000 AXNT20 KNHC 091759 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT THU JUL 09 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. ...TROPICAL WAVES... A TROPICAL WAVE IS ALONG 24W S OF 15N MOVING W NEAR 18 KT. ALTHOUGH LACKING A DEFINED SATELLITE PRESENTATION DUE TO A LARGE AREA OF SAHARAN DUST ACROSS THE ERN TROPICAL ATLC...THIS WAVE TRACKED W OF DAKAR AROUND 07/1800 UTC...BASED ON THE UPPER AIR TIME SECTION ANALYSES THE PAST FEW DAYS FROM DAKAR SENEGAL. ALSO AN EARLIER SCATTEROMETER PASS AROUND 0800 UTC CONFIRMED THE WAVE REMAINS AT LOW-LATITUDE AND LARGELY EMBEDDED WITHIN THE ITCZ. SCATTERED MODERATE CONVECTION IS FROM 5N-13N BETWEEN 18W-22W AND FROM 5N-9N BETWEEN 22W-27W. A TROPICAL WAVE IS ALONG 52W S OF 20N MOVING W NEAR 15 KT. A LARGE AREA OF SAHARAN DUST SURROUNDS THE WAVE AND IS LIMITING ANY DEEP CONVECTION TO S OF 12N. AN EARLIER QUIKSCAT PASS AROUND 0930 UTC DEPICTED VERY BROAD CYCLONIC WIND FLOW IN THE VICINITY OF THE WAVE AXIS. CONFINED MOSTLY ALONG THE ITCZ AXIS...SCATTERED MODERATE CONVECTION IS FROM 8N-12N BETWEEN 51W-59W. A TROPICAL WAVE EXTENDS FROM THE CENTRAL BAY OF CAMPECHE NEAR 22N92W ACROSS THE ISTHMUS OF TEHUANTEPEC INTO THE E PACIFIC MOVING W NEAR 15 KT. THIS WAVE COINCIDES WITH AN AREA OF INCREASED PRECIPITABLE WATER ACROSS THE S/CENTRAL GULF OF MEXICO...YUCATAN PENINSULA AND A LARGE PORTION OF CENTRAL AMERICA. WHILE ONLY SCATTERED SHOWERS ARE FOUND IN THE BAY OF CAMPECHE NEAR THE WAVE AXIS...LOW-LEVEL SURFACE WIND CONVERGENCE AND OROGRAPHIC EFFECTS ACROSS THE HIGHER TERRAIN OF CENTRAL AMERICA ARE ENHANCING SCATTERED MODERATE/ISOLATED STRONG CONVECTION FROM 13N-21N BETWEEN 84W-90W. ...ITCZ... THE ITCZ AXIS IS CENTERED ALONG 12N16W 9N22W 7N26W 6N37W 9N51W 10N55W ACROSS NRN TRINIDAD TO 10N66W. SCATTERED MODERATE CONVECTION IS FROM 5N-13N BETWEEN 18W-22W AND FROM 5N-9N BETWEEN 22W-27W ASSOCIATED WITH THE TROPICAL WAVE ALONG 24W. SIMILAR CONVECTION IS W OF THE TROPICAL WAVE ALONG 52W FROM 8N-12N BETWEEN 51W-59W. ...DISCUSSION... GULF OF MEXICO... MOSTLY SE TO S SURFACE WINDS ARE OBSERVED ACROSS THE GULF OF MEXICO S OF 26N AS A RIDGE OF HIGH PRESSURE EXTENDS FROM THE W ATLC OVER SRN FLORIDA AND ALONG 25N TO 98W. N OF 26N...LOW-LEVEL CONVERGENCE IS CONCENTRATED ALONG A SURFACE TROUGH THAT EXTENDS FROM THE WRN FLORIDA PANHANDLE TO 29N90W IN THE N/CENTRAL GULF AND IS GENERATING SCATTERED SHOWERS AND TSTMS FROM 26N-30N E OF 92W OVER THE NE GULF AND ACROSS THE CENTRAL FLORIDA PENINSULA. AN UPPER LEVEL TROUGH IS PROGRESSING SLOWLY EWD ACROSS THE SE CONUS AND NE GULF WHICH IS ALSO ENHANCING THIS ACTIVITY. ELSEWHERE ACROSS THE REMAINDER OF THE GULF S OF 26N...MOSTLY FAIR SKIES PREVAIL...HOWEVER...A TROPICAL WAVE IS MOVING ACROSS THE BAY OF CAMPECHE AND SW GULF BRINGING INCREASED CLOUDINESS AND MOISTURE IN THE FORM OF ISOLATED SHOWERS S OF 21N. OTHER SCATTERED SHOWERS AND TSTMS ARE OCCURRING OVER THE YUCATAN PENINSULA BUT REMAINING MOSTLY OVER INTERIOR LOCATIONS. CARIBBEAN SEA... THE WWD EXTENT OF NELY FLOW ALOFT ON THE BACK SIDE OF AN UPPER LOW OVER THE CENTRAL CARIBBEAN CENTERED NEAR 16N75W IS GENERATING SCATTERED SHOWERS AND TSTMS ACROSS THE GULF OF HONDURAS...PORTIONS OF CENTRAL AMERICA N OF 14N AND THE YUCATAN PENINSULA. THE NELY FLOW ALOFT IS PROVIDING MOST OF THE NW AND CENTRAL CARIBBEAN WITH MODERATE TO STRONG SUBSIDENCE AND FAIR WEATHER CONDITIONS. HOWEVER...SCATTERED SHOWERS AND TSTMS ARE ACROSS THE SW CARIBBEAN AND ADJACENT COASTAL AREAS OF CENTRAL AMERICA FROM 8N-13N W OF 73W. SURFACE CONVERGENCE DUE TO THE PROXIMITY OF THE E PACIFIC ITCZ ALONG 8N IS ENHANCING THIS ACTIVITY. ACROSS THE ERN CARIBBEAN...A SURFACE TROUGH IS MOVING WESTWARD N OF PUERTO RICO OVER THE SW NORTH ATLC AND IS PROVIDING A FEW ISOLATED SHOWERS OVER THE ERN GREATER ANTILLES. ELSEWHERE OVER THE SE CARIBBEAN...AS THE TROPICAL WAVE ALONG 52W TRACKS CLOSER TO THE LESSER ANTILLES...INCREASED MOISTURE AND INSTABILITY IS NOTED ON SATELLITE IMAGERY AS SCATTERED SHOWERS AND ISOLATED TSTMS ARE OVER THE WINDWARD ISLANDS S OF 14N E OF 63W. FRESH TO STRONG ELY TRADE WIND FLOW CONTINUES ACROSS THE BASIN AND IS FORECAST TO PERSIST THROUGH THE WEEKEND. ATLANTIC OCEAN... SCATTERED SHOWERS AND ISOLATED TSTMS ARE ACROSS THE SW NORTH ATLC NW OF A LINE FROM MELBOURNE FLORIDA TO 32N73W. THIS ACTIVITY IS DRIVEN BY LOW-LEVEL CONVERGENCE ALONG AND S OF A FRONTAL BOUNDARY THAT IS POSITIONED NORTH OF THE AREA ALONG 32N/33N AND FOCUSED NEAR A 1013 MB LOW CENTERED NEAR 32N79W. THIS ACTIVITY IS FURTHER ENHANCED BY UPPER LEVEL DIFFLUENCE BETWEEN AN UPPER LEVEL RIDGE OVER THE WRN AND CENTRAL ATLC CENTERED NEAR 32N56W AND AN UPPER LEVEL TROUGH OVER THE SE CONUS AND FLORIDA PENINSULA. A 1026 MB SURFACE HIGH IS OVER THE CENTRAL ATLC NEAR 30N45W AND EXTENDS A RIDGE ACROSS THE REMAINDER OF THE SW NORTH ATLC...INCLUDING THE BAHAMAS... PROVIDING GENERALLY CLEAR SKIES AND FAIR WEATHER. HOWEVER...A WEAKNESS IN THE SURFACE RIDGE IS ANALYZED AS A SURFACE TROUGH THAT EXTENDS FROM 26N53W TO N OF PUERTO RICO NEAR 19N67W. SCATTERED SHOWERS ARE WITHIN 120 NM EITHER SIDE OF THE SURFACE TROUGH IN MODERATE ELY TRADES. $$ HUFFMAN