AXNT20 KNHC 231207
Tropical Weather Discussion
NWS National Hurricane Center Miami FL
807 AM EDT Sun Sep 23 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 0600 UTC surface analysis and satellite imagery through
Tropical Storm Kirk centered near 9.1N 28.0W at 23/0900 UTC or
400 nm SSW of the Southernmost Cabo Verde Islands moving W at 16
kt. Estimated minimum central pressure is 1006 mb. Maximum
sustained wind speed is 35 kt with gusts to 45 kt. Some
strengthening is forecast during the next day or two.
Weakening is likely during the middle to latter part of the week.
Scattered moderate to strong convection is from 08N-12N between
25W-32W. See the latest NHC forecast/advisory under AWIPS/WMO
headers MIATCPAT2/WTNT32 KNHC for more details.
Tropical Depression Eleven centered near 14.5N 55.0W at 23/0900
UTC or 360 nm ENE of the Windward Islands moving NW at 5 kt.
Estimated minimum central pressure is 1009 mb. Maximum sustained
wind speed is 25 kt with gusts to 35 kt. A slow west-northwest to
northwest motion is expected until the system dissipates in a day
or so. Scattered moderate convection is noted from 12N-15N
between 52W-55W. See the latest NHC forecast/advisory under
AWIPS/WMO headers MIATCPAT1/WTNT31 KNHC for more details.
Satellite imagery indicates that a non-tropical low pressure
system currently located about 1000 miles west-southwest of the
Azores is producing gale-force winds with some associated showers
and thunderstorms. Conditions appear conducive for this system to
acquire some subtropical or tropical characteristics during the
next day or so while meandering over the central Atlantic Ocean,
and the low could become a subtropical or tropical cyclone before
it is overtaken and absorbed by a cold front late Tuesday or
Wednesday. The system has a high 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.
A cold front extends from a 1004 mb low pressure located N of the
area near 34N46W to 31N40W to 24N50W to 27N60W. The most recent
scatterometer data provide observations of minimal gale-force
winds N of 30N within 60 nm E of front with seas 11-13 ft. These
conditions are expected to decrease below gale shortly at 23/1200
A tropical wave has its axis along 46W 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 44W. Isolated moderate convection is located from 03N-14N
A Central American tropical wave has its axis along 89W from 08N-
20N, 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. Widely scattered
moderate convection is south of 20N between 85W-92W.
The monsoon trough extends from the African coast near 13N17W to
10N20W. It continues west of T.S. Kirk near 06N30W to 05N34W. The
ITCZ begins near 05N34W to 04N40W to 05N44W, then resumes near
05N48W to the South American coast near 04N51W. Aside from the
convection associated with the tropical wave and cyclones across
the area, widely scattered moderate convection is located S of 75
the monsoon from 04N-11N between 10W-18W.
GULF OF MEXICO...
An upper-level cyclonic circulation is centered near 25N87W. This
feature is enhancing convection across the eastern Gulf waters
mainly along 84W. To the west, a surface trough is analyzed along
91W from 24N-29N. Scattered showers are noted along the trough. A
cold front is entering the northwest Gulf enhancing convection
north of 25N and west of 95W. This front is likely to stall and
dissipate today. 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 this trough.
A tropical wave is moving across Central America, and a portion
of the wave's convection is over the W Caribbean. 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 13N and eastward to 78W. Plenty of
moisture will persist over the extreme southwest Caribbean, Panama
and Costa Rica through the weekend. Elsewhere, fresh to strong
winds prevail over the central Caribbean. These winds will
diminish across most of the basin by tonight.
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
A broad 1010 mb low is centered near 28N67W. A surface trough
runs through the low from 30N64W to the low center to 26N72W.
Scattered showers are noted along the trough and near the low.
Unfavorable upper-level winds and dry air are expected to limit
development today, but conditions could become more conducive for
some development of this system on Monday or Tuesday while it
moves westward and west-northwestward over the southwestern
Atlantic Ocean. By the middle of next week, strong upper-level
winds are likely to limit additional development as the system
turns northward and moves closer to the southeastern coast of the
United States. This feature has a low chance of tropical cyclone
formation during the next 48 hours.
The remainder of the basin is under the influence of a surface
ridge, anchored by a 1028 mb high centered near 40N21W.
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