000 AXNT20 KNHC 210557 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 105 AM EST SAT DEC 21 2013 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0515 UTC. ...SPECIAL FEATURES... GALE FORCE WINDS ARE OCCURRING ACROSS PORTIONS OF THE SW CARIBBEAN SEA...NORTH OF THE COAST OF COLOMBIA...DUE TO STRONG PRESSURE GRADIENT BETWEEN A 1032 MB HIGH CENTERED NE OF BERMUDA NEAR 34N60W AND A 1003 MB LOW CENTERED OVER NORTH COLOMBIA NEAR 6N75W. A 0248 UTC ASCAT PASS SHOWED A SOLID AREA OF 25-30 KT WINDS AND GIVEN THE LOW BIAS OF ASCAT...THERE ARE LIKELY ISOLATED AREAS OF GALE FORCE WINDS STILL OCCURRING. SEE LATEST NWS HIGH SEAS FORECAST UNDER AWIPS/WMO HEADERS MIAHSFAT2/FZNT02 KNHC FOR MORE DETAILS. ...ITCZ/MONSOON TROUGH... THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM THE AFRICAN COAST NEAR 8N13W TO 6N25W TO 4N40W TO THE COAST OF SOUTH AMERICA NEAR 1N50W. SCATTERED MODERATE CONVECTION IS FROM 5N-7N BETWEEN 18W-23W. ...DISCUSSION... GULF OF MEXICO... A 1032 MB HIGH CENTERED NE OF BERMUDA AND AN ASSOCIATED RIDGE AXIS EXTENDING WESTWARD ALONG 30N/31N IS PRODUCING 10-20 KT SE RETURN FLOW OVER THE GULF OF MEXICO. THE FLOW OF WARM AND VERY MOIST AIR OVER THE COOLER SHELF WATERS OF THE GULF OF MEXICO IS RESULTING IN AREAS OF LOW CEILINGS AND FOG MAINLY N OF 25N AND W OF 90W. ADDITIONAL PATCHES OF LOW CLOUDS WERE NOTED OVER THE NE GULF NEAR THE FLORIDA BIG BEND. OTHERWISE MOSTLY CLEAR SKIES PREVAIL. IN THE UPPER LEVELS...RIDGE AXIS EXTENDS FROM AN ANTICYCLONE OVER COLOMBIA NORTHWARD ALONG 80W. SOUTHWESTERLY FLOW ON THE BACKSIDE OF THE RIDGE AND WELL E OF A SHARP UPPER LEVEL TROUGH OVER WESTERN NEW MEXICO IS ADVECTING MID TO UPPER LEVEL MOISTURE OVER TEXAS AND THE NW GULF N OF 27N W OF 90W. STRONG SUBSIDENCE IS OVER THE REMAINDER OF THE GULF. A STRONG COLD FRONT IS FORECAST TO MOVE OFF THE TEXAS COAST LATE SAT AFTERNOON WITH INCREASING NORTHERLY WINDS BEHIND THE FRONT. CARIBBEAN SEA... GALE FORCE WINDS ARE OCCURRING ACROSS PORTIONS OF THE SW CARIBBEAN SEA...NORTH OF THE COAST OF COLOMBIA. SEE SPECIAL FEATURES SECTION ABOVE. A 0248 UTC ASCAT PASS AND SURFACE OBSERVATIONS INDICATED 15-20 KT TRADEWINDS ARE OVER THE REMAINDER OF THE CARIBBEAN SEA E OF 80W...WITH LIGHTER WINDS NOTED W OF 80W. SCATTERED LOW TOPPED SHOWERS ARE OVER THE GULF OF HONDURAS...BELIZE... HONDURAS...AND NICARAGUA. MORE SCATTERED SHOWERS ARE OVER E CUBA...HISPANIOLA...PUERTO RICO...AND THE LEEWARD ISLANDS. WSR-88D IMAGERY FROM SAN JUAN INDICATED SCATTERED SHOWERS SWEEPING ACROSS THE ISLAND WITH CONCENTRATED ACTIVITY ALONG THE N COAST OF PUERTO RICO. IN THE UPPER LEVELS...A RIDGE EXTENDS SE TO NW FROM COLOMBIA ACROSS THE WESTERN CARIBBEAN SEA TO THE GULF/FLORIDA ALONG 80W. STRONG SUBSIDENCE COVERS VIRTUALLY THE ENTIRE CARIBBEAN SEA...EXCEPT OVER THE FAR NW PORTION. THE FAIRLY STABLE CONDITIONS ARE EXPECTED TO PERSIST THROUGH THE WEEKEND. ...HISPANIOLA... SCATTERED LOW TOPPED SHOWERS ARE OVER THE DOMINICAN REPUBLIC AND HAITI IN MODERATE TO FRESH TRADEWIND FLOW. GENERALLY STABLE CONDITIONS ARE EXPECTED THROUGH THE WEEKEND AS STRONG UPPER LEVELS SUBSIDENCE PREVAILS. THE STRONG SUBSIDENCE IS REFLECTED IN VERY DRY AIR ABOVE 700 MB IN THE 00Z SAN JUAN RAOB. ATLANTIC OCEAN... A 1032 MB HIGH IS CENTERED NE OF BERMUDA NEAR 34N60W PRODUCING FAIR WEATHER OVER THE BAHAMAS AND WESTERN ATLANTIC. THE TAIL END OF A STATIONARY FRONT ENTERS THE DISCUSSION AREA NEAR 32N45W. ANOTHER 1034 MB HIGH IS CENTERED OVER THE FAE NE ATLANTIC NEAR 37N16W. ELSEWHERE...FRESH TO STRONG NORTHEASTERLY WINDS ARE OCCURRING IN THE REGION TO WEST OF THE CAPE VERDE ISLANDS NEAR 16N28W. SCATTEROMETER PASSES MISSED THE AREA EARLIER THIS EVENING. A SURFACE TROUGH CENTERED OVER THE CENTRAL TROPICAL ATLANTIC EXTENDS FROM 18N42W TO 7N40W. SCATTERED LOW TOPPED SHOWERS ARE WITHIN 180 NM W OF THE TROUGH AXIS. A LARGE MID TO UPPER LEVEL LOW IS CENTERED OVER THE E ATLANTIC NEAR 26N33W. THIS LOW IS PRODUCING SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS FROM 20N-32N BETWEEN 23W-32W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ COBB