000 AXNT20 KNHC 122340 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT TUE MAY 12 2009 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...METEOROLOGICAL ANALYSIS...WEATHER OBSERVATIONS...AND RADAR. BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...THE ITCZ... THE ITCZ AXIS IS CENTERED ALONG 8N13W 4N20W 1N32W CROSSING THE EQUATOR NEAR 40W EXTENDING TO NE BRAZIL NEAR 1S47W. NO SIGNIFICANT AREA OF CONVECTION ARE NOTED ON SATELLITE IMAGERY. HOWEVER...RECENT SATELLITE IMAGERY AND GLOBAL MODEL DATA DEPICTS ENHANCED CYCLONIC VORTICITY IN THE VICINITY OF A SURFACE TROUGH INLAND ACROSS W AFRICA FROM 19N9W TO A 1009 MB LOW NEAR 10N12W. SCATTERED MODERATE CONVECTION REMAINS WELL E OF THE SURFACE TROUGH OVER SW MALI AND IS MOST LIKELY ASSOCIATED WITH A WEAK TROPICAL WAVE. ...DISCUSSION... GULF OF MEXICO... AS OF 2100 UTC...A MIDDLE TO UPPER LEVEL SHORTWAVE TROUGH IS ACROSS THE NE GULF AND NRN FLORIDA WHICH IS SUPPORTING WEAK SURFACE TROUGHING EXTENDING FROM THE W ATLC ACROSS THE CENTRAL FLORIDA PENINSULA INTO THE SE GULF DELINEATED BY A STATIONARY FRONT FROM MELBOURNE FLORIDA INTO A 1014 MB LOW NEAR PORT CHARLOTTE. A SURFACE TROUGH EXTENDS S FROM THIS LOW ALONG THE SWRN FLORIDA COAST TO WITHIN 15/30 NM E OF KEY WEST. LOW-LEVEL CONVERGENCE ALONG AND NEAR THESE BOUNDARIES IS GENERATING SCATTERED SHOWERS AND TSTMS ACROSS THE FLORIDA PENINSULA. A STATIONARY FRONT IS ALSO DRAPED ACROSS THE FLORIDA PANHANDLE WITH SCATTERED SHOWERS AND ISOLATED TSTMS ALONG THE NRN GULF COAST FROM APALACHICOLA BAY WWD TO ERN LOUISIANA. ELSEWHERE ACROSS THE GULF...A WEAK SURFACE RIDGE OF HIGH PRESSURE EXTENDS FROM THE N/CENTRAL GULF SW TO TUXPAN MEXICO. E TO SE WINDS OF 10-15 KT ARE OBSERVED ACROSS THE CENTRAL AND WRN GULF WITH WINDS REACHING 20 KT ALONG THE S TEXAS COAST. CARIBBEAN SEA... BROAD RIDGING ALOFT COVERS THE CENTRAL AND ERN CARIBBEAN...WITH UPPER LEVEL DIFFLUENCE BETWEEN THE CARIBBEAN RIDGE...AND A TROUGH OVER THE NW CARIBBEAN AND EPAC...SUPPORTING SCATTERED SHOWERS AND TSTMS ACROSS THE SW CARIBBEAN S OF 12N INCLUDING ADJACENT PORTIONS OF PANAMA AND COSTA RICA IN THE VICINITY OF A 1008 MB LOW CENTERED OVER WRN PANAMA. HOWEVER...SUBSTANTIALLY MORE CONVECTIVE ACTIVITY IS FOUND OVER THE NEARBY E PACIFIC WATERS SW OF PANAMA AND COSTA RICA...WHERE LOW-LEVEL CONVERGENCE ALONG THE ITCZ IS AN ENHANCING MECHANISM. MEANWHILE...SURFACE HIGH PRESSURE N OF THE CARIBBEAN SEA IS RESULTING IN FRESH ELY TRADE WINDS THAT ARE FORECAST TO PERSIST THROUGH THE WEEK. THE STRONGEST WINDS ARE FOUND NEAR THE COAST OF COLOMBIA...WHERE E TO NE 20-25 KT WINDS ARE OCCURRING. POCKETS OF LOW LEVEL MOISTURE AND ISOLATED SHOWERS ARE BEING ADVECTED WESTWARD ACROSS THE CARIBBEAN...WITH THE GREATEST CONCENTRATION OF THESE SHOWERS WITHIN 200 NM EITHER SIDE OF A SURFACE TROUGH OVER THE NE CARIBBEAN THAT EXTENDS FROM 15N64W TO N OF ERN PUERTO RICO NEAR 20N66W. SURFACE OBSERVATIONS OVER SAINT CROIX...THE U.S. VIRGIN ISLANDS...AND ERN PUERTO RICO CONTINUE TO INDICATE A WEAK CYCLONIC WIND SHIFT ALONG THE TROUGH AXIS. ACROSS THE NW CARIBBEAN...DEEP LAYER DRY AIR IS RESULTING IN GENERALLY FAIR WEATHER CONDITIONS. ATLANTIC OCEAN... A SURFACE RIDGE ASSOCIATED WITH A 1026 MB SURFACE HIGH OVER THE CENTRAL ATLC NEAR 31N41W IS AFFECTING MUCH OF THE ATLC PORTION OF THE DISCUSSION AREA WITH OVERALL SUBSIDENCE AND GENERALLY FAIR WEATHER CONDITIONS OBSERVED. HOWEVER...POCKETS OF LOW LEVEL MOISTURE WITH ISOLATED SHOWERS ARE MOVING W ACROSS PORTIONS OF THE TROPICAL N ATLC. THE GREATEST OF THESE SHOWERS IS ASSOCIATED WITH A SURFACE TROUGH ACROSS THE NE CARIBBEAN TO 20N66W AND THE SCATTERED SHOWERS MAINLY LOCATED WITHIN 120 NM OF A LINE FROM 15N59W TO 21N67W. ALSO...ATMOSPHERIC LIFT ASSOCIATED WITH A MIDDLE TO UPPER LEVEL VORTICITY MAXIMUM OVER THE W ATLC IS SUPPORTING A COLD FRONT FROM 32N67W TO 31N71W THEN CONTINUING AS A STATIONARY FRONT INTO A 1018 MB SURFACE LOW NEAR 30N78W AND TO THE ERN FLORIDA PENINSULA COAST NEAR MELBOURNE. NE WINDS TO 20 KT ARE PRESENT N OF THE FRONT...AND WILL LIKELY INCREASE ACROSS THE N SEMICIRCLE OF THE LOW DURING THE NEXT DAY AS IT TRACKS NW TOWARD THE SURFACE RIDGE AXIS. LOW LEVEL CONVERGENCE IS SUPPORTING SCATTERED SHOWERS AND ISOLATED TSTMS ALONG AND WITHIN 90 NM OF THE FRONTAL BOUNDARY. ACROSS THE TROPICAL ATLC...AN UPPER LEVEL RIDGE IS PRESENT WITH AN AXIS EXTENDING FROM 11N20W TO 3N50W WITH AN UPPER HIGH CENTERED NEAR 5N33W. ASSOCIATED UPPER LEVEL DIVERGENCE IS ENHANCING SCATTERED SHOWERS ALONG THE ITCZ. $$ HUFFMAN