000 AXNT20 KNHC 012343 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 705 PM EST THU MAR 01 2012 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...THE ITCZ/THE MONSOON TROUGH... THE MONSOON TROUGH MEANDER ALONG ABOUT 11N ACROSS W AFRICA TO THE COAST NEAR 12N16W WHERE IT TERMINATES. BROAD AND WEAK CYCLONIC FLOW IS FOUND S OF THIS OFF THE COAST OF W AFRICA. THE ITCZ BEGINS FROM NEAR 03N18W TO THE EQUATOR NEAR 43W THEN TO THE NE COAST OF BRAZIL NEAR 01S47W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS NOTED WITHIN 60 NM OF THE ITCZ AXIS E OF 29W. SCATTERED MODERATE TO STRONG CONVECTION IS NOTED WITHIN 150 NM N AND 120 NM S OF AXIS W OF 29W. ...DISCUSSION... THE GULF OF MEXICO... UPPER LEVEL RIDGING DOMINATING THE GULF DURING THE PAST FEW DAYS HAS SHIFTED SLIGHTLY WWD AND FLATTENED DURING THE PAST 24 HOURS AS SW N ATLC TROUGH AXIS HAS CONTINUED TO DIG S AND SW ACROSS THE W HALF OF CARIBBEAN. CONDITIONS ALOFT ACROSS THE GULF HAVE THUS DESTABILIZED SOMEWHAT TODAY. THE ATLC HIGH PRES RIDGE EXTENDS W-SW ACROSS SRN FLORIDA THEN W ALONG 25N TO 93W... YIELDING LIGHT TO MODERATE SLY RETURN FLOW ACROSS THE BASIN PER RECENT SCATTEROMETER PASSES. MILD WINDS AND STRONG ANTICYCLONIC TURNING ACROSS THE NE GULF AGAIN ALLOWED FOR LOW STRATUS AND FOG TO LINGER INTO THE AFTERNOON HOURS ACROSS MUCH OF THE BIG BEND REGION TODAY...WITH AREAS OF LOW STRATUS STILL LINGERING ACROSS COASTAL ZONES FROM FROM JUST N OF TAMPA BAY TO THE FLORIDA PANHANDLE. A FRONTAL SYSTEM HAS STALLED THIS AFTERNOON ACROSS CENTRAL PORTIONS OF THE N GULF STATES BUT WILL LIFT N OF THE REGION LATE TONIGHT AND FRI AS LLVL RETURN FLOW INCREASES IN ADVANCE OF NEXT COLD FRONT APPROACHING SE TEXAS COASTAL WATERS FRI AFTERNOON. SLY WINDS ARE EXPECTED TO INCREASE TO AROUND 20 KT ACROSS MOST OF THE W HALF OF THE BASIN FRI IN ADVANCE OF THIS NEXT FRONT. THE CARIBBEAN SEA... IN THE UPPER LEVELS...A SHARP MID TO UPPER LEVEL TROUGH EXTENDS FROM THE W CENTRAL ATLC SW ACROSS THE E END OF HISPANIOLA... ACROSS NW COSTA RICA AND INTO THE TROPICAL EPAC. STRONG SUBSIDENCE IS SEEN IN WATER VAPOR IMAGERY NW OF THE TROUGH FROM S OF JAMAICA TO SRN NICARAGUA AND NW COSTA RICA. STRONG CYCLONIC TURNING WITHIN THE TROUGH AXIS ACROSS THE MONA PASSAGE HAS ACTED TO ENHANCE LLVL MOISTURE AND SHOWERS PASSING ACROSS ERN HISPANIOLA...PUERTO RICO...THE FAR NW LEEWARD ISLANDS AND ADJACENT WATERS THIS AFTERNOON...YIELDING ISOLATED TSTMS THAT WERE CONTINUING ACROSS SW PUERTO RICO. AT LOWER LEVELS...A PRONOUNCED SURFACE PRESSURE GRADIENT FROM AN EXTENSION OF THE BERMUDA HIGH WELL NORTHEAST OF THE CARIBBEAN TO A 1006 MB LOW ALONG THE COLOMBIAN COAST NEAR 6N76W HAS WEAKENED SLIGHTLY TODAY...BUT CONTINUES TO YIELD A BROAD ZONE OF TRADEWINDS 20 KT AND HIGHER S OF 16N AND E OF 80W. A GALE WARNING IS CURRENTLY IN EFFECT FOR THE AREA OF STRONGEST WINDS OFF THE COAST OF COLOMBIA...BUT RECENT SCATTEROMETER PASSES SUGGEST THAT WINDS MAY HAVE DIMINISHED TO BELOW GALE FORCE THERE. GLOBAL MODEL GUIDANCE SUGGEST WINDS PULSING TO GALE FORCE DURING THE LATE NIGHT AND EARLY MORNING HOURS ACROSS THIS AREA EACH OF THE NEXT SEVERAL DAYS. A LARGE AREA OF MULTI LAYERED CLOUDS WITH SCATTERED TO NUMEROUS SHOWERS AND SCATTERED TSTMS CONTINUES TO AFFECT THE SE CARIBBEAN AND WINDWARD ISLANDS S OF ANTIGUA THIS AFTERNOON. THIS IS ASSOCIATED WITH A WEAK LOW-LEVEL DISTURBANCE ALONG 63W/64W...AND A LOW LEVEL WIND SURGE BEHIND IT. TOTAL PRECIPITABLE WATER IMAGERY INDICATES ENHANCED MOISTURE BETWEEN 54W AND 67W SOUTH OF 15N...BUT HAS BECOME SHEARED TO THE NE TO 17N JUST E OF THE LEEWARDS DUE TO THE MID TO UPPER TROUGH. SCATTERED TO NUMEROUS CONVECTION IS EXPECTED DURING THE NEXT 24 HOURS ACROSS THE CARIBBEAN S OF 15N AND PORTIONS OF NORTHERN VENEZUELA AS THE WEAK DISTURBANCE MOVES WESTWARD. STRONG CONVECTION IS EXPECTED THROUGH LATE THIS EVENING ACROSS THE WINDWARDS...SOUTHERN LEEWARDS AND ADJACENT WATERS. THE ATLANTIC OCEAN... A MODEST AZORES-BERMUDA RIDGE EXTENDS ACROSS THE NORTH ATLANTIC ALONG ABOUT 32N THEN CONTINUES SW ACROSS OUR NORTHERN BORDER NEAR 52W AND THROUGH SOUTHERN FLORIDA...INTERRUPTED BY A LLVL TROUGH ALONG 62W/63W. GENERALLY WEAK TO MODERATE NE TO E TRADEWINDS PREVAIL ACROSS THE AREA N OF 20N...BECOMING SE TO S WINDS W OF 67W. S OF 20N...NE TRADEWINDS NEAR 20 KT PREVAIL N OF 10N...WHILE ACTIVE CONVECTION DESCRIBED ABOVE IN THE E CARIBBEAN EXTENDS E TO 55W AND CONTINUES TO AFFECT THE WATERS E OF THE LESSER ANTILLES. E OF THIS ACTIVE WEATHER...VERY STABLE LLVL CONDITIONS PREVAIL N OF THE ITCZ EWD TO THE COAST OF AFRICA AS A WELL ESTABLISHED E TO W LLVL RIDGE ACROSS THE CENTRAL AND E ATLC HAVE ALLOWED FOR RECENT LARGE PLUMES OF SAL TO MOVE ACROSS THE TROPICS. A NEW PLUME OF SAL AND VERY DRY AIR HAS MOVED OFF OF W AFRICA AND ACROSS THE CAPE VERDES TODAY...WITH SKIES NEARLY CLEAR THERE. DRIER AIR AND IMPROVING WEATHER CONDITIONS ARE EXPECTED ACROSS THE TROPICAL N ATLC WATERS W OF 55W AND INTO THE LEEWARD ISLANDS BY LATE SAT. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ STRIPLING