000 AXNT20 KNHC 282341 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 705 PM EST TUE FEB 28 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 2245 UTC. ...THE ITCZ/THE MONSOON TROUGH... THE MONSOON TROUGH MEANDERS ACROSS W AFRICA ALONG 09-10N AND EXITS THE COAST OF GUINEA NEAR 10N13W CONTINUING SW TO NEAR 04N20W...WHERE IT TRANSITIONS TO ITCZ...CONTINUING TO THE EQUATOR NEAR 33W AND THEN EXTENDING JUST S OF THE EQUATOR ALONG 0.5S TO THE COAST OF BRAZIL AT THE MOUTH OF THE AMAZON. ISOLATED TO SCATTERED MODERATE/ISOLATED STRONG CONVECTION WAS NOTED 01.5S-02N BETWEEN 27W AND 33W...AND FROM 03S-03N BETWEEN 31W AND 43W. SCATTERED MODERATE TO STRONG CONVECTION WAS NOTED S OF 06N W OF 45W TO COASTAL ZONES OF S AMERICA. ...DISCUSSION... THE GULF OF MEXICO... A HIGH AMPLITUDE UPPER LEVEL RIDGE CONTINUES TO DOMINATE THE GULF OF MEXICO THIS AFTERNOON...EXTENDING FROM THE TROPICAL EASTERN PACIFIC ALONG 95W...N-NE ACROSS SE MEXICO AND THROUGH THE SW LOUISIANA COAST...CONTINUING BEYOND THE GREAT LAKES REGION. RIDGE AXIS GENERALLY SPANS THE GULF BETWEEN 78W AND 105W...AND IS MAINTAINING A VERY STABLE MIDDLE TO UPPER ENVIRONMENT ACROSS ALL BUT NORTHEASTERN MEXICO. AT THE SURFACE...HIGH PRESSURE CENTERED OVER WESTERN MARYLAND-NE W VA EXTENDS SW AND WEAKLY ACROSS THE NE GULF TO SOUTHERN MEXICO ALONG THE COAST OF VERA CRUZ. HI RES VISIBLE SATELLITE IMAGERY SHOWS THE TYPICAL COASTAL TROUGH JUST OFFSHORE BETWEEN TUXPAN AND TAMPICO MEXICO. OTHERWISE...LIGHT TO MODERATE ANTICYCLONIC FLOW PREVAILS ACROSS THE BASIN...WITH SOUTHERLY RETURN FLOW TO 15 KT OCCURRING N OF 24N W OF 87W. SATELLITE IMAGERY SHOWS BROKEN TO OVERCAST LOW CLOUDS LINGERING ACROSS THE NE GULF...WITH AREAS OF DENSE FOG AND LOW VISIBILITIES STILL BEING REPORTED ACROSS PORTIONS OF THE FLORIDA PANHANDLE AND NORTHERN FLORIDA...AND ARE LIKELY OCCURRING ACROSS THE FAR NE GULF WATERS ATTM. EXPECT THIS SURFACE RIDGING TO REMAIN OVER THE BASIN FOR THE NEXT COUPLE OF DAYS....WITH LITTLE CHANGE IN SURFACE WIND SPEED AND DIRECTION EXPECTED THROUGH THU NIGHT. THE CARIBBEAN SEA... THE UPPER FLOW ACROSS THE CARIBBEAN IS GENERALLY CHARACTERIZED BY CONFLUENCE BETWEEN THE NW FLOW DOWNSTREAM OF THE GULF OF MEXICO RIDGE...SW FLOW ACROSS THE TOP OF UPPER RIDGING ACROSS NRN S AMERICA...AND W FLOW ASSOCIATED WITH A SHORT WAVE TROUGH MOVING ACROSS THE SW N ATLC. THIS IS PRODUCING BROAD SCALE CONFLUENT FLOW ALOFT AND LEADING TO SUBSIDENCE ACROSS ALL BUT THE FAR ERN CARIBBEAN. AT THE SURFACE...THE 1031 MB HIGH PRES MENTIONED ABOVE ACROSS THE CENTRAL APPALACHIANS IS REINFORCING THE W FLANK OF THE WEAKENED ATLC RIDGE...AND PRODUCING A TIGHT PRES GRADIENT AND FRESH TO STRONG NE TO E TRADEWINDS ACROSS THE CARIBBEAN. THE PRES GRADIENT BETWEEN HIGH PRES ALONG THE EASTERN SEABOARD AND SEMI-PERMANENT LOW PRES OVER COLOMBIA HAS ENHANCED TRADEWIND FLOW ACROSS THE BASIN...WITH A BROAD ZONE OF 20-25 KT TRADES FOUND S OF 18N AND E OF 82W...WHILE THE TYPICALLY STRONG TRADES OFF THE COAST OF COLOMBIA CONTINUE AT GALE FORCE. AREAS OF LOW LEVEL MOISTURE EMBEDDED IN THIS ENHANCED LOW LEVEL FLOW WERE PRODUCING AN ELONGATED ZONE OF BROKEN TO OVERCAST LOW AND MID LEVEL CLOUDS WITH SCATTERED SHOWERS MOVING ACROSS THE SE CARIBBEAN...ACROSS THE EXTREME NE CARIBBEAN AND ADJACENT ISLANDS...AND DOWNSTREAM OF JAMAICA AND INLAND ACROSS HONDURAS...BELIZE...AND GUATEMALA. THESE STABLE CONDITIONS ALOFT LIMITED DIURNAL CONVECTION ACROSS THE GREATER ANTILLES TO JUST ISOLATED MODERATE TOPPED CELLS. EXPECT LITTLE CHANGE IN THIS OVERALL PATTERN DURING THE NEXT 24 HOURS. THE ATLANTIC OCEAN... A VERY PROGRESSIVE UPPER LEVEL PATTERN PREVAILS ACROSS THE ATLC THIS AFTERNOON...WITH A SHORTWAVE TROUGH GENERALLY N OF 20N AND ALONG 69W/70W...AND A SECOND WEAKER SHORTWAVE DOWNSTREAM N OF 18N AND ALONG 42W. AN OLD COLD FRONT HAS TRAVERSED MUCH OF THE ATLC BASIN AND WAS ACROSS THE ERN ATLC...ENTERING THE DISCUSSION AREA NEAR 31N31W AND EXTENDING W-SW TO NEAR 26N50W AND CONTINUED W TO NEAR 67W. SCATTERED TO LOCALLY NUMEROUS SHOWERS WERE NOTED ALONG AND WITHIN 30 NM N OF THE FRONT...WHILE NUMEROUS WELL DEFINED LLVL VORTICES COULD BE SEEN ALONG THIS LINGERING BOUNDARY BETWEEN 40W AND 60W...GENERATED BY HORIZONTAL SHEAR TO THE N. THE WEAK ATLC SURFACE RIDGE WAS CENTERED ON A 1026 MB HIGH NEAR 35N44W AND EXTENDED W-SW TO NEAR THE FLORIDA ATLC COASTAL WATERS...WHERE A N-S ALIGNED SURFACE TROUGH CONTINUED ALONG 79W/80W. ILL DEFINED REMNANTS OF THE W END OF THE FRONT COULD BE SEEN IN THE FORM OF CLUSTERS OF LOW AND MID CLOUDS AND EMBEDDED SHOWERS MOVING W ACROSS THE NW BAHAMAS. FARTHER E...AN UPPER LEVEL RIDGE WAS CENTERED OVER W TROPICAL AFRICA... SANDWICHED BETWEEN ELY FLOW ALOFT S OF 10N...AND SW FLOW ALOFT N OF 10N AND E OF 35W. AT THE SURFACE...THE 1026 MB HIGH IS PRODUCING A MODERATE PRES GRADIENT TO THE S ACROSS THE CENTRAL AND E TROPICAL ATLC...YIELDING A BROAD ZONE OF FRESH TRADES GENERALLY BETWEEN 10N AND 20N. THE MOST RECENT OUTBREAK OF SAL AND EMBEDDED DUST CAN STILL BE DETECTED IN SATELLITE IMAGERY FROM THE W AFRICAN COAST NEAR 14N...W-SW TO NEAR 06N44W. JUST TO THE W OF THIS...A MID LEVEL TROUGH AXIS INTERACTED WITH THE ITCZ IN THE PAST 48 HOURS TO AID IN PRODUCING A LARGE AREA OF TROPICAL MOISTURE S OF 13N BETWEEN 45W AND 56W...WHERE SCATTERED SHOWERS ARE OCCURRING BETWEEN 07N AND 14N...AND SCATTERED TO LOCALLY NUMEROUS TSTMS ARE OCCURRING BETWEEN 07N AND THE ITCZ. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ STRIPLING