000 AXNT20 KNHC 112349 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 705 PM EST THU DEC 11 2008 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...METEOROLOGICAL ANALYSIS...WEATHER OBSERVATIONS...AND RADAR. BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...THE ITCZ... THE ITCZ IS CENTERED ALONG 8N13W 5N30W 7N45W 9N56W 8N61W. A SURFACE TROUGH REMAINS EMBEDDED WITHIN THE ITCZ ALONG 57W SOUTH OF 13N. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 5N-10N BETWEEN 50W-57W. SIMILAR CONVECTION IS ALSO NOTED WITHIN 100 NM N OF AXIS BETWEEN 44W-50W. ELSEWHERE...SCATTERED MODERATE CONVECTION IS FROM 5N-8N BETWEEN 23W-28W. ...DISCUSSION... GULF OF MEXICO... AN EXTRATROPICAL CYCLONE CURRENTLY CENTERED OVER THE CAROLINAS IS PRODUCING A WIDE VARIETY OF PRECIPITATION OVER THE SE CONUS. A COLD FRONT EXTENDS FROM THIS LOW ACROSS THE SE COAST OF FLORIDA AND WESTERN CUBA INTO THE CARIBBEAN SEA. A REINFORCING COLD FRONT IS BEHIND STRETCHING FROM THE FLORIDA PANHANDLE ACROSS THE CENTRAL GULF NEAR 25N90W TO 23N94W. A DEEP LAYERED TROUGH PRESENTLY IMPACTING THE E CONUS AND THE GULF REGION SUPPORTS THESE FRONTS. A BAND OF SHOWERS AND TSTMS IS WITHIN 120 NM E OF THE FRONT WHILE BROKEN TO OVERCAST STRATOCUMULUS CLOUDS COVERS MUCH OF THE GULF DUE TO THE COLD AIR ADVECTION OVER RELATIVELY WARM WATERS. THICK LOW LEVEL CLOUDS ARE BANKED UP AGAINST THE MOUNTAINS IN SE MEXICO COVERING ALSO THE BAY OF CAMPECHE. A SFC RIDGE CENTERED ON A 1026 MB HIGH LOCATED OVER N MEXICO IS BUILDING IN. THE TIGHT PRESSURE GRADIENT BETWEEN THIS SURFACE RIDGE AND THE SURFACE LOW OVER THE CAROLINAS IS RESULTING IN GALE FORCE WINDS ACROSS THE MIDDLE AND E GULF WHERE A GALE WARNING IS IN EFFECT. SURFACE OBSERVATIONS AND AN EARLIER ASCAT PASS CONFIRMED THESE WIND SPEEDS. ADDITIONALLY...STRONG N TO NE SURFACE WINDS ARE BLOWING THROUGH THE ISTHMUS OF TEHUANTEPEC RESULTING IN STORM FORCE WINDS IN THE E PACIFIC REGION. CARIBBEAN SEA... AS OF 2100 UTC...A COLD FRONT IS OVER WESTERN CUBA...THE NW CARIBBEAN AND N HONDURAS NEAR 15N86W. HAVANA CUBA REPORTED STRONG TSTMS AND GUSTY WINDS OF 18 KT WITH THE PASSAGE OF THE FRONT DURING THE AFTERNOON. SIMILAR WEATHER CONDITIONS WERE REPORTED IN N HONDURAS. LOW/MID CLOUDS LINGERING BEHIND THE FRONT ARE NOTED OVER THE NW CARIBBEAN...PARTS OF THE YUCATAN PENINSULA...BELIZE...GUATEMALA AND HONDURAS. THE FRONT WILL CONTINUE TO MOVE EWD ACROSS CENTRAL CUBA AND THE CAYMAN ISLANDS TONIGHT. MODERATE TO STRONG NLY WINDS OF 20 TO 25 KT ARE EXPECTED IN THE WAKE OF THE FRONT OVER THE NW CARIBBEAN TONIGHT AND FRI. THE REMAINDER OF THE CARIBBEAN SEA REMAINS UNDER THE INFLUENCE OF A STRONG HIGH PRES SYSTEM...ANALYZED 1040 MB...NEAR THE AZORES. PATCHES OF LOW LEVEL MOISTURE CARRIED BY THE TRADE WINDS CONTINUES TO MOVE EWD AROUND THE PERIPHERY OF THIS SFC HIGH WHICH IS ALSO PRODUCING A WIDE SWATH OF MODERATE TO STRONG ELY WINDS ACROSS THE ATLANTIC OCEAN AND THE E-CENTRAL CARIBBEAN...WITH THE STRONGEST WINDS NEAR THE COAST OF COLOMBIA. SATELLITE IMAGERY REVEALS A BAND OF BROKEN SHALLOW MOISTURE WITH EMBEDDED MAINLY LIGHT SHOWERS EXTENDING FROM THE LEEWARD ISLANDS TO JAMAICA. ALOFT...A RIDGE WITH AXIS ALONG 76W DOMINATES MOST OF THE BASIN. MID/UPPER-LEVEL MOISTURE CONTINUES STREAMING ACROSS CENTRAL AMERICA AND THE W CARIBBEAN IN SOUTHWESTERLY FLOW ALOFT. SCATTERED MODERATE CONVECTION IS OVER E PANAMA IN THE VICINITY OF A 1008 MB SURFACE LOW LOCATED NEAR 9.5N77W. UPPER DIFFLUENCE ASSOCIATED WITH THE AFOREMENTIONED RIDGE IS ENHANCING THIS ACTIVITY. ATLANTIC OCEAN... A STRONG CUT-OFF LOW SPINNING OVER THE SE CONUS SUPPORTS A 999 MB SURFACE LOW SITUATED OVER THE CAROLINAS. THE ASSOCIATED COLD FRONT ENTERS THE FORECAST AREA NEAR 32N79W THEN CONTINUES SW ACROSS SE FLORIDA AND WESTERN CUBA INTO THE CARIBBEAN SEA. COLD ADVECTION BEHIND THE FRONT WILL KEEP TEMPS IN THE MID TO UPPER 60S TO THE LOWER 70S IN SOUTH FLORIDA THIS FRIDAY. SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS ARE ALONG AND AHEAD OF THE COLD FRONT OVER THE W ATLC CURRENTLY AFFECTING THE NW BAHAMAS. GALE FORCE WINDS ARE BLOWING AHEAD OF THE FRONT N OF THE NW BAHAMAS AND WEST OF 77W DUE TO THE STRONG PRES GRADIENT BETWEEN THE SURFACE LOW OVER THE CAROLINAS AND THE STRONG SFC HIGH OVER THE ATLANTIC OCEAN. SUBSIDENCE AROUND THIS 1040 MB SURFACE HIGH CENTERED NEAR THE AZORES IS GENERALLY SUPPORTING FAIR WEATHER CONDITIONS ACROSS MUCH OF THE E-CENTRAL ATLC. HOWEVER... AN UPPER LOW CENTERED NEAR 27N48W IS PRODUCING SCATTERED SHOWERS FROM 21N-26N BETWEEN 41W-48W. THIS SFC HIGH IS ALSO GENERATING A WIDE SWATH OF MODERATE TO STRONG ELY WINDS ACROSS THE OCEAN PARTICULARLY FROM 20N-32N BETWEEN 30W-60W. ACROSS THE DEEP TROPICS...A MAINLY WESTERLY FLOW ALOFT IS PRESENT. A JET-STREAM BRANCH WITH CORE WINDS OF 70-90KT CROSSES JUST N OF THE CAPE VERDE ISLANDS. $$ GR