000 AXNT20 KNHC 212355 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 705 PM EST TUE DEC 21 2010 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. ...ITCZ... ITCZ AXIS IS CENTERED FROM LIBERIA NEAR 6N10W ALONG 4N20W 3N35W 2N50W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM THE EQUATOR TO 4N BETWEEN 9W-14W...AND FROM 1N-7N BETWEEN 14W-19W. ISOLATED MODERATE CONVECTION IS FROM 1N-5N BETWEEN 21W-27W. ISOLATED MODERATE/STRONG CONVECTION IS FROM THE EQUATOR TO 8N BETWEEN 41W-47W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS ALONG THE NE COAST OF SOUTH AMERICA FROM THE EQUATOR TO 6N W OF 50W. ...DISCUSSION... GULF OF MEXICO... MAINLY WEST-NORTHWESTERLY FLOW ALOFT COVERS THE GULF OF MEXICO AROUND AN UPPER LEVEL RIDGE COVERING MUCH OF THE CENTRAL UNITED STATES. THE UPPER RIDGE SUPPORTS A SURFACE RIDGE ANCHORED BY A 1023 MB HIGH CENTERED OVER THE GULF COAST OF FLORIDA NEAR 29N83W. WEAK ANTI-CYCLONIC FLOW IS AROUND THE RIDGE WITH STRONGER SOUTHERLY WINDS UP TO 15 KT W OF 88W. DRY AIR AND SUBSIDENCE ALOFT ARE MAINTAINING MOSTLY CLEAR SKIES ACROSS THE BASIN WITH THE EXCEPTION OF AN AREA OF STRATOCUMULUS CLOUDS IN THE N CENTRAL GULF N OF 26N BETWEEN 85W-94W. EXPECT SURFACE RIDGING TO DOMINATE THE BASIN FOR THE NEXT SEVERAL DAYS KEEPING CONDITIONS FAIR. CARIBBEAN SEA... THE DRY AIR AND SUBSIDENCE ALOFT THAT COVERS THE GULF OF MEXICO IS ALSO IMPACTING MUCH OF THE NRN AND WRN CARIBBEAN KEEPING CONDITIONS FAIR. A LONGWAVE UPPER TROUGH OVER THE W ATLC SUPPORTS A COLD FRONT THAT CONTINUES AS A SURFACE TROUGH INTO THE CARIBBEAN THROUGH ANTIGUA NEAR 17N61W ALONG 15N68W TO 13N68W. SCATTERED SHOWERS/POSSIBLE THUNDERSTORMS ARE WITHIN 75 NM EITHER SIDE OF THE AXIS. A SECOND SURFACE TROUGH IS FARTHER W ALONG 17N74W TO 13N71W...AS INDICATED BY A WINDSAT SCATTEROMETER PASS. THE PASS REVEALS NE WINDS UP TO 20 KTS ARE NE OF THE TROUGH AXIS WITH WEAKER WINDS TO THE SW. CONVERGENCE NEAR THE TROUGH IS SUPPORTING SCATTERED SHOWERS/POSSIBLE THUNDERSTORMS WITHIN 60 NM EITHER SIDE OF THE AXIS. POSSIBLE ISOLATED SHOWERS ARE ALSO N OF 17N BETWEEN 63W-71W. BETWEEN BARBADOS AND SAINT VINCENT IS A 1009 MB SURFACE LOW CENTERED NEAR 13N60W WITH A SURFACE TROUGH EXTENDING THROUGH THE CENTER ALONG 16N55W 14N59W 11N61W TO 10N62W. BURSTS OF ISOLATED MODERATE CONVECTION ARE WITHIN 90 NM E OF THE LOW CENTER AFFECTING BARBADOS AND WITHIN 45 NM OF THE SRN PORTION OF THE TROUGH AFFECTING TRINIDAD... TOBAGO...AND THE COAST OF VENEZUELA. EXPECT SHOWER ACTIVITY TO CONTINUE ACROSS PORTIONS OF THE ERN CARIBBEAN...AS WELL AS ACROSS THE SRN WINDWARD ISLANDS AS A THE LOW PRESSURE SYSTEM MOVES NORTHWESTWARD OVER THE NEXT 24 HRS. ATLANTIC OCEAN... SURFACE RIDGING CENTERED OVER FLORIDA EXTENDS OVER THE FAR W ATLC KEEPING CONDITIONS GENERALLY FAIR THIS EVENING. A DEEP LAYER TROUGH IS TO THE E SUPPORTING A BROAD LOW PRESSURE SYSTEM IN THE NWRN ATLANTIC WITH AN ASSOCIATED COLD FRONT ENTERING THE DISCUSSION AREA NEAR 32N49W CONTINUING TO THE NRN LEEWARD ISLANDS ALONG 25N53W 17N61W. SCATTERED SHOWERS/POSSIBLE THUNDERSTORMS ARE WITHIN 250 NM AHEAD OF THE FRONT N OF 20N... AND WITHIN 45 NM AHEAD OF THE FRONT S OF 20N. GALE FORCE WINDS ARE BOTH AHEAD OF AND BEHIND THE FRONT WITH A LARGE AREA OF STRATOCUMULUS CLOUDS ALSO BEHIND THE FRONT. TO THE SOUTH...A BURST OF ISOLATED MODERATE CONVECTION ASSOCIATED WITH THE SURFACE TROUGH WITH THE LOW CENTER AFFECTING THE WINDWARD ISLANDS MENTIONED ABOVE IS FROM 14N-17N BETWEEN 50W-55W. ACROSS THE ERN ATLC...A BROAD UPPER LEVEL RIDGE ALONG 40W SUPPORTS A SURFACE RIDGE ANCHORED BY A 1018 MB HIGH NEAR 25N36W PROVIDING GENERALLY FAIR WEATHER ACROSS THIS PORTION OF THE BASIN. AN UPPER LEVEL TROUGH IS TO THE E NE OF THE CANARY ISLANDS TO THE CAPE VERDE ISLANDS SUPPORTING A LOW PRESSURE SYSTEM N OF THE DISCUSSION AREA WITH A FADING FRONTAL BOUNDARY ENTERING THE AREA NEAR 32N14W EXTENDING ALONG 30N22W TO N OF THE AREA NEAR 32N33W. A PRE-FRONTAL SURFACE TROUGH DEPICTS THE SHIFTING CYCLONIC WINDS ALONG 31N13W TO 23N21W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ MONTALVO/HUFFMAN