 07N-11N
between 42W-46W.

A western Caribbean Sea tropical wave has its axis along 84W from
08N-21N, moving west around 10 kt. The 700 mb trough associated
with this wave is well depicted in model guidance, and TPW
imagery shows abundant moisture in its environment. Scattered
moderate and isolated strong convection is noted from 12N-18N
between 82W-86W, including eastern Nicaragua and northeast
Honduras. Puerto Cabezas, Nicaragua is currently reporting
thunderstorms. Moisture associated with this wave will continue to
spread inland across Central America through tonight, likely containing
scattered showers and tstms.

...MONSOON TROUGH/ITCZ...

The monsoon trough extends from the African coast near the
Mauritania/Senegal border to 15N19W. It continues from 07N24W to
06N30W to 08N38W. The ITCZ begins near 09N43W and continues to
09N52W. Aside from the convection associated with the tropical
wave and cyclones across the area, scattered showers are located
along and within 90 nm south of the monsoon trough between 26W-
31W.

...DISCUSSION...

GULF OF MEXICO...

An upper-level cyclonic circulation is centered near 27N86W. A
surface trough is analyzed over the SE Gulf along 84W from 23N-
26N. Both features are helping to enhance convection slightly
across the eastern Gulf east of 86W from 23N-29N, where scattered
showers and isolated thunderstorms are observed. A surface trough
extending from the coast of SE Louisiana to 25N91W is producing
isolated showers and thunderstorms from 24N-26N between 88W-92W.
A cold front currently over east-central Texas is expected to move
eastward, reaching the Texas coast tonight. This front is likely
to just barely reach the NW Gulf off the Texas coast tonight
before stalling and dissipating on Sunday. A surface trough
located ahead of the front is currently just inland over south
Texas. Scattered moderate convection is noted over the NW Gulf
north of 27N and west of 92W. Gentle to moderate E to SE winds and
seas 3 ft or less will prevail across most of the Gulf of Mexico
through the middle of next week. A surface trough will develop
over the Yucatan peninsula each evening, shift W over the SW Gulf
each night, then dissipate by morning. Moderate to fresh winds
will accompany the trough.

CARIBBEAN SEA...

A tropical wave is moving across the far western Caribbean, and a
portion of this wave is entering Central America. Please see the
Tropical Waves section for more details.

The eastern Pacific monsoon trough combined with diffluence aloft
continues to enhance convection over portions of Panama and the
waters of the southwest Caribbean from the coasts of Panama and
Costa Rica northward to 12N and eastward to 78W. Plenty of
moisture will persist over the extreme southwest Caribbean, Panama
and Costa Rica through tonight. Elsewhere, fresh to strong winds
prevail over the central Caribbean. These winds will diminish
across most of the basin by Sun night.

ATLANTIC OCEAN...

Currently, there are two tropical cyclones and a tropical wave
between the west coast of Africa and the Lesser Antilles. Please
see the Special Features and Tropical Waves sections for more
details.

A broad 1011 mb low is centered 175 nm south of Bermuda. A
surface trough runs through the low from 30N61W to the low near
29N65W to 28N70W. Scattered moderate convection is seen extending
out to 180 nm from the center of the low in the eastern
semicircle. Strong upper-level winds and dry air are expected to
limit development for the next day or so, but conditions could
become more conducive for some development of this system by
early next week while it moves westward and west-northwestward
over the southwestern Atlantic Ocean. By the middle of next week,
upper-level winds are likely to increase again, which would limit
additional development as the system turns northward and moves
closer to the southeastern coast of the United States. The low
has a low chance of tropical cyclone formation during the next 48
hours.

A cold front extends from the low north of the area mentioned in
the Special Features section and enters the area near 31N45W and
extends to 28N50W to 29N57W. A stationary front then continues
from 29N57W to 31N60W. Scattered moderate convection is located
along the front and extending to 120 nm ahead of the front between
41W-50W. Recent scatterometer data shows winds are near gale force
just ahead of the front in the southwesterly flow from 27N-31N
between 42W-47W.

For additional information please visit
http://www.hurricanes.gov/marine

$$
HAGEN/GR
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