000 AXNT20 KNHC 181736 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 105 PM EST FRI DEC 18 2015 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 1715 UTC. ...SPECIAL FEATURES... A COLD FRONT EXTENDS FROM NEAR OCALA FLORIDA THROUGH 24N87W TO 18N93W. A RECENT ASCAT-B SCATTEROMETER PASS CONFIRMED GALE FORCE WINDS IN THE SW GULF BEHIND THE FRONT. SEAS ARE UP TO 12 FT. FRESH TO STRONG NORTHERLY WINDS ARE ELSEWHERE BEHIND THE FRONT. A PRE-FRONTAL TROUGH EXTENDS FROM NEAR CAPE CORAL FLORIDA TO THE NORTHERN YUCATAN PENINSULA NEAR 21N88W. SCATTERED MODERATE CONVECTION IS N OF 22.5N AHEAD OF THE FRONT. THE FRONT IS FORECAST TO MOVE SE OF THE BASIN TONIGHT AS 1030 MB HIGH PRESSURE CURRENTLY OVER THE TEXAS HILL COUNTRY NEAR 31N98W BUILDS EASTWARD. WINDS WILL DIMINISH BELOW GALE FORCE THIS EVENING. ...ITCZ/MONSOON TROUGH... A TROUGH EXTENDS FROM 01N AND THE PRIME MERIDIAN TO 03N10W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 05N14W TO 04N26W TO 04N35W THEN RESUMES FROM 05N39W TO 01N48W. A SURFACE TROUGH IS EMBEDDED IN THE ITCZ FROM 08N34W TO 02N38W. SCATTERED MODERATE CONVECTION IS FROM 05N-07N BETWEEN 32W-40W. ...DISCUSSION... GULF OF MEXICO... THE MAIN WEATHER STORY IS THE COLD FRONT MOVING THROUGH THE GULF AS IS DETAILED IN THE SPECIAL FEATURES SECTION ABOVE. AN UPPER LEVEL TROUGH EXTENDING FROM THE TENNESSEE VALLEY TO CENTRAL TEXAS IS SUPPORTING THE COLD FRONT AT THE SURFACE WITH DRIER AND MORE STABLE AIR EXPECTED TO MOVE INTO THE NW GULF AS THE TROUGH CONTINUES TO MOVE TO THE E-SE. SENSIBLE WEATHER CONDITIONS WILL GRADUALLY IMPROVE FROM NW TO SE AS THE 1030 MB HIGH PRESSURE OVER THE TEXAS HILL COUNTRY MOVES EASTWARD REACHING THE CAROLINAS BY SUN MORNING. AS THE HIGH SHIFTS TO THE E...WINDS WILL VEER TO THE E-SE AT MODERATE TO FRESH LEVELS ACROSS THE MAJORITY OF THE BASIN...EXCEPT IN THE SE PORTION WHERE FRESH TO STRONG NE FLOW WILL PERSIST ALONG WITH 8-11 FT SEAS MAKING FOR HAZARDOUS CONDITIONS FROM THE STRAITS OF FLORIDA TO THE YUCATAN CHANNEL. CARIBBEAN SEA... A MIDDLE TO UPPER LEVEL LOW IS LOCATED OVER THE DOMINICAN REPUBLIC WITH A TROUGH AXIS EXTENDING FROM THE LOW THROUGH 16N74W TO THE SW CARIBBEAN NEAR 10N83W. A SURFACE TROUGH IS LOCATED OVER THE DOMINICAN REPUBLIC WITH SCATTERED SHOWERS AND ISOLATED TSTMS MOVING FROM SE TO NW ACROSS THE ISLAND. ADDITIONAL ISOLATED ACTIVITY IS POSSIBLE IN THE E CARIBBEAN E OF 70W. A RECENT ASCAT PASS ALSO SHOWED A SURFACE TROUGH IN THE WESTERN CARIBBEAN ALONG 82W. SCATTEROMETER DATA AND SURFACE OBSERVATIONS SHOW MAINLY MODERATE TO FRESH TRADES ACROSS THE BASIN...EXCEPT IN THE CENTRAL CARIBBEAN WHERE TRADES ARE FRESH TO STRONG. THESE STRONGER WINDS ARE DUE TO THE COMBINATION OF 1006 MB LOW PRESSURE OVER NORTHERN COLOMBIA NEAR 08N74W AND CENTRAL ATLC RIDGING NE OF THE AREA. THE STRONGER TRADES WILL EXPAND WESTWARD TO THE COAST OF CENTRAL AMERICA SAT AND SAT NIGHT AS THE PRESSURE GRADIENT TIGHTENS OVER THAT AREA. MEANWHILE A COLD FRONT CURRENTLY IN THE SE GULF OF MEXICO IS FORECAST TO SLIP SE OF THE YUCATAN CHANNEL THIS EVENING... REACHING FROM CUBA NEAR 22N81W TO BELIZE NEAR 18N88W BY SAT MORNING...THEN STALLING FROM EASTERN CUBA NEAR 20N78W TO THE GULF OF HONDURAS BY SUN MORNING. FRESH TO STRONG N-NE WINDS AND BUILDING SEAS WILL FOLLOW THE FRONT...UP TO 11 FT NEAR THE YUCATAN CHANNEL. ...HISPANIOLA... A MIDDLE TO UPPER LEVEL LOW IS LOCATED OVER THE DOMINICAN REPUBLIC WITH A TROUGH AXIS EXTENDING FROM THE LOW THROUGH 16N74W. A SURFACE TROUGH IS LOCATED OVER THE DOMINICAN REPUBLIC WITH SCATTERED SHOWERS AND ISOLATED TSTMS MOVING FROM SE TO NW ACROSS THE ISLAND. THE UPPER LOW IS FORECAST TO CONTINUE TO MOVE W-NW THROUGH TONIGHT...THEN WILL FINALLY GET PICKED UP AND SHIFTED EASTWARD WHILE WEAKENING SUN AS A STRONG UPPER TROUGH MOVES IN FROM THE NW. INSTABILITY WILL REMAIN OVER THE AREA UNTIL EARLY NEXT WEEK ALLOWING FOR SCATTERED SHOWERS AND ISOLATED TSTMS TO REMAIN IN THE FORECAST. ATLANTIC OCEAN... A MIDDLE TO UPPER LEVEL RIDGE EXTENDS FROM 32N62W TO CENTRAL CUBA NEAR 23N88W. DRY AND STABLE CONDITIONS ARE EVIDENT ON WATER VAPOR SATELLITE IMAGERY SE OF THE RIDGE AXIS. ISOLATED CONVECTION IS S OF 22N BETWEEN 64W-72W AROUND AN UPPER LOW DESCRIBED IN GREATER DETAIL IN THE HISPANIOLA SECTION. A COLD FRONT CURRENTLY EXTENDING FROM THE NORTHERN FLORIDA PENINSULA THROUGH THE EASTERN GULF OF MEXICO IS APPROACHING THE NW CORNER OF THE BASIN. THAT FRONT IS FORECAST TO MOVE OFFSHORE INTO THE AREA THIS AFTERNOON...REACHING FROM 31N74W TO THE FLORIDA KEYS THIS EVENING...THEN FROM 31N68W TO N CENTRAL CUBA NEAR 23N80W SAT MORNING...THEN FROM 31N62W TO EASTERN CUBA NEAR 21N76W SAT EVENING...AND FINALLY FROM 31N57W TO 27N65W WHERE IT WILL STALL TO EASTERN CUBA. RECENT SCATTEROMETER DATA SHOWED NEAR GALE FORCE WINDS ALONG 31N WITH FRESH TO GALE FORCE SOUTHERLY FLOW AHEAD OF IT ELSEWHERE N OF 29N AHEAD OF THE FRONT. FRESH TO STRONG NORTHERLY WINDS WILL QUICKLY ARRIVE IN THE WAKE OF THE FRONT ALONG WITH BUILDING SEAS OF 7-10 FT. ELSEWHERE...ANOTHER COLD FRONT IS LOCATED FROM 32N26W TO 25N40W TO 24N50W WHERE IT BECOMES STATIONARY TO 26N61W. HIGH PRESSURE AT 1030 MB IS TO THE N OF THE FRONT NEAR 33N52W. SCATTERED SHOWERS CAN BE FOUND WITHIN 60 NM EITHER SIDE OF THE BOUNDARY. MODERATE TO FRESH TRADES PREVAIL ACROSS THE WATERS E OF 60W. THE FRONT WILL WEAKEN AS IT CONTINUES TO MOVE SE-E THROUGH THE NEXT 24-48 HOURS. 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