[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 042352
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
752 PM EDT Thu Oct 4 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 1800 UTC surface analysis and satellite imagery through
2345 UTC.

...SPECIAL FEATURES...

Tropical Storm Leslie centered near 33.3N 57.5W at 04/2100 UTC
or 370 nm E of Bermuda moving N at 10 kt. Estimated minimum
central pressure is 982 mb. Maximum sustained wind speed is 60
kt with gusts to 75 kt. Scattered moderate convection extends
outward to 270 nm in the northwest quadrant and 210 nm in the
other quadrants. A northward motion with an increase in forward
speed is expected through tonight. A reduction in speed is
forecast on Friday and Friday night, with Leslie turning toward
the east-southeast over the weekend. Gradual weakening is
forecast to continue during the next several days. See the latest
NHC forecast/advisory under AWIPS/WMO headers MIATCPAT3/WTNT33
KNHC for more details.

...TROPICAL WAVES...

A far eastern Atlantic tropical wave extends its axis along 29W
from 03N-15N, moving westward at 10-15 kt. Scattered moderate
convection is noted within 270 nm of the wave axis from 04N-13N.
GOES-16 Total Precipitable Water imagery shows a moisture maximum
surrounding the wave. The wave has an associated 700 mb trough, as
depicted by model analyses.

A central Atlantic tropical wave is along 47W from 06N-15N moving
westward around 10 kt. Scattered showers are occurring along the
wave axis and extending to 180 nm east of the wave axis from 08N-
15N. The wave has an associated 700 mb trough, as shown by model
analyses.

An eastern Caribbean tropical wave has its axis along 68W from
09N-19N, moving westward around 10 kt. Scattered moderate
convection is observed in the vicinity of this wave enhanced by
upper level diffluence prevailing across the central Caribbean
west of the wave.

...MONSOON TROUGH/ITCZ...

The monsoon trough extends from the coast of Guinea-Bissau near
11N15W to 10N20W to 07N33W. The ITCZ extends from 07N33W to
08N45W, then continues west of a tropical wave from 08N48W to the
coast of northeast Venezuela near 09N61W. Aside from the
convection mentioned in the tropical waves section above, isolated
showers and thunderstorms are noted along and within 120 nm north
of the ITCZ between 51W-56W. Scattered moderate and isolated
strong convection is occurring along the west coast of Africa over
Guinea-Bissau and western Guinea. This scattered activity extends
offshore the west coast of Africa for 120 nm from 06N-12N.

...DISCUSSION...

GULF OF MEXICO...

Scattered showers are moving westward over the northern Gulf from
25N-30N between 87W-92W. This activity is being enhanced by an
area of upper-level diffluence over the Gulf stemming from an
upper-level ridge over the south-central U.S. GOES-16 TPW imagery
shows that the highest moisture in the area is near 90W-92W moving
westward. These showers and storms should diminish before
reaching 94W as they encounter increasingly pronounced low and mid
level ridging. A surface trough is analyzed over the central Bay
of Campeche. Scattered showers are noted west of the trough, just
offshore the coast of Mexico between Veracruz and Tampico.

Expect ridging to prevail over the forecast area through the
weekend. A surface trough will develop each evening over the
Yucatan Peninsula. The trough will move into the SW Gulf
overnight, where it will dissipate each morning. Moderate to fresh
winds will accompany the trough.

CARIBBEAN SEA...

A large cyclonic gyre, defined by a broad area of low pressure,
covers a portion of Central America and the western Caribbean Sea.
Within this gyre, a surface trough is analyzed from 20N80W to a
1007 mb low near 15N83W to 11N84W. Satellite imagery shows
scattered moderate to isolated strong convection across the
central Caribbean between 69W-80W. Some slow development of this
system is possible this weekend or early next week as the system
drifts northwestward across the northwestern Caribbean and the
southern Gulf of Mexico. A mid to upper level trough extending
over the Bahamas and Greater Antilles will help advect moisture
northwestward over the next several days. As a result, heavy
rainfall is likely to spread over portions of Hispaniola, Jamaica,
Cuba, the Yucatan Peninsula and Central America Friday through
early next week.

A tropical wave is over the eastern Caribbean. Refer to the
Tropical Waves section above for details. Large NNE swell
generated from Leslie will continue to pass through the Atlantic
passages into the Caribbean through the end of the week before
subsiding.

ATLANTIC OCEAN...

Two tropical waves are over the tropical Atlantic between the
west coast of Africa and the Lesser Antilles. See above for
details. Leslie is described in the Special Features section
above.

A weak surface trough located near the east coast of South
Florida is enhancing coverage of showers over the NW Bahamas and
the southern and central Florida peninsula. This activity should
continue through this evening as the trough moves westward.
Another surface trough is analyzed from 21N61W to 23N57W with
scattered showers. An E-W surface trough is analyzed to the east
of Leslie from 31N47W to 30N33W. Scattered showers and
thunderstorms are seen south of this trough from 25N-28N between
32W-40W. Enhanced moisture from the tropical wave along 47W is
streaming northeastward between an upper-level trough to the
northwest and an upper-level ridge to the southeast.

A high pressure ridge off the southeast coast of the U.S. is
leading to generally quiet weather in the area between Bermuda and
the Bahamas.

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

$$

ERA/AH
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