AXNT20 KNHC 220542

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1242 AM EST Wed Nov 22 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 0000 UTC surface analysis and satellite imagery through 0515 UTC.

...SPECIAL FEATURES... An area of low pressure is expected to develop across the NW Gulf through Wednesday and merge with a cold front currently analyzed across Texas bringing near gale to gale force N-NW winds S of 24N west of the front across portions of the SW Gulf waters. The gale force wind field is expected to persist until Thursday afternoon then diminish into strong to near gale force strength by the Thursday night. See the latest NWS High Seas Forecast under AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC for more details.

...ITCZ/MONSOON TROUGH... The monsoon trough extends from the African coast near 09N13W to 10N25W. The Intertropical Convergence Zone extends from 10N25W to 06N43W to 07N51W to 06N56W. Widely scattered moderate convection is from 01N-09N between 02W-22W...from 03N-14N between 22W- 38W...and from 06N-11N between 40W-60W.


GULF OF MEXICO... Overall middle to upper level troughing is present over the basin this evening with focus on two stronger mid-level shortwave troughs noted over the NW Gulf waters. This vigorous troughing aloft is supporting the special features cold front currently across eastern and south-central Texas...as well as a surface trough analyzed across the western Gulf waters from 21N95W to 26N95W to 29N91W. Scattered showers and tstms are occurring N of 23N between 87W-96W. Farther east...a weak 1013 mb low is centered near 29N85W with the associated surface trough extending S-SW from the low center to 24N88W. Isolated showers and tstms are occurring from 24N-27N between 83W-88W. This low will quickly move NE as the cold front across Texas emerges off the coast by early Wednesday. As noted above...strong to gale force northerly winds are forecast west of the front through Thursday night as an area of low pressure develops across the eastern Gulf waters and moves NE into the SW North Atlc waters by late Friday night. Surface ridging is expected to build in behind the front Saturday and influence the basin the remainder of the weekend.

CARIBBEAN SEA... Southwesterly flow aloft prevails over the western and central Caribbean this evening between an upper level trough over the Gulf of Mexico and an anticyclonic circulation anchored over the eastern Caribbean near 13N65W. A surface trough is analyzed along 80W generally N of 15N providing focus for scattered showers and isolated tstms between 74W-83W. Moisture and cloudiness continues to advect northward over the SW North Atlc in advance of the approaching upper level trough currently influencing the NW Gulf of Mexico this evening. Otherwise...conditions remain relatively tranquil within moderate to fresh trades E of the surface trough. This overall synoptic pattern is forecast to persist through the weekend.

...HISPANIOLA... Clear skies and relatively tranquil conditions are noted across the island this evening. Ongoing convective activity is expected to remain W of the island as surface troughing along 80W will be nearly stationary through the upcoming weekend.

ATLANTIC OCEAN... Southwesterly and divergent middle to upper level flow prevails over the SW North Atlc this evening between an upper level trough over the Gulf of Mexico and upper level ridging anchored over the central Atlc. The troughing to the west supports a weak 1013 mb low centered in the NE Gulf of Mexico near 29N85W with the associated warm front extending generally eastward to 28N70W. Scattered showers and tstms are occurring across a large portion of the SW North Atlc from 22N-32N between 64W-78W. The warm front links up with a weakening cold front within the southern periphery of a surface ridge across the central Atlc from 32N44W to 29N56W to 28N70W. Isolated showers are occurring within 60 nm either side of the front. Farther south...a middle to upper level low is noted on water vapor imagery near 23N38W supporting a 1012 mb low nearly collocated with the upper level feature centered near 22N40W. A stationary front extends E-NE from the low to 24N28W and SW from the low to 18N50W becoming a shear line to 20N61W. Isolated showers and possible isolated tstms are occurring near the low from 20N-25N between 35W-43W.

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