000 AXNT20 KNHC 071754 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 105 PM EST SUN DEC 07 2014 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... ATLC GALE WARNING REMAINS IN EFFECT THROUGH TONIGHT N OF 28N BETWEEN 45W-57W. THESE WINDS ARE BEING GENERATED DUE TO THE TIGHT PRESSURE GRADIENT BETWEEN THE LOW/TROUGH IN THE CENTRAL ATLC AND THE STRONG SURFACE RIDGE ANCHORED JUST N OF THE AZORES. PLEASE SEE THE HIGH SEAS FORECAST UNDER AWIPS/WFO HEADERS MIAHSFAT2/FZNT02 KNHC FOR MORE DETAILS. ATLC THREAT OF NEAR GALE IS EXPECTED OVER THE NEXT 18 HRS IN THE E ATLC OVER THE METEO FRANCE AREA OF IRVING...MADEIRA...METEOR AND CAPE VERDE WITH THE THREAT OF GALE OVER CAPE VERDE. PLEASE SEE THE HIGH SEAS FORECAST WITH METEO FRANCE UNDER WMO HEADER FQNT50 LFPW FOR MORE INFORMATION. ...THE ITCZ/THE MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE E TROPICAL ATLC NEAR 10N14W ALONG 8N17W TO 6N21W WHERE THE ITCZ BEGINS AND CONTINUES ALONG 6N28W TO 6N37W. ISOLATED MODERATE CONVECTION IS FROM 10N TO 13N E OF 18W TO THE COAST OF W AFRICA. SCATTERED MODERATE CONVECTION IS FROM 3N TO 10N BETWEEN 22W AND 33W. ...DISCUSSION... GULF OF MEXICO... AN UPPER TROUGH OVER THE WESTERN ATLANTIC SUPPORTS A COLD FRONT THAT EXTENDS ACROSS N FLORIDA NEAR 29N82W TO 27N90W TO 25N97W. ISOLATED SHOWERS ARE WITHIN 50 NM OF THE FRONT. NE WINDS OF 15 TO 20 KT ARE N OF THE FRONT. N TO NE WINDS OF 10 TO 15 KT ARE S OF THE FRONT. IN THE UPPER LEVELS...AN UPPER LEVEL RIDGE AXIS EXTENDS ACROSS MUCH OF THE GULF WHICH IS PRODUCING SUBSIDENCE ACROSS THE BASIN. THIS IS HELPING TO LIMIT CONVECTION ALONG THE COLD FRONT. OVER THE NEXT 24 HOURS THE COLD FRONT WILL MOVE INTO THE SOUTHERN GULF WHILE DISSIPATING. SHOWERS WILL BE POSSIBLE IN THE CENTRAL AND SOUTHERN GULF THROUGH MONDAY. CARIBBEAN SEA... A BROAD UPPER RIDGE CONTINUES TO DOMINATE THE CARIBBEAN BASIN. THIS RIDGE...COMBINED WITH VERY DRY AIR IN THE MIDDLE TO UPPER LEVELS...IS INHIBITING CONVECTION ACROSS MUCH OF THE BASIN. THE ONLY EXCEPTION IS ACROSS THE SW CARIBBEAN NEAR THE MONSOON TROUGH WHERE SCATTERED MODERATE CONVECTION IS OCCURRING S OF 12N BETWEEN 75W AND 83W. NW SURFACE FLOW OF 10 TO 20 KT DOMINATES THE CENTRAL AND EASTERN CARIBBEAN WITH A SMALL AREA OF WINDS UP TO 25 KT WITHIN 100 NM OF THE COAST OF COLOMBIA. A SURFACE TROUGH EXTENDS FROM THE CENTRAL ATLANTIC...ACROSS THE LEEWARD ISLANDS...AND OVER THE E CARIBBEAN TO 15N64W. DRY AIR AND SUBSIDENCE IS LIMITING CONVECTION ALONG THIS PORTION OF THE TROUGH. NW WINDS AROUND 10 KT ARE N OF THE TROUGH...WITH E WINDS OF 5 TO 10 KT S OF THE TROUGH. OVER THE NEXT 24 HOURS THE UPPER RIDGE WILL FLATTEN OUT AS UPPER LEVEL ZONAL WESTERLIES COVER THE BASIN. DRY AIR WILL CONTINUE TO LIMIT CONVECTION EXCEPT OVER THE SW BASIN. HISPANIOLA... NORTHERLY LOW LEVEL FLOW BETWEEN LOW PRESSURE OVER THE CENTRAL ATLANTIC AND HIGH PRESSURE OVER THE CONUS IS COMBINING WITH DRY AIR IN THE MIDDLE TO UPPER LEVELS TO PRODUCE MOSTLY FAIR WEATHER OVER THE ISLAND. THE BEST CHANCE OF SEEING ANY PRECIPITATION WOULD BE A FAST MOVING SMALL SHOWER OR UPSLOPE SHOWERS. THESE MOSTLY FAIR CONDITIONS ARE EXPECTED TO CONTINUE INTO TUESDAY. ATLANTIC OCEAN... AN UPPER TROUGH MOVING OVER THE W ATLANTIC SUPPORTS A COLD FRONT THAT EXTENDS FROM 31N78W TO N FL NEAR 29N82W. ISOLATED SHOWERS ARE WITHIN 50 NM OF THE FRONT. NORTHERLY WINDS OF 15 TO 20 KT ARE N OF THE FRONT. A PRE-FRONTAL SURFACE TROUGH JUST AHEAD OF THE FRONT EXTENDS FROM 31N75W TO 29N79W. SCATTERED SHOWERS ARE WITHIN 30 NM OF THIS TROUGH. ANOTHER SURFACE TROUGH EXTENDS FROM 26N75W TO 21N75W INCLUDING THE CENTRAL BAHAMAS. SCATTERED SHOWERS ARE WITHIN 50 NM OF THE TROUGH AXIS. THE AXIS OF THE UPPER TROUGH OVER THE W ATLANTIC EXTENDS SE OVER THE CENTRAL ATLANTIC. THIS SUPPORTS A BROAD 1004 MB SURFACE LOW NEAR 26N59W. A SURFACE TROUGH EXTENDS FROM ANOTHER LOW NEAR 34N59W SOUTH THROUGH THE 1004 MB LOW TO 21N59W TO THE LEEWARD ISLANDS...AND OVER THE E CARIBBEAN. CONVECTION ASSOCIATED WITH THESE FEATURES IS DISPLACED E OF THE SURFACE FEATURES...SUPPORTED BY LIFT ASSOCIATED WITH THE E SIDE OF THE UPPER TROUGH. STRONG WINDS BETWEEN THE SURFACE LOW AND HIGH PRESSURE NEAR THE AZORES IS PRODUCING GALE FORCE WINDS IN THE CENTRAL ATLANTIC. SEE THE SPECIAL FEATURES SECTION. SCATTERED MODERATE CONVECTION IS FROM 14N TO 31N BETWEEN 47W AND 59W. AN UPPER LOW IS CENTERED OVER THE E ATLANTIC NEAR 25N30W WITH AN UPPER TROUGH EXTENDING SOUTHWARD ALONG 30W TO 15N. ISOLATED MODERATE CONVECTION IS FROM 21N AND 28N BETWEEN 24W AND 31W. OVER THE NEXT 24 HOURS THE COLD FRONT WILL CONTINUE IN THE W ATLANTIC WITH SHOWERS. THE SURFACE LOW WILL LIFT NE TOWARD 35N55W WITH CONVECTION CONTINUING S OF 31 ALONG A TROUGH EXTENDING S OF THE SURFACE LOW. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ LATTO