000 AXNT20 KNHC 230613 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 105 AM EST SAT FEB 23 2008 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN SECTIONS OF SOUTH AMERICA...AND THE ATLANTIC OCEAN TO THE AFRICAN COAST FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON SATELLITE IMAGERY...METEOROLOGICAL ANALYSIS... WEATHER OBSERVATIONS...AND RADAR. BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0545 UTC ...ITCZ... ITCZ AXIS IS CENTERED ALONG 5N10W 3N15W 3N34W 1N45W. SCATTERED MODERATE ISOLATED STRONG CONVECTION NOTED WITHIN 240 NM N OF THE ITCZ AXIS BETWEEN 16W AND 25W. ISOLATED MODERATE OBSERVED S OF 5N BETWEEN 40W AND 50W. ...DISCUSSION... GULF OF MEXICO... AN UPPER TROUGH IS OVER THE WESTERN GULF ATTM ACCOMPANIED BY DRY UPPER AIR GENERALLY W OF A LINE FROM 30N87W TO 20N97W. AN UPPER ANTICYCLONE OVER THE N CENTRAL CARIBBEAN RIDGES NW OVER THE GULF OF MEXICO ALONG POINTS 20N95W 27N88W 30N86W. UPPER LEVEL MOISTURE...ORIGINATING FROM FORMER CONVECTION OVER THE E PACIFIC NEAR 15N95W AND OVER CENTRAL AMERICA BETWEEN 85W AND 95W...IS STREAMING NE UNDER THIS RIDGE. AT 03 UTC A SURFACE COLD FRONT EXTENDS FROM EXTREME W FLORIDA SW TO THE WESTERN BAY OF CAMPECHE THEN TURNS NW BACKING UP AGAINST THE MEXICAN MOUNTAINS FROM 20N98W TO S TEXAS NEAR 26N98W THEN LOSES IDENTITY. UPPER DIFFLUENCE E OF THE THE UPPER TROUGH IS STILL ENHANCING CONVECTION AHEAD OF THE SURFACE FRONT ALONG LINE FROM 27N88W TO BEYOND 30N85W WITH LIGHTNING DATA STILL REGISTERING HITS ALONG THIS LINE. A 90 NM WIDE BAND OF OVERCAST LOW CLOUDS...AND VISIBILITIES ESTIMATED IN THE 3-5 NM RANGE IN FOG...IS NOTED FROM LOUISIANA TO THE SE TEXAS/NE OLD MEXICO BORDER. E OF THE FRONT...THE ATLC SUBTROPICAL RIDGE EXTENDS W OVER THE AREA WITH ITS AXIS ALONG 24N TO NEAR 90W. CARIBBEAN... AN UPPER ANTICYCLONE IS CENTERED NEAR 18N75W WITH ITS ENVELOPE DOMINATING THE CARIBBEAN W OF 67W. THE WESTERN PORTION OF A CENTRAL ATLC UPPER TROUGH STILL EXTENDS INTO THE EASTERN CARIBBEAN BUT APPEARS TO BE FILLING WITH TIME. THIN BROKEN CIRRIFORM CLOUDS ARE NOTED OVER THE NW CARIBBEAN ALONG THE UPPER RIDGE. DRY UPPER AIR IS INDICATED ELSEWHERE ALOFT. AT THE LOW LEVELS THE ATLC SUBTROPICAL RIDGE EXTENDS W ACROSS THE NW CARIBBEAN WITH ITS AXIS ROUGHLY JUST N OF THE AREA ALONG 24N. LOCALLY BROKEN LOW TRADE WINDS CLOUDS WITH EMBEDDED SHOWERS ARE NOTED WITHIN 90 NM EITHER SIDE OF LINE 12N61W 20N85W. ATLANTIC... AN UPPER ANTICYCLONE IS CENTERED OVER THE N CENTRAL CARIBBEAN NEAR 18N75W WITH A RIDGE EXTENDING NE ALONG 27N70W TO JUST BEYOND 34N60W. A MOISTURE PLUME IS NOTED ALONG THE RIDGE N OF POINTS 23N80W 27N70W 25N55W. THE CENTRAL SUBTROPICAL ATLC IS DOMINATED ALOFT BY AN UPPER TROUGH EXTENDING THROUGH CYCLONES ALONG 35N14W 21N40W 15N55W. DRY UPPER AIR IS NOTED OVER THE SW SEMICIRCLES OF EACH OF THESE CYCLONES. SHOWERS ARE ENHANCED NE OF THE CYCLONE AT 21N40W. THE TROPICAL E ATLC IS DOMINATED ALOFT BY AN ANTICYCLONE AT 6N18W WITH A RIDGE EXTENDING W TO NEAR 4N45W. UPPER DIFFLUENCE ALONG THIS RIDGE AXIS IS ENHANCING CONVECTION NEAR 5N20W WITH THE DEBRIS MOISTURE SPREADING N TO ALONG 21N BETWEEN 19W AND 34W. A WELL DEFINED 300 NM WIDE MOISTURE PLUME...ORIGINATING FROM CONVECTION OVER S AMERICA NEAR 2S50W...STREAMS NE ALONG THE TROPICAL UPPER RIDGE...ROUGHLY ALONG 3N48W 15N35W 21N26W...THEN TURNS E ACROSS AFRICA ALONG 24N13W 30N8W. AT THE LOW LEVELS A HIGH PRES IS AT 34N36W 1030 MB WITH A RIDGE SW THROUGH THE STRAITS OF FLORIDA. A SURFACE FRONT HAS STALLED JUST OFFSHORE THE GEORGIA COAST WITH SHOWERS AND A FEW TSTMS VERIFIED BY LIGHTNING DATA ALONG LINE 28N79W 33N75W. LOCALLY BROKEN STRATOCUMULUS IS MOVING ANTICYCLONICALLY ACROSS THE WATERS SE OF THE LOW LEVEL RIDGE. $$ NELSON