000 AXNT20 KNHC 132346 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT WED MAY 13 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. ...TROPICAL WAVES... A TROPICAL WAVE IS ALONG 19W S OF 12N MOVING W NEAR 15 KT. ALTHOUGH THE WAVE DOES NOT EXHIBIT AN OVERLY IMPRESSIVE SATELLITE PRESENTATION...RECENT GLOBAL MODEL DATA INDICATES SURFACE TO 700 MB WINDS VEERING FROM NE TO SE IN CONJUNCTION WITH THE WAVE AXIS AND COINCIDING WITH A WESTWARD-MOVING DEEP LAYER MOISTURE MAXIMUM AS INDICATED IN THE MIMIC TPW PRODUCT FROM CIMSS. DESPITE THE TEMPORARY LOSS OF SIGNIFICANT CONVECTION WHILE EMBEDDED WITHIN AFRICAN DUST ON THE NRN EXTENT OF THE WAVE...REGIONAL VARIATIONS IN WIND SPEED AT THE SURFACE ARE MAINTAINING POSITIVE SURFACE VORTICITY NEAR THE WAVE. ONLY SCATTERED SHOWERS ACCOMPANY THE WAVE ALONG THE ITCZ AXIS FROM 2N-5N BETWEEN 16W-21W. ...ITCZ... THE ITCZ AXIS IS CENTERED ALONG 4N20W 1N27W CROSSING THE EQUATOR NEAR 35W EXTENDING TO NE BRAZIL NEAR 1S47W. ISOLATED MODERATE CONVECTION IS S OF 2N BETWEEN 40W-44W. ...DISCUSSION... GULF OF MEXICO... AN UPPER RIDGE OVER THE WRN GULF IS ADVECTING TROPICAL MOISTURE FROM THE PACIFIC INTO THE NW GULF W OF 87W. THIS MOISTURE IS RESULTING IN MIDDLE TO HIGH LEVEL CLOUDINESS. AS OF 2100 UTC... A SURFACE TROUGH EXTENDS ACROSS THE CENTRAL FLORIDA PENINSULA WITH LOW-LEVEL CONVERGENCE AND DAYTIME HEATING DRIVEN BY MOIST E-SE SURFACE FLOW SUPPORTING SCATTERED SHOWERS AND TSTMS ACROSS MUCH OF THE WRN HALF OF THE PENINSULA AND ALONG THE IMMEDIATE FLORIDA PENINSULA GULF COAST. ELSEWHERE...MAINLY FAIR WEATHER DOMINATES THE AREA WITH SHIP AND BUOY OBSERVATIONS INDICATING STRONGER WINDS OF 15-20 KT OVER THE WRN WATERS...DUE TO THE TIGHTENED PRESSURE GRADIENT BETWEEN HIGH PRESSURE OFFSHORE OF THE NEW ENGLAND STATES AND BROAD TROUGHING ACROSS THE S/CENTRAL CONUS AND MEXICO. CARIBBEAN SEA... BROAD RIDGING ALOFT COVERS THE ERN CARIBBEAN E OF 75W. UPPER LEVEL DIFFLUENCE BETWEEN THE RIDGE AND A TROUGH OVER THE NW CARIBBEAN IS SUPPORTING SCATTERED SHOWERS AND TSTMS ACROSS THE SW CARIBBEAN S OF 12N...INCLUDING ADJACENT PORTIONS OF PANAMA... COSTA RICA AND NRN COLOMBIA. MEANWHILE...SURFACE HIGH PRESSURE N OF THE CARIBBEAN SEA IS RESULTING IN FRESH ELY TRADE WINDS WHICH ARE FORECAST TO PERSIST THROUGH THE WEEK. POCKETS OF LOW-LEVEL MOISTURE AND ISOLATED SHOWERS ARE BEING ADVECTED W ACROSS THE CARIBBEAN...WITH THE GREATEST CONCENTRATION OF THESE SHOWERS FOCUSED NEAR A SURFACE TROUGH EXTENDING FROM THE W ATLC NEAR 23N69W ACROSS HISPANIOLA TO 17N72W. BROAD CYCLONIC TURNING OF THE WIND IS NOTED IN THE VICINITY OF THIS TROUGH WITH SCATTERED SHOWERS AND ISOLATED TSTMS N OF 17N AND E OF 73W. ACROSS THE NW CARIBBEAN...DEEP LAYER DRY AIR IS RESULTING IN GENERALLY FAIR WEATHER CONDITIONS AS NW FLOW ALOFT DOMINATES. DURING THE NEXT FEW DAYS...THE TRADE WINDS WILL GRADUALLY DIMINISH AS THE SURFACE HIGH OVER THE CENTRAL ATLC MOVES NE AND A BROAD SURFACE TROUGH DEVELOPS OVER THE ERN GULF OF MEXICO THIS WEEKEND. ATLANTIC OCEAN... A SURFACE RIDGE ASSOCIATED WITH A 1029 MB SURFACE HIGH OVER THE CENTRAL ATLC NEAR 34N31W IS AFFECTING MUCH OF THE ATLC PORTION OF THE DISCUSSION AREA WITH OVERALL SUBSIDENCE AND GENERALLY FAIR WEATHER CONDITIONS RESULTING. HOWEVER...POCKETS OF LOW LEVEL MOISTURE WITH ISOLATED SHOWERS ARE MOVING W ACROSS PORTIONS OF THE SW AND TROPICAL N ATLC. THE LARGEST FOCUS OF THESE SHOWERS IS ASSOCIATED WITH A SURFACE TROUGH EXTENDING ACROSS HISPANIOLA TO 23N69W AND IS GENERATING SCATTERED SHOWERS FROM 17N-23N BETWEEN 61W-72W. THIS TROUGH IS FORECAST TO CONTINUE MOVING W NEAR 15 KT AS IT AFFECTS THE GREATER ANTILLES DURING THE NEXT FEW DAYS. ALSO...ATMOSPHERIC LIFT ASSOCIATED WITH A MID/UPPER-LEVEL TROUGH OVER THE W ATLC IS SUPPORTING A COLD FRONT FROM 32N57W TO 30N68W WITH A STATIONARY FRONT CONTINUING ALONG 30N75W 32N80W AND INLAND OVER SRN GEORGIA. LOW LEVEL CONVERGENCE IS SUPPORTING SCATTERED SHOWERS ALONG AND WITHIN 90 NM EITHER SIDE OF THE FRONTAL BOUNDARY. ACROSS THE TROPICAL ATLC...AN UPPER LEVEL RIDGE IS PRESENT WITH AN AXIS EXTENDING FROM 12N13W TO 2N44W WITH AN UPPER HIGH CENTERED NEAR 10N25W. $$ HUFFMAN