000 AXNT20 KNHC 281720 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1220 PM EST WED DEC 28 2016 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 1700 UTC. ...MONSOON TROUGH/ITCZ... The Monsoon Trough extends across Africa into the east Tropical Atlantic near 04N09E to 02N02W. The ITCZ continues from 02N02W 05N09W to 01N30W to 02N42W. The ITCZ resumes from 09N42W to 09N59W. Scattered moderate and isolated strong convection is seen from 03S to 03N between 03E and 04W. Clusters of scattered moderate to isolated strong convection are observed from 00N to 04N between 05W and 23W, within 90 nm either side of a line from 02S31W to 04N42W and from 07N to 10N between 46W and 57W. ...DISCUSSION... ...GULF OF MEXICO... An upper ridge extends northeastward from the gulf coast of Mexico near Veracruz to the Florida big bend. A shortwave upper trough is exiting the extreme southeastern Gulf toward the northwestern Caribbean. A surface ridge is situated along the northern Gulf coast from the mouth of the Mississippi to the Florida big bend. The ridge is anchored by 1022 mb high pressure centered just south of the Florida panhandle. A weakening surface trough hugs the coast of Mexico from Veracruz to La Pesca. Another weak surface trough heads northward into the Bay of Campeche from 18N94W to 21N92W. Only minimal shower coverage was associated with both of these troughs. The remainder of the Gulf remains under fair weather. Warm, moist, southeasterly surface flow will support patchy fog over far west and north-central Gulf through tonight. A cold front is expected to enter the Gulf on Thursday, followed by strong northwest winds and building seas. The front will quickly move over the central and eastern Gulf by early Friday. High pressure will build southeast behind the front over the north central Gulf by Saturday morning. ...CARIBBEAN SEA... An upper ridge extends from South America across Colombia and the Caribbean over the Windward Passage and into the west Atlantic between upper troughs over Cuba and just east of the Windward Islands. Mostly fair weather and isolated showers are observed across the Caribbean. The west Atlantic surface ridge is maintaining fresh to strong northeast trade winds over the Caribbean. Winds will diminish tonight through Friday as the surface ridge weakens in response to a cold front passing to the north along 30N. Strong northeast trade winds will continue to pulse just north of the coast of Colombia through early Saturday. The high pressure ridge will rebuild in the wake of the cold front to the north of the basin by Sunday, causing wind speeds to increase. ...HISPANIOLA... Mainly fair weather remains in place across the island. A brief, isolated shower remains possible today and tonight. This quiet weather scenario will remain in place through Sunday. ...ATLANTIC OCEAN... The upper ridge over the Caribbean extends through the Windward Passage over the west Atlantic to near 32N53W. A surface ridge covers the central and west Atlantic. The ridge is anchored by a 1028 mb high centered near 32N50W. An upper trough over the east/central Atlantic is supporting a cold front that extends through 32N26W to 23N35W, which continues as a dissipating boundary to 20N52W. An upper ridge extends westward from the African coast near 10N to near 08N40W. Deep layer flow from the WSW between the ridge and an upper low centered near 35N32W is advecting tropical moisture northeastward from the ITCZ within 210 nm of a line from 10N45W to 19N38W to 21N22W. The weakened west Atlantic surface ridge will linger through Thursday. A cold front will move southeastward from Florida Thursday evening and reach from Bermuda to central Cuba Friday evening. High pressure will shift eastward from the northern Gulf to north of the Bahamas by Saturday evening. For additional information please visit http://www.hurricanes.gov/marine $$ McElroy