Atlantic Tropical Weather Discussion (Text)

AXNT20 KNHC 211034

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
533 AM EST Tue Nov 21 2017

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 
0945 UTC.

Cyclogenesis is expected to occur late Wednesday into Wednesday
night across portions of the Gulf of Mexico producing near gale to
gale force northerly winds S of 22N W of 93W. The gale force wind
field is expected to persist through late Wednesday night... 
diminishing into strong to near gale force strength by Thursday 
morning across portions of the SW Gulf of Mexico. See the latest 
NWS High Seas Forecast under AWIPS/WMO headers MIAHSFAT2/FZNT02 
KNHC for more details.

The monsoon trough extends from the African coast near 11N16W to 
09N19W. The Intertropical Convergence Zone axis extends from 
09N19W to 08N33W to 06N42W to 05N52W. Scattered moderate 
convection is from 02N-11N between 08W-37W.


A middle to upper level trough is noted on water vapor imagery
over the western Gulf with axis extending from 31N91W to a base 
over the SW Gulf waters near 21N94W. The trough supports a surface
trough extending from 28N86W to 24N87W to 22N93W to 20N95W. 
Scattered showers and isolated tstms are occurring within 90 nm 
either side of the boundary. Otherwise...generally gentle to 
moderate E-SE winds prevail across the basin this morning on the 
southwestern periphery of a surface ridge anchored by a 1027 mb 
high centered offshore of the Carolinas near 36N73W. The 
troughing moving over the basin will strengthen the current 
surface troughing across the eastern waters and a frontal wave 
across the western waters through early Wednesday with fresh to 
strong northerly winds expected to materialize by Wednesday 
afternoon into the evening. Global models indicate cyclogenesis 
across central and eastern portions of the basin Wednesday night.

Southwesterly flow aloft prevails over the western Caribbean with
a ribbon of mid-level energy stretching from over the Windward
Passage region W-SW to over portions of Central America in the
vicinity of Honduras and El Salvador. This mid-level energy is
supporting a surface trough analyzed from 12N78W to 19N75W. 
Widely scattered showers and isolated tstms are occurring N of 15N
between 70W-80W. A portion of this activity extends N of the
Windward Passage region in the Atlc waters. Otherwise...moderate 
trades are noted E of 77W and moderate to occasional fresh NE 
winds are occurring W of 77W. This pattern is forecast to persist
through Thursday night.

A surface trough lies to the SW of the island with widely 
scattered showers and isolated tstms occurring generally W of 
the island this morning across the Windward Passage region. The 
surface troughing will be slow to move and dissipate through 
Wednesday...so little change is expected through mid-week.

A cold front extends into the discussion area near 32N55W and 
continues SW to 29N61W becoming stationary to the NW Bahamas and
offshore waters of southern Florida. Isolated showers are 
occurring within 60 nm either side of the front. To the N of the 
front...surface ridging prevails anchored by a 1027 mb high 
centered offshore of the Carolinas near 36N73W. SE of the 
front...mid-level shortwave troughing is in the vicinity of 
24N66W and supports a surface trough analyzed from 22N68W to
28N62W. Scattered showers and isolated tstms are occurring from 
20N-28N between 57W-70W...and from 20N-23N between 70W-77W. 
Farther east...another middle to upper level trough is noted in 
the vicinity of 25N39W supporting a 1012 mb low centered near 
24N38W with the associated stationary front extending SW from the
low to 19N50W to 22N61W. Scattered showers and isolated tstms are
occurring within 75 nm either side of the front. This low links 
up with a 1007 mb low centered near 32N27W by way of a cold front
extending from 32N27W to 24N34W then stationary into the 1012 mb
low. Scattered showers and isolated tstms are occurring generally
N of 25N between 16W-37W.

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Page last modified: Tuesday, 21-Nov-2017 10:34:22 UTC