[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 022349
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
749 PM EDT Tue Oct 2 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 30.1N 56.4W at 02/2100 UTC
or 450 nm ESE of Bermuda moving SSW at 8 kt. Estimated minimum
central pressure is 986 mb. Maximum sustained wind speed is 60
kt with gusts to 75 kt. Latest ASCAT pass depicts tropical storm
force winds north of 28N between 54W-59W. Scattered moderate
convection is within 150 nm of the center, with the strongest
convection in the northwest semicircle. A slow south-
southwestward or southward motion is expected through Wed. A turn
to the north/northeast is forecast to occur through the rest of
the week. See the latest NHC forecast/advisory under AWIPS/WMO
headers MIATCPAT3/WTNT33 KNHC for more details.

...TROPICAL WAVES...

A far eastern Atlantic tropical wave was added to the analysis
just off the coast of Africa along 18W from 03N-16N, moving
westward 10-15 kt. Scattered moderate convection is occurring
within 180 nm west and 210 nm east of the wave axis. The wave
coincides with a maximum in total column water vapor as depicted
in the GOES-16 TPW product. The wave has a 700 mb trough
associated with it, as shown by model analyses.

A tropical wave is just east of the Lesser Antilles along 60W and
extends from Guyana to 18N, moving westward at 10 kt. A well-
defined 700 mb trough is shown in model analyses just east of
where the wave is analyzed. The wave has a well defined 700 mb
trough associated with it but lacks significant convection. A TPW
animation shows a moisture maximum is associated with this
tropical wave. Only a small area of isolated showers is seen east
of the wave axis from 09N-12N between 55W-58W. Otherwise, no
significant convection is noted.

...MONSOON TROUGH/ITCZ...

The monsoon trough extends from the coast of Senegal near 12N17W
to 09N23W to 09N36W. The ITCZ extends from 09N37W to 10N48W.
Aside from the convection mentioned in the tropical waves section
above, scattered showers are observed within 60 nm north and 120
nm south of the ITCZ between 35W-55W.

...DISCUSSION...

GULF OF MEXICO...

A weak surface trough is analyzed over the northeastern Gulf
along 87W from 25N-29N. The trough is producing scattered showers
and thunderstorms from 28N-29N east of 87W. This trough, along
with increasing moisture in the northeastern Gulf, could help to
enhance showers and thunderstorms over the northeast and north-
central Gulf tonight.

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 broad surface trough along 80W is associated with a broad area
of low pressure located over the southwestern Caribbean Sea.
Satellite imagery shows numerous moderate with embedded scattered
strong convection east of the trough from 12N-17N and between 72W
and 77W. Elsewhere east of the surface trough, scattered moderate
convection is present from 11N-18N between 71W and 78W. Two small
areas of scattered moderate convection are occurring just offshore
northeast Honduras and also just offshore east- central
Nicaragua. The persistent strong convection east of the trough is
being enhanced by an area of upper-level diffluence over the same
area. Some gradual development of the broad low pressure area is
possible late this week and this weekend while the low drifts
generally in a northward direction. A deepening mid to upper level
trough oriented E-W over the northern Caribbean and Greater
Antilles will help advect moisture northward as the week
progresses. As a result, heavy rain is likely to spread over
sections of Hispaniola and Jamaica later this week and into the
weekend.

Scattered showers and thunderstorms are occurring from 19N-21N
between 80W and 85W. Expect the activity in this area to remain
scattered and not very strong since upper-level troughing in the
area is weakening. Broad mid-level ridging is over the east-
central Caribbean with associated westerly upper level flow
leading to generally quiet weather conditions east of 71W.

Large NNE swell generated from Leslie will pass through the Atlantic
passages into the Caribbean.

ATLANTIC OCEAN...

The two tropical waves over the tropical Atlantic between Africa
and the Lesser Antilles are described in the Tropical Waves
section above. Tropical Storm Leslie is described in the Special
Features section above.

A broad mid to upper level trough over Leslie combined with an
area of upper-level diffluence to the southeast of Leslie
continues to enhance convection to the southeast of Leslie.
Scattered moderate convection is observed from 24N-29N between
42W-49W. A surface trough is analyzed extending from 28N54W to
20N63W. East of the trough axis, an area of scattered moderate
convection is noted from 20N-24N between 51W and 56W. Elsewhere
from 20N-26N, between 50W and the trough axis, scattered showers
and isolated thunderstorms are present. A shear line has developed
since this morning oriented east to west from 22N65W to 25N78W.
Scattered showers and thunderstorms are occurring within 60 nm of
the shear line. ASCAT and surface observations show NE 20-25 kt
winds along and north of the shear line.

The northeastern portion of the forecast area is under the
influence of a ridge, anchored by a 1018 mb surface high near
26N36W. Generally quiet weather prevails north of 20N and east of
40W.

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

$$

AG/ERA
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