000 AXNT20 KNHC 080007 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 705 PM EST WED MAR 07 2012 CORRECTED FOR PRECIPITATION INFORMATION IN NORTHWESTERN COLOMBIA NEAR THE PANAMA BORDER...AND FOR THE ATLANTIC OCEAN SECTION 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 07N11W TO 01N14W WHERE LOW LEVEL WINDS INDICATE A TRANSITION TO AN ITCZ WHICH CONTINUES W ALONG THE EQUATOR TO 40W THEN TURNS SW TO THE COAST OF S AMERICA AT 02S44W. ISOLATED MODERATE AND STRONG CONVECTION IS NOTED N OF THE EQUATOR E OF 01W AND WITHIN 60 NM OF THE ITCZ BETWEEN 24N AND 44W. LOCALLY BROKEN LOW AND MID LEVEL CLOUDS WITH EMBEDDED SHOWERS ARE OBSERVED FROM 02N TO 07N BETWEEN 07W AND 17W. ...DISCUSSION... THE GULF OF MEXICO... AN UPPER ANTICYCLONE IS OVER THE E PACIFIC AT 15N97W...WITH AN UPPER RIDGE EXTENDING N ACROSS CENTRAL AMERICA AND THE GULF OF MEXICO...AND CONTINUING NE ALONG THE EASTERN SEABOARD OF THE CONUS. SOME UPPER MOISTURE WAS ADVECTED E ACROSS THE RIDGE AXIS...AND IS NOW SPILLING SE OVER THE FLORIDA BIG BEND AREA IN THE FORM OF THIN BROKEN MID AND UPPER LEVEL CLOUDS. SOME THIN SCATTERED CIRRIFORM CLOUDS ARE RACING NE OVER THE BAY OF CAMPECHE. OTHERWISE...THE UPPER LEVELS APPEAR VERY DRY ACROSS THE GULF OF MEXICO. AT THE LOW LEVELS A RIDGE DISSECTS THE GULF FROM NW FLORIDA TO THE BAY OF CAMPECHE. LOCALLY BROKEN LOW LEVEL CLOUDS...ORIGINALLY ASSOCIATED WITH A DISSIPATING FRONT...ARE NOW MOVING N OVER THE E CENTRAL GULF WATERS. AN AREA OF LOCALLY OVERCAST LOW LEVEL CLOUDS...AND PATCHY FOG REDUCING VISIBILITIES TO 3 SM...IS MOVING N IN THE LOW LEVEL SOUTHERLY FLOW OVER THE NW GULF...AND EXTEND INLAND OVER THE NE TEXAS AND SW LOUISIANA COASTAL PLAINS. THE SURFACE RIDGE IS EXPECTED TO WEAKEN AND SHIFT EASTWARD OVER THE NEXT COUPLE OF DAYS...WITH THE SOUTHERLY WINDS DIMINISHING SOMEWHAT. THE NEXT COLD FRONT WILL MOVE INTO THE NEW WATERS ON FRI ACCOMPANIED BY NORTHERLY WINDS TO 30 KT. THE CARIBBEAN SEA... AN UPPER TROUGH HAS AMPLIFIED S OVER THE ENTIRE W CARIBBEAN AND IS ACCOMPANIED BY VERY DRY AIR ALOFT. AN UPPER RIDGE EXTENDS N FROM S AMERICA OVER THE E CARIBBEAN RESULTING ZONAL FLOW ALOFT...WHICH ALSO APPEARS QUITE DRY. THE POST FRONTAL SHEAR LINES OVER THE N CENTRAL AND NW CARIBBEAN HAVE FURTHER WEAKENED TO BANDS OF LOCALLY BROKEN LOW LEVEL CLOUDS RACING WESTWARD OVER THE CARIBBEAN TO THE N OF 15N. THE DRY AIR ALOFT IS SUPPRESSING ASSOCIATED CONVECTION TO OROGRAPHICALLY INDUCED LIGHT SHOWERS OVER THE E PORTIONS OF THE LARGER ISLANDS. THE EASTERLY TRADES ARE ENHANCED ALONG THE NW COAST OF COLOMBIA WITH A 30 TO 35 KT GALE WARNING IN EFFECT FROM 11N TO 15N BETWEEN 73W AND 79W THIS AFTERNOON...BUT THE EFFECTED AREA IS FORECAST TO SHRINK FROM 11N TO 13N BETWEEN 73W AND 77W ON FRI...WITH THE ASSOCIATED SEAS TO 18 FT TONIGHT SUBSIDING TO ABOUT A 16 FT MAXIMUM ON FRI. THE ATLANTIC OCEAN... AN UPPER RIDGE IS SHIFTING E OVER THE DISCUSSION AREA W OF 77W AND IS IS ACCOMPANIED BY UPPER MOISTURE WHICH WILL MOVE S OVER THE NW BAHAMAS TONIGHT IN THE FORM OF BROKEN MID AND UPPER CLOUDS. IMMEDIATELY TO THE E...AN UPPER TROUGH HAS ITS MEAN AXIS EXTENDING FROM BERMUDA TO E CUBA AND IS CONTINUING E WITH TIME ACCOMPANIED BY DRY UPPER AIR WITHIN 300 NM W OF ITS AXIS. AN UPPER ANTICYCLONE HAS DEVELOPED ALONG AN UPPER RIDGE NEAR 20N63W...WITH THE UPPER RIDGE CONTINUING ENE TO A UNSTABLE CREST COLLAPSING SE NEAR 25N48W. A NARROW BAND OF UPPER MOISTURE IS STREAMING NE ALONG THE NW PERIPHERY OF THIS RIDGE...ROUGHLY WITHIN 120 NM EITHER SIDE OF A LINE FROM 27N67W TO 30N48W TO BEYOND 33N43W. A MID TO UPPER LEVEL CYCLONE HAS CUT OFF OVER THE CENTRAL ATLANTIC AT 30N35W...WITH A TROUGH EXTENDING SW TO AN UPPER CYCLONE RAPIDLY FILLING AT 16N57W. THE ASSOCIATED SURFACE LOW HAS WEAKENED TO AN OPEN TROUGH EXTENDING S TO N FROM 23N41W TO 31N39W. LOW AND MID LEVEL CLOUDS AND CONVECTION IS OBSERVED WITHIN 420 NM OVER THE E SEMICIRCLE OF THE PARENT UPPER CYCLONE WITH THE RESULTANT DEBRIS MOISTURE SPREADING N WITH TIME. DRY UPPER AIR IS INDICATED ALONG THE COLLAPSING RIDGE...AND ALSO ALONG THE UPPER TROUGH...AND IS NOW ENTRAINING INTO THE W SEMICIRCLE OF THE CUT OFF CYCLONE AT 30N35W. AN UPPER TROUGH IS SHIFTING S OVER NW AFRICA WITH ITS BASE NEAR 22N05W AT THE MOMENT. A BROAD UPPER RIDGE DOMINATES THE SE PORTION OF THE N ATLANTIC WITH A VERY DENSE MOISTURE PLUME... ORIGINATING OVER S AMERICA...STREAMING NE ALONG THE NW PERIPHERY OF RIDGE...ALL WITHIN 270 NM EITHER SIDE OF A LINE FROM 05N55W TO 20N30W...THEN TURNING E ACROSS AFRICA TO THE S OF THE DIGGING TROUGH JUST MENTIONED. ELSEWHERE AT THE LOW LEVELS...A SHEAR AXIS EXTENDS FROM 31N48W TO 25N65W TO 25N72W AND IS ACCOMPANIED BY LOCALLY OVERCAST LOW AND MID LEVELS CLOUDS AND EMBEDDED SHOWERS WITHIN 90 NM EITHER SIDE OF ITS AXIS. TO THE N OF THIS DENSE CLOUDINESS IS LOCALLY BROKEN COLD AIR STRATOCUMULUS CLOUDS OBSERVED TO THE E COAST OF THE CONUS. THE SHEAR AXIS SHOULD GRADUALLY DISSIPATE OVER THE NEXT DAY OR SO. 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