000 AXNT20 KNHC 132347 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 705 PM EST TUE NOV 13 2007 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 80W S OF 17N MOVING W NEAR 20 KT. THE MIMIC TPW ANIMATION SHOWS THE WEAK MOISTURE SURGE RELATED TO THIS WAVE MOVING INTO THE AREA OF DISTURBED WEATHER IN THE SW CARIBBEAN...POSSIBLY ENHANCING IT SOME. DUE TO THE WIDESPREAD DEEP CLOUDINESS ITS DIFFICULT TO TELL EXACTLY WHERE THE WAVE IS LOCATED. FOR DETAILS REFER TO THE CARIBBEAN SECTION BELOW. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 8N13W 6N24W 7N37W 7N45W 4N53W. SCATTERED MODERATE CONVECTION IS FROM 8N-11N BETWEEN 41W-43W. DISCUSSION... GULF OF MEXICO... WEAKENING HIGH PRES...ANALYZED 1020 MB...IS CENTERED ABOUT 100 NM S OF MOBILE ALABAMA NEAR 29N87W. THIS HAS ALLOWED WINDS TO WEAKEN ACROSS THE NRN HALF OF THE GULF BUT REMAIN MODERATE ACROSS THE SRN PART. SAT IMAGERY SHOWS BROKEN CLOUDINESS WITH POSSIBLE ISOLATED SHALLOW SHOWERS HOVERING OVER THE BAY OF CAMPECHE...ASSOCIATED WITH LOW-LEVEL TROUGHING IN THE W CARIBBEAN. SIMILAR CLOUDINESS AND ISOLATED SHOWERS ARE OVER SE FLORIDA STREAMING IN FROM A WEAK SFC TROUGH IN THE BAHAMAS. ALOFT...A MID TO UPPER LEVEL RIDGE HAS BUILT NWD INTO THE SW GULF WHILE A SERIES OF UPPER SHORTWAVES PROPAGATE THROUGH THE EXTREME NE PORTION. CURRENTLY...A WELL DEFINED SHORTWAVE EXTENDS FROM THE MID-ATLANTIC TO THE MISSISSIPPI VALLEY. ABUNDANT SUBSIDENCE LIES OVER THE BULK OF THE REGION...MOST PRONOUNCED FROM 22N-26N W OF 83W. LOOKING AHEAD...SFC HIGH PRES IS ANTICIPATED TO WEAKEN FURTHER AND RETREAT EWD AS A COLD FRONT MOVES INTO THE NW PORTION LATE WED/EARLY THU. CARIBBEAN SEA... CLUSTERS OF SCATTERED MODERATE CONVECTION HAVE BEEN PERSISTING OVER THE LAST SEVERAL HOURS IN THE SW CARIB...ROUGHLY S OF 13N W OF 78W. THE PRIMARY TRIGGER FOR THE ACTIVITY APPEARS TO BE DIFFLUENCE ALONG A STRETCHED MID TO UPPER RIDGE AXIS. A WEAK LOW LATITUDE TROPICAL WAVE HAS TRACKED INTO THIS REGION AND MAY ALSO BE PROVIDING SOME SUPPORT. FARTHER NW...A WEAK LOW-LEVEL TROUGH LIES ALONG 87W FROM 15N-20N PRODUCING SCATTERED SHOWERS AND ISOLATED TSTMS WITHIN 180 NM OF THE AXIS. THE TAIL END OF A CENTRAL ATLC SFC TROUGH RUNS ACROSS PUERTO RICO AND HISPANIOLA PRODUCING SCATTERED SHOWERS AND ISOLATED TSTMS OVER THE ISLANDS AND SURROUNDING WATERS. THE REMAINDER OF THE AREA IS RATHER TRANQUIL UNDER MODERATE TO FRESH TRADE WIND FLOW AND STABLE MID AND UPPER LEVEL AIR ADVECTED BY FAIRLY ZONAL UPPER FLOW. ATLANTIC OCEAN... MODERATE SFC SUBTROPICAL RIDGING DOMINATES THE SW ATLC PRODUCING NE TO ELY LOW-LEVEL FLOW ACROSS THE AREA. THE FLOW IS STRONGEST JUST E OF A WEAK LOW-LEVEL PERTURBATION IN THE NW BAHAMAS. THE BRISK WINDS ARE GENERATING ENOUGH INSTABILITY TO STIR UP AND STEER STREAMS OF LOW CLOUDS AND QUICK MOVING SHALLOW SHOWERS WHICH ARE ENHANCED OVER THE BAHAMAS AND SE FLA NEAR THE AFOREMENTIONED SFC TROUGH. ALOFT...A SERIES OF WEAK SHORTWAVES ARE PROPAGATING THROUGH A LARGE TROUGH SHARPENING IT IN SPOTS. THE OVERALL BROAD TROUGH REACHES A BASE NEAR THE NRN LEEWARD ISLANDS. THIS UPPER SYSTEM IS SUPPORTING A LINGERING STRETCHED OUT OLD FRONTAL TROUGH ANALYZED ALONG 32N43W 22N54W TO PUERTO RICO. LOW-LEVEL CONVERGENCE NEAR THE TROUGH COUPLED WITH EXTENSIVE MID AND UPPER LEVEL SWLY FLOW IS PRODUCING SCATTERED SHOWERS AND TSTMS FROM 23N-27N BETWEEN 46W-50W. ISOLATED TO SCATTERED ACTIVITY IS ELSEWHERE WITHIN 150 NM OF THE BOUNDARY. THE REMAINDER OF THE CENTRAL AND E ATLC IS UNDER A WEAK SFC PRES PATTERN CONSISTING OF A NEARLY STATIONARY 1020 MB HIGH NEAR 27N30W AND A 1012 MB LOW JUST N OF THE AZORES. THIS PATTERN IS ALLOWING WINDS TO BE LIGHT TO MODERATE ACROSS THE REGION. IN THE MID AND UPPER LEVELS...A BROAD RIDGE/TROUGH PATTERN IS IN PLACE. A SWLY JET ORIGINATES JUST E OF THE TROUGH BASE NEAR 12N30W AND EXTENDS NE TO AFRICA NEAR 17N16W. DIFFLUENCE TO THE SE OF THE JET IS PRODUCING ABUNDANT CLOUDINESS BUT NOT MUCH CONVECTION ALONG THE ITCZ...WHICH WAS THE CASE YESTERDAY. $$ CANGIALOSI