000 AXNT20 KNHC 211739 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 105 PM EST MON FEB 21 2011 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. ...ITCZ... ITCZ AXIS IS ANALYZED ALONG 6N10W TO 3N20W TO SOUTH OF THE EQUATOR NEAR 30W AND INTO NE BRAZIL NEAR 02S45W. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS FROM 2N-5N BETWEEN 9W AND 14W. SCATTERED MODERATE CONVECTION IS FROM 2N-4N BETWEEN 20W AND 23W AND ALSO FROM 1N-3N BETWEEN 34W AND 36W. ...DISCUSSION... GULF OF MEXICO... AN UPPER LEVEL RIDGE RESIDES ALOFT OVER THE ENTIRE GULF AND THE EASTERN CONUS WITH MOSTLY DRY AIR AND STRONG SUBSIDENCE NOTED ON WATER VAPOR IMAGERY WHICH IS ANTICIPATED TO CONTINUE PROVIDING MOSTLY CLEAR SKIES THROUGHOUT THE DAY TODAY. AT THE SURFACE...A 1022 MB HIGH IS CENTERED IN THE SW NORTH ATLC WATERS THAT EXTENDS A RIDGE AXIS SW-W ACROSS THE FLORIDA PENINSULA INTO THE W GULF. SHIP AND BUOY OBSERVATIONS INDICATE S-SE WINDS IN THE RANGE OF 15 TO 25 KT ARE LOCATED ON THE WESTERN PERIPHERY OF THE RIDGE. THE NEXT WEAK FRONTAL BOUNDARY IS FORECAST TO IMPACT THE NW GULF WATERS BY EARLY TUESDAY AND LIFT BACK NORTHWARD OVER THE GULF COASTAL PLAIN LATE TUESDAY INTO WEDNESDAY. CARIBBEAN SEA... WATER VAPOR IMAGERY INDICATES VERY DRY AIR ALOFT OVER THE CARIBBEAN SEA BASIN TODAY WITH A WEAK UPPER LEVEL LONGWAVE TROUGHING EXTENDING FROM THE WESTERN ATLC OVER THE GREATER ANTILLES AND NORTHERN LEEWARD ISLANDS. AT THE SURFACE...A 1022 MB HIGH IS CENTERED OVER THE W ATLC NE OF THE BAHAMA ISLANDS THAT CONTINUES TO PRODUCE A STRONG PRESSURE GRADIENT OVER MUCH OF THE CARIBBEAN AND RIDGING TO THE W CARIBBEAN. STRONG NE-E WINDS ARE OCCURRING ON THE SOUTHERN PERIPHERY OF THE RIDGE AND ARE EXPECTED TO PERSIST THROUGH LATE TUESDAY AS THE HIGH SETTLES FARTHER SOUTHWARD. OTHERWISE...LOW-LEVEL MOISTURE ASSOCIATED WITH A WEAKENED FRONTAL BOUNDARY TO THE NORTH OF PUERTO RICO AND THE LEEWARD ISLANDS IS ADVECTING ISOLATED SHOWERS OVER MUCH OF THE NE AND NORTH-CENTRAL CARIBBEAN THIS MORNING N OF 14N E OF 72W... INCLUDING PUERTO RICO AND THE US/UK VIRGIN ISLANDS...AND FROM 13N-14N BETWEEN 72W AND 77W. ATLANTIC OCEAN... UPPER LEVEL RIDGING IS MOVING E OFF THE EASTERN CONUS SUPPORTING A 1022 MB HIGH CENTERED NE OF THE BAHAMA ISLANDS NEAR 29N71W. SURFACE RIDGING IS PROVIDING FAIR WEATHER FOR MUCH OF THE AREA W OF 60W. AN UPPER LEVEL TROUGH TO THE E IS SUPPORTING A COMPLEX FRONTAL SYSTEM AT THE SURFACE WITH A REINFORCING COLD FRONT ENTERING THE AREA NEAR 32N45W EXTENDING ALONG 26N50W 22N60W TO 23N67W...A DISSIPATING COLD FRONT ANALYZED ALONG 26N49W 21N58W 20N67W...AND A PREFRONTAL SURFACE TROUGH ALONG 24N48W 19N53W 17N59W. THE REINFORCING FRONT WILL OVERTAKE THE DISSIPATING FRONT AS IT CONTINUES TO WEAKEN. SCATTERED SHOWERS WITH POSSIBLE THUNDERSTORMS ARE WITHIN 300 NM OF THE COLD FRONTS N OF 24N. THE PREFRONTAL SURFACE TROUGH HAS ISOLATED SHOWERS ALONG THE AXIS. SOUTH OF THIS FRONTAL SYSTEM A SURFACE TROUGH IS ALONG NE SOUTH AMERICA ANALYZED ALONG 11N60W 8N57W AND INTO SURINAME NEAR 5N56W. ISOLATED SHOWERS COVER THE AREA FROM 4N-16N BETWEEN 50W-60W. ELSEWHERE E OF 40W...A SURFACE RIDGE ANCHORED BY A 1032 MB HIGH CENTERED NORTH OF THE MADEIRA ISLANDS NEAR 36N17W CONTINUES TO PROVIDE MOSTLY FAIR CONDITIONS ACROSS THE EASTERN ATLC. ALOFT...AN UPPER LEVEL RIDGE EXTENDS FROM EXTENDS FROM NE SOUTH AMERICA TO THE AZORES ISLANDS SUPPORTING THE SURFACE RIDGE...WHILE AN UPPER LEVEL CUT-OFF TROUGH EXTENDS FROM THE CAPE VERDE ISLANDS INTO THE TROPICAL ATLC NEAR EQ30N. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ MONTALVO/WALTON