Atlantic Tropical Weather Discussion (Text)

AXNT20 KNHC 212340

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
640 PM 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 1800 UTC surface analysis and satellite imagery through 
2330 UTC.


A broad area of low pressure is developing over the northern Gulf
of Mexico while high pressure builds over the central US. The 
pressure gradient between these two features will produce near 
gale to gale-force northerly winds south of 21N and west of 95W. 
The gale force wind field is expected to persist until mid 
Thursday morning, diminishing into strong to near gale force 
strength by the afternoon hours 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.

A 1004 mb low centered near 32N22W is producing gale force winds 
across the Meteo-France forecast area of Irving as confirmed by  
scatterometer data. These winds are forecast to diminish below 
gale force by tonight. Please refer to the Meteo-France forecast 
found at www.meteofrance.com/previsions-meteo-marine/bulletin/
grandlarge/metarea2 for more details. 


The monsoon trough extends from the African coast near 10N14W to 
07N20W. The Intertropical Convergence Zone extends from 07N20W  
to the South America Coast near 06N57W. Scattered moderate 
convection is within 200 nm on either side of the boundaries
mainly east of 30W. Scattered showers prevail over the remainder 
of the ITCZ. 



An upper-level trough over the central Gulf of Mexico is 
supporting a 1013 mb surface low near 29N86W. A surface trough
extends from the low to 25N87W, while a warm front is from the
low to 29N82W. This system is supporting clusters of moderate 
noted over the northern half of the basin. Please refer tot he 
section above about the Gale Warning, which is expected to develop
during the next 12-18 hours. A surface trough extends over the 
Bay of Campeche 23N94W to 20N97W. During the next 24 hours the low
over the northeast Gulf will cross north Florida. Another piece 
of energy at the mid to upper levels will enter the northwest Gulf
which will develop another low over this area. A cold front will 
accompany this low enhancing winds/seas.


A surface trough extends over the western Caribbean from 16N80W 
to 11N81W supporting scattered showers mainly west of 80W. Mainly
gentle to moderate winds cover the western Caribbean, while moderate
easterly winds cover the eastern Caribbean. Expect during the 
next 24 hours for the trough to move west with convection. 


Deep moisture in mid to upper level southwest flow continues to 
support showers and isolated thunderstorms over the island. This 
pattern will likely continue through tonight, with a possible 
drying trend expected by late Wednesday as a mid to upper level 
ridge builds over the area.


A frontal system extends across the west-central Atlantic, 
analyzed as a cold front from 31N50W to 27N62W, then as a
stationary front from that point to 28N72W, ending as a warm 
front from 28N72W to 29N81W. Scattered moderate convection
prevails in the vicinity of the boundary mainly west of 70W. Fresh
to strong winds are noted from 27N-30N between 62W-77W. To the 
east, a 1012 mb surface low is centered near 23N39W. A stationary 
frontal boundary extends from the low to 17N53W then weakens 
through 20N61W. Another stationary front extends northeast from 
the low to 25N30W. Scattered showers are noted along the frontal 
boundaries. Fresh to strong winds are noted from 21N-25N between 
37W-52W. A 1004 mb low north of the area extends its cold front 
from 30N22W to 25N29W. Gale force winds prevail over the southern 
semicircle of the low. Refer to the section above for more 

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Page last modified: Tuesday, 21-Nov-2017 23:40:57 UTC