000 AXNT20 KNHC 022326 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 705 PM EST FRI MAR 02 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 2300 UTC. ...THE ITCZ/THE MONSOON TROUGH... MONSOON TROUGH MEANDERS W ACROSS TROPICAL AFRICA AND EXITS THE W COAST NEAR 09N13W CONTINUING SW TO NEAR 05N18W WHERE IT TRANSITIONS TO ITCZ. THE ITCZ THEN CONTINUES SW TO THE EQUATOR NEAR 26W TO 1.5S32W TO THE EQUATOR ALONG 40W TO THE NE COAST OF BRAZIL NEAR 01N50W. SCATTERED MODERATE CONVECTION WAS NOTED WITHIN 150 NM S OF TROUGH AXIS E OF 15W. SCATTERED TO LOCALLY NUMEROUS MODERATE ISOLATED STRONG CONVECTION WAS NOTED WITHIN 120 NM N AND 90 NM S OF ITCZ AXIS BETWEEN 23W AND 44W. ...DISCUSSION... GULF OF MEXICO...CARIBBEAN SEA AND SW N ATLC... GULF OF MEXICO UPPER RIDGE HAS FLATTENED CONSIDERABLY IN PAST 48 HOURS...AS AN UNUSUALLY STRONG UPPER JET EXTENDED FROM CENTRAL TEXAS NE INTO CENTRAL TENNESSEE...ASSOCIATED WITH ENERGETIC CENTRAL U.S. TROUGH. SUBSIDENCE ACROSS THE GULF HAS THUS DIMINISHED...AND IS MAINLY CONFINED TO THE SE GULF AND STRAITS OF FLORIDA. THIS JET ENERGY HAS ALSO SHIFTED UPPER RIDGE AXIS FORWARD...NOW EXTENDING FROM THE YUCATAN PENINSULA NEWD TO THE W ATLC WATERS OFF OF CAPE HATTERAS. DOWNSTREAM UPPER TROUGH HAS SHIFTED EWD INTO THE CENTRAL ATLC...AND EXTENDS SW IN A TUTT LIKE FASHION ACROSS THE MONA PASSAGE AND TO THE SW CARIBBEAN AND ADJACENT PORTIONS OF CENTRAL AMERICA AND TROPICAL EPAC. WATER VAPOR IMAGERY CONTINUES TO SHOW VERY STRONG SUBSIDENCE ALONG NW FLANKS OF TROUGH...FROM NEAR 15N77W SW ACROSS THE NICARAGUA-COSTA RICA BORDER TO THE TROPICAL EPAC NEAR 10N90W. AT LOW LEVELS...ATLC HIGH PRES RIDGE HAS SHIFTED SLIGHT EWD TODAY AND ALLOWED FOR SURFACE WIND FLOW TO OPEN UP ACROSS THE ENTIRE GULF OF MEXICO...YIELDING SLY WINDS 15-20 KT W OF 85W AND 10-15 KT E OF 85W THIS AFTERNOON. A COLD FRONT HAS MOVED SE INTO ERN TEXAS THIS AFTERNOON...WITH STRONG CONVECTION ALONG AND AHEAD OF THE FRONT INTO THE GREAT LAKES REGION. THIS FRONT IS FORECAST TO MOVE INTO THE NW GULF EARLY SAT MORNING AND REACH FROM THE FLORIDA BIG BEND REGION TO ERN BAY OF CAMPECHE WITHIN 24 HOURS. NLY GALES ARE EXPECTED BEHIND THE FRONT ACROSS SW PORTIONS OF THE GULF BEFORE SUNSET SAT. WINDS WILL SHIFT S TO SW AT 20-25 KT AHEAD OF THE FRONT ACROSS CENTRAL AND NE PORTIONS OF THE GULF ON SAT...AND FUEL STRONG TSTMS ALONG AND AHEAD OF THE FRONT DURING THE AFTERNOON. THE ATLC HIGH PRES RIDGE IS NOW ANCHORED ON A 1030 MB HIGH ACROSS THE NE ATLC NEAR 34N15W EXTENDING SW TO THE CENTRAL ATLC NEAR 45W THEN W ALONG 25-26N ACROSS THE W ATLC AND THEN MORE NW TO N FLORIDA. SUFFICIENT PRES GRADIENT CONTINUES ACROSS THE CARIBBEAN TO PRODUCE FRESH NE TO E TRADEWINDS E OF 80W...WITH RECENT SCATTEROMETER PASSES SHOWING A SMALL AREA OF WINDS 25-30 KT OFF THE COAST OF COLOMBIA. ABUNDANT MOISTURE POOLED ACROSS THE E CARIBBEAN AND ADJACENT TROPICAL ATLC 24 HOURS AGO HAS WEAKENED AS DRIER AIR ASSOCIATED WITH SAL HAS MIXED ACROSS THE E AND NE CARIBBEAN. SMALL PATCHES OF LLVL CLOUDS AND SHOWERS CAN BE SEEN MOVING W AND NW ACROSS THE NE CARIB AND ADJACENT ATLC...AND ALSO ACROSS THE SRN CARIB FROM THE A-B-C ISLANDS EWD. ARCH CLOUDS AND SQUALLS WERE NOTED THIS AFTERNOON ACROSS THIS AREA...A FURTHER CONFIRMATION OF SAL MIXING INTO A MOIST AND UNSTABLE REGION. SCATTERED MODEST SHOWERS EMBEDDED IN THE MODERATE ELY TRADE WINDS ARE MOVING ACROSS THE TROPICAL ATLC WATERS WWD INTO THE LESSER ANTILLES. SAL WILL CONTINUE TO ADVECT ACROSS THE LESSER ANTILLES AND ERN CARIB OVER THE NEXT 24 HOURS TO DIMINISH SHOWER COVERAGE THERE. SKIES WERE GENERALLY CLEAR ACROSS THE SW N ATLC WATERS DUE TO SUBSIDENCE BEHIND THE UPPER TROUGH...AND STRONG ANTICYCLONIC TURNING IN THE LOW LEVELS. A FEW NARROW CONVERGENCE LINES WERE SEEN ACROSS N PORTIONS OF THE AREA WITH EMBEDDED WEAK SHOWERS. EASTERN ATLC OCEAN... UPPER LEVEL RIDGING REMAINS ANCHORED ACROSS THE DEEP TROPICS... EXTENDING FROM THE GULF OF GUINEA AND ADJACENT TROPICAL AFRICA WWD TO NRN PORTIONS OF S AMERICA...S OF 13N...BUT HAS AMPLIFIED ACROSS THE CENTRAL ATLC ALONG 40W IN ADVANCE OF THE UPPER TROUGH. AT THE SURFACE...FRESH NELY FLOW WAS DEPICTED BY SCATTEROMETER PASSES LATE THIS MORNING FROM 14N-25N E OF 40W...THEN TURNED MORE NLY INTO THE DEEP TROPICS...WHICH HAS FORCED THE ATLC ITCZ S OF THE EQUATOR BETWEEN 26W AND 40W...AS WELL AS AIDED IN INITIATING ACTIVE CONVECTION ALONG THE ITCZ. OTHERWISE...SAL AND STABLE LOW TO MIDDLE ATMOSPHERIC CONDITIONS PREVAIL ACROSS THE TROPICAL ATLC E OF 40W. THE ATLC RIDGE IS EXPECTED TO SHIFT E DURING THE NEXT 24 HOURS AND WEAKEN THE PRES GRADIENT AND WINDS E OF 40W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ STRIPLING