AXNT20 KNHC 171718

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1218 PM EST Fri Nov 17 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 1200 UTC surface analysis and satellite imagery through 1545 UTC.

...ITCZ/MONSOON TROUGH... The monsoon trough extends from the African coast near 09N13W to 06N24W to 07N30W. The Intertropical Convergence Zone axis extends from 07N30W to 08N38W to 05N52W. Widely scattered moderate convection is from 03N-13N between 18W-42W.


GULF OF MEXICO... NW flow aloft prevails over the Gulf basin this afternoon on the western periphery of an upper level trough extending over the SW North Atlc...southern Florida peninsula...and base over southern Mexico. Mostly stable conditions are noted at the surface as a ridge axis extends from an Ohio River valley anchored 1027 mb high near 40N81W S-SW to the lower Mississippi River valley into the SW Gulf near 21N95W. Skies are mostly clear with the exception of a few possible isolated showers within 60 nm either side of a surface trough analyzed from 18N94W to 23N98W. Otherwise...gentle to moderate anticyclonic winds are forecast through early Friday night. The next cold front is expected to emerge off the Texas and Louisiana coasts by late Saturday into Saturday night. Fresh to strong N-NE winds will follow in wake of the front as it sweeps southeastward through Sunday night into early Monday.

CARIBBEAN SEA... A broad area of lower pressure across the basin continues to be focused on a 1008 mb low centered SW of Hispaniola near 17N73W. A surface trough extends SW from the low to near 11N77W and links up with the monsoon trough axis along 09N/10N supporting scattered showers and strong tstms from 09N-18N between 68W-79W. Otherwise...moderate to occasional fresh northerly winds are noted across the western Caribbean waters generally W of 77W...while trade wind flow E of the surface troughing will continue to be disrupted outside of convection...with gentle to moderate southerly winds prevailing this afternoon through the upcoming weekend. The low is expected to remain nearly stationary SW of Hispaniola and gradually dissipate by Monday.

...HISPANIOLA... Widely scattered showers and isolated tstms are expected to persist across the island the next few days as deep moisture and cloudiness advects NE over the region due to an upper trough to the NW over the SW North Atlc and SE Gulf of Mexico. Convection will likely be more widespread in areal coverage during the afternoon and evening hours due to maximum heating and instability.

ATLANTIC OCEAN... The SW North Atlc is under the influence of an relatively dry middle to upper level trough with axis extending from 32N75W to over the Florida Straits to a base over southern Mexico. However a cold front primarily analyzed N of the discussion area extends from 32N68W to 30N73W providing possible isolated showers from 26N-32N between the front and 65W. More active weather lies to the SE as the upper level troughing has continued to support another cold front entering the discussion area across the central Atlc. The cold front extends from 32N41W SW to 27N51W becoming stationary into a 1009 mb low centered near 24N64W. Weak surface troughing then continues W-SW to the coast of Hispaniola near 20N72W and into the central Caribbean Sea. Scattered showers and widely scattered tstms are occurring across a large area in the vicinity of the troughing and stationary front from 20N-29N between 51W-74W. Other widely scattered showers and isolated tstms are occurring in association with the cold front from 25N-32N between 32W-47W. The frontal troughing is expected to persist across the central Atlc through Saturday night as ridging builds in off the SE CONUS and into the SW North Atlc. Finally...mostly tranquil conditions are noted across the eastern Atlc in the vicinity of a 1018 mb high centered near 28N29W...however a surface trough extends from a weakening 1014 mb low centered SE of the Azores to near 27N23W. Possible isolated showers are N of 27N between 15W-21W...including the Canary Islands.

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