AXNT20 KNHC 221036

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
535 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 0600 UTC surface analysis and satellite imagery through 0945 UTC.

...SPECIAL FEATURES... A 1011 mb low is centered near 27N92W and will merge Wednesday with a cold front currently analyzed across SE Texas bringing near gale to gale force northerly winds generally W of a line from 29N90W to 22N97W. The gale force wind field is expected to persist until Thursday night then diminish into strong to near gale force strength by the late Thursday night into early Friday. 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 10N14W to 07N20W. The Intertropical Convergence Zone extends from 07N20W to 05N26W to 06N40W to 08N49W. Widely scattered moderate and isolated strong convection is from 01N-10N between 02W-24W. Widely scattered moderate convection is from 08N-14N between 26W- 33W...and from 03N-11N between 33W-51W. A surface trough is analyzed at the western extent of the ITCZ from 05N51W to 11N49W.


GULF OF MEXICO... Overall middle to upper level troughing is present over the basin this morning 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 SE Texas...as well as a 1011 mb low centered near 27N92W and the associated surface trough extending from the low to 23N96W. Scattered showers and tstms are occurring N of 22N between 87W-97W. Farther east...a 1012 mb low is centered near 29N85W with the associated surface trough extending S-SW from the low center to 26N85W. Scattered showers and isolated tstms are occurring from 24N-27N between 83W-87W. This low will remain nearly stationary and merge with the progressive front and low impacting the western Gulf waters on Wednesday. As noted above... strong to gale force northerly winds are forecast west of the front through Thursday night as the area of low pressure and front sweep across the central and eastern Gulf waters and then 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 morning between an upper level trough over the Gulf of Mexico and an anticyclonic circulation anchored over the eastern Caribbean near 13N64W. A surface trough is analyzed across the western Caribbean from 11N80W to 16N81W and across Cuba near 22N78W. This surface boundary is providing focus for scattered showers and isolated tstms between 74W-84W in the vicinity of the trough axis. Moisture and cloudiness continues to advect northward over this corridor into the SW North Atlc in advance of the approaching upper level trough currently influencing the Gulf of Mexico this morning. 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 morning. 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 morning 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 1012 mb low centered in the NE Gulf of Mexico near 29N85W with the associated stationary front extending east then northeast along 29N81W to 32N77W. Isolated showers are possible within 60 nm either side of the front. This front links into a 1013 mb low centered off the coast of the Carolinas near 34N76W with fresh to strong S-SE winds occurring N of 24N between 58W-74W and scattered showers and tstms noted N of 20N between 65W-76W. The warm front links up with a weakening cold front within the southern periphery of a surface ridge across the central Atlc from 32N43W to 29N52W becoming stationary to 29N60W to 31N69W. 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 22N38W supporting a 1012 mb low nearly collocated with the upper level feature centered near 22N41W. A stationary front extends E-NE from the low to 24N30W and SW from the low to 18N42W to 18N53W. Isolated showers and possible isolated tstms are occurring near the low from 18N-25N between 35W-42W.

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