000 AXNT20 KNHC 092347 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 705 PM EST FRI MAR 09 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 EXTENDS SW FROM THE AFRICAN COAST AT 09N13W TO 02N19W WHERE LOW LEVEL WINDS INDICATE A TRANSITION TO AN ITCZ WHICH IN TURN CONTINUES SW CROSSING THE EQUATOR AT 23W TO 03S30W...THEN THE ITCZ TURNS W TO THE COAST OF S AMERICA AT 03S42W. LOCALLY BROKEN LOW AND MID LEVEL CLOUDS...WITH A FEW TSTMS...ARE OBSERVED SE OF THE ITCZ AND NW OF A LINE FROM 01N11W TO 08S35W. CONVECTION IS ACTIVE ALONG THE MONSOON TROUGH AS IT CONTINUES E ALONG 08N ACROSS AFRICA BETWEEN 10W AND 06E. ...DISCUSSION... THE GULF OF MEXICO... AN UPPER ANTICYCLONE OVER THE E PACIFIC NEAR 10N100W RIDGES NE ACROSS THE SE GULF OF MEXICO...THE FLORIDA STRAITS AND ACROSS THE NW BAHAMAS. AN UPPER SHORTWAVE TROUGH HAS MOVED OVER THE NW GULF WITH THE ASSOCIATED SURFACE COLD FRONT CURRENTLY EXTENDING FROM THE FLORIDA PANHANDLE TO A FRONTAL WAVE DEVELOPING AT 28N94W...WITH THE COLD FRONT THEN CONTINUING S ALONG 96W TURNING W AND INLAND MEXICO AT 22N97W. BROKEN TO OVERCAST LOW CLOUDS... WITH WIDESPREAD LIGHT RAIN...ARE OBSERVED TO THE N OF THE SURFACE FRONT...WITH PATCHY FOG REPORTED THROUGHOUT THE TEXAS COASTAL BEND AREA OCCASIONALLY REDUCING VISIBILITY BELOW 3 SM. NORTHERLY WINDS HAVE DIMINISHED TO 20 TO 25 KT N OF THE FRONT. LIGHTNING DATA IS DETECTING TSTMS ALONG THE FRONTAL BOUNDARY OFFSHORE THE TEXAS COAST. DENSE UPPER MOISTURE IS INDICATED N OF 27N WHILE THE REMAINDER OF THE GULF IS MOSTLY CLEAR EXCEPT FOR SMALL AREAS OF CUMULUS. THE COLD FRONT IS EXPECTED TO SOON STALL AND DRIFT NW WHILE DISSIPATING ON THE NEXT COUPLE OF DAYS. THE CARIBBEAN SEA... A POSITIVE TILT UPPER TROUGH HAS ITS MEAN AXIS EXTENDING FROM HISPANIOLA TO PANAMA...AND IS ACCOMPANIED BY VERY DRY AIR ALOFT. HOWEVER...DENSE UPPER MOISTURE ORIGINATING FROM CONVECTION OVER S AMERICA IS ADVECTED NE ACROSS THE SE CARIBBEAN...TO THE SE OF OF A LINE FROM THE VIRGIN ISLANDS TO THE NW VENEZUELA. LOCALLY BROKEN LOW LEVEL CLOUDS...WITH BRIEF SHOWERS...ARE RACING WESTWARD ACROSS THE CARIBBEAN IN EASTERLY 15 TO 20 KT TRADES... WITH THE EXCEPTION OF AN AREA OF CLEAR SKIES OBSERVED WITHIN 120 NM OF THE NW COLOMBIAN COAST WHERE LOW LEVEL WINDS ARE NE TO E AT 25 TO 30 KT. THE ATLANTIC OCEAN... AN UPPER RIDGE IS ORIENTATED SW TO NE FROM THE FLORIDA STRAITS TO BEYOND BERMUDA. DENSE UPPER MOISTURE IS OBSERVED W OF THIS RIDGE AXIS...AND IS PROGRESSING E WITH TIME. AN UPPER CYCLONE IS CENTERED NEAR 33N62W WITH AN UPPER TROUGH EXTENDING SW THROUGH ANOTHER UPPER CYCLONE AT 27N66W...WITH THE TROUGH CONTINUING SW ACROSS HISPANIOLA TO THE SW CARIBBEAN. THE UPPER LEVELS APPEAR VERY DRY E OF THE PREVIOUSLY MENTIONED UPPER RIDGE...AND THIS DOWNSTREAM TROUGH. AT THE LOW LEVELS A RIDGE EXTENDS FROM 32N60W TO CENTRAL FLORIDA WITH LOCALLY BROKEN TRADE WIND CUMULUS MOVING FROM SE TO NW THROUGH THE RIDGE. UPPER DIFFLUENCE E OF THE UPPER TROUGH IS ENHANCING CONVECTION UNDER A BROAD UPPER RIDGE THAT COVERS THE DISCUSSION AREA BETWEEN 40W AND 60W...IN THE AREA FROM 23N TO 30N BETWEEN 50W AND 63W WITH A LOW LEVEL TROUGH INDUCED FROM 23N63W TO 29N62W. LIGHTNING DATA DETECTS TSTMS FIRING OFF WITHIN 150 NM E OF THIS LOW LEVEL TROUGH. A SURFACE COLD FRONT ENTERS THE AREA AT 32N27N BUT IMMEDIATELY WEAKENS TO A SHEAR AXIS AS IT CONTINUES W GRADUALLY DISSIPATING ALONG 24N BETWEEN 40W AND 50W. A SLIGHTLY NEGATIVE TILT UPPER TROUGH EXTENDS FROM 32N30W TO A BASE AT 22N29W WHILE A SECOND UPPER TROUGH IS OVER AFRICA TO THE N OF 16N. A NARROW UPPER RIDGE IS SQUEEZED BETWEEN THESE TROUGHS AND IS ACCOMPANIED BY UPPER MOISTURE WHICH IS NOW MOVING OVER THE W AFRICAN COAST TO THE N OF 10N. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ NELSON