[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 032354
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
754 PM EDT Wed Oct 3 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...

Hurricane Leslie centered near 29.9N 56.9W at 03/2100 UTC or 430
nm ESE of Bermuda moving N at 3 kt. Estimated minimum central
pressure is 975 mb. Maximum sustained wind speed is 70 kt with
gusts to 85 kt. Scattered to numerous moderate convection is
noted within 120 nm of the center. Little motion is expected for
the next several hours. A northward motion is forecast to begin
this evening, and this motion with an increase in forward speed
should continue through Friday night. A turn to the east is
expected this weekend. Some additional strengthening is forecast
during the next day or so, but a slow weakening trend is expected
to begin on Friday. 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 23W
from 03N-15N, moving westward around 10-15 kt. Scattered moderate
convection is within 90 nm on either side of the wave's axis.
Total Precipitable Water imagery shows deep moisture surrounding
the wave. The wave has an associated 700 mb trough, as shown by
model analyses.

A central Atlantic tropical wave is along 41W from 05N-14N moving
westward around 10-15 kt. Scattered showers and thunderstorms are
occurring along and west of the wave's axis between 41-48W. The
wave has an associated 700 mb trough, as shown by model analyses.

An eastern Caribbean tropical wave has its axis along 64W from
06N-18N, moving westward at 10-15 kt. A TPW animation shows a
slight moisture maximum associated with the wave. The wave is not
producing any significant convection due to an area of mid-level
ridging and sinking air that prevails across the eastern
Caribbean.

...MONSOON TROUGH/ITCZ...

The monsoon trough extends from the coast of west Africa near the
Senegal/Mauritania border near 16N16W to 09N20W to 07N25W to
09N40W. The ITCZ extends from 09N41W to 08N59W. Aside from the
convection mentioned in the tropical waves section above,
isolated showers are observed within 240 nm north of the ITCZ
between 48W-53W.

...DISCUSSION...

GULF OF MEXICO...

A surface trough is moving slowly westward over the northern Gulf,
and is analyzed along 87W between 26N-28N. Scattered showers are
occurring within 60 nm of the trough axis. Enhanced moisture
associated with this trough is seen on GOES-16 TPW imagery.
Enhanced convection will continue through today offshore the
northern Gulf coast in association with this trough. Scattered
showers are over the Bay of Campeche south of 21N and west of
94W. Surface ridging prevails across the northwest Gulf. Little to
no shower activity is observed north of 24N and west of 90W.

Expect ridging to prevail over the forecast area during the next
few days. 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 tropical wave is over the eastern Caribbean. Refer to the
Tropical Waves section above for details. A broad surface trough
is over the western Caribbean, analyzed from 18N78W to a 1007 mb
low near 16N80W to 12N83W. This position is supported by a recent
ASCAT pass. Satellite imagery shows scattered moderate convection
prevailing across the western Caribbean mainly west of 75W. Some
slow development of this system is possible this weekend while the
low drifts across the northwestern Caribbean Sea. A mid to upper
level trough extending over the Bahamas and Greater Antilles will
help advect moisture northward as the week progresses. As a
result, very heavy rainfall is likely to spread over sections of
Hispaniola and Jamaica later this week and into the weekend.

Another area of convection that was generated yesterday closer to
the aforementioned trough axis has been drifting eastward and is
gradually weakening as it moves farther from the trough. This area
of scattered moderate convection is located from 13N-15N between
69W-72W. Upper-level diffluence in this area is becoming less
pronounced, so expect the convection in this area to become less
intense over the next 12 hours.

Large NNE swells generated from Leslie will continue to move
through the Atlantic passages into the Caribbean during the next
few days.

ATLANTIC OCEAN...

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

An area of upper-level diffluence just east of the central Bahamas
is causing scattered showers and thunderstorms from 25N-27N
between 71W-75W. This activity could continue in this area over
toward the central Bahamas through this evening.

An E-W surface trough is analyzed to the east of Hurricane Leslie along
31N between 36W-42W. Scattered moderate convection is seen along
and south of this trough to 29N. Another surface trough is
analyzed south of Hurricane Leslie from 25N56W to 20N67W.
Scattered showers are occurring along this trough. GOES-16 Total
Tropical moisture from the vicinity of 17N61W is being
transported northeastward to the vicinity of the surface trough
near 30N36W. The moisture is following the mid to upper level flow
in between the cyclonic flow associated with Leslie and
anticyclonic flow in the vicinity of 23N43W.

Surface ridging generally prevails over the eastern Atlantic,
leading to quiet weather from 19N-27N east of 40W.

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

$$

AG/ERA
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