000 AXNT20 KNHC 081757 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT WED JUL 08 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 45W MOVING W NEAR 15 KT. A WEAK LOW- LEVEL INVERTED-V CLOUD SIGNATURE IS OBSERVED ON VISIBLE SATELLITE IMAGERY ALONG WITH A LARGE AREA OF SAHARAN DUST SURROUNDING THE WAVE THAT COVERS THE TROPICAL ATLC E OF 55W TO W AFRICA. WITH THE DRY SAHARAN AIR LAYER SURROUNDING THE WAVE...NO DEEP CONVECTION IS IN THE VICINITY OF THE WAVE. A TROPICAL WAVE EXTENDS FROM THE NRN YUCATAN PENINSULA NEAR 21N87W ALONG 14N89W AND INTO THE E PACIFIC MOVING W NEAR 18 KT. THIS WAVE COINCIDES WITH A SIGNIFICANT AREA OF INCREASED PRECIPITABLE WATER ACROSS THE WRN CARIBBEAN AND CENTRAL AMERICA. INTERACTING WITH A DIFFLUENT ATMOSPHERE ALOFT...SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FOUND ACROSS THE WRN CARIBBEAN AND PORTIONS CENTRAL AMERICA FROM 14N-19N BETWEEN 82W-90W. ...ITCZ... THE ITCZ AXIS IS CENTERED ALONG 12N16W 7N25W 6N43W 7N48W 9N61W. SCATTERED MODERATE CONVECTION IS FROM 4N-10N BETWEEN 11W-27W. ...DISCUSSION... GULF OF MEXICO... MOSTLY S TO SW SURFACE WINDS ARE OBSERVED ACROSS THE GULF OF MEXICO AS A RIDGE OF HIGH PRESSURE EXTENDS FROM THE W ATLC THROUGH THE STRAITS OF FLORIDA AND WRN CUBA TO THE ERN COAST OF MEXICO. A 1130 UTC SCATTEROMETER PASS DEPICTED WINDS UP TO 15 KT ACROSS THE ERN AND NW GULF...ALONG WITH S-SE WINDS UP TO 20 KT ACROSS THE SW GULF AND BAY OF CAMPECHE. AS THE WIND FIELD ROUNDS THE RIDGE AXIS POSITIONED ACROSS THE CENTRAL GULF...LOW-LEVEL CONVERGENCE ALONG A SURFACE TROUGH EXTENDING FROM THE WRN FLORIDA PANHANDLE TO 30N95W S OF NEW ORLEANS IS GENERATING SCATTERED SHOWERS AND TSTMS N OF 26N E OF 93W OVER THE NRN GULF COAST AND NRN FLORIDA. AN UPPER LEVEL SHORTWAVE TROUGH IS PROGRESSING E-SE ACROSS THE SE CONUS AND IS ALSO ENHANCING THIS ACTIVITY. ELSEWHERE ACROSS THE REMAINDER OF THE GULF S OF 27N...MOSTLY CLEAR SKIES ARE NOTED ON VISIBLE SATELLITE IMAGERY AS SURFACE RIDGING AND MODERATE SUBSIDENCE ALOFT PREVAIL. CARIBBEAN SEA... A TROPICAL WAVE IS TRACKING WWD ACROSS THE ERN YUCATAN PENINSULA AND CENTRAL AMERICA CONTINUING TO IMPACT THE NW CARIBBEAN WATERS AND PORTIONS OF CENTRAL AMERICA. THE WAVE CONTINUES TO MOVE BENEATH AN UPPER LEVEL ANTICYCLONE CENTERED OVER WRN GUATEMALA NEAR 15N92W AND THE INTERACTION BETWEEN THESE TWO FEATURES IS GENERATING SCATTERED SHOWERS AND TSTMS FROM 14N-19N BETWEEN 82W-90W...INCLUDING PORTIONS OF HONDURAS...BELIZE AND GUATEMALA. ALSO SCATTERED SHOWERS AND TSTMS ARE ACROSS THE SW CARIBBEAN AND FAR ERN COASTAL AREAS OF WRN PANAMA...COSTA RICA AND SE NICARAGUA FROM 8N-13N W OF 80W. SURFACE CONVERGENCE DUE TO THE PROXIMITY OF THE E PACIFIC ITCZ ALONG 8N IS ENHANCING THIS ACTIVITY. THE REMAINDER OF THE CARIBBEAN...WITH THE EXCEPTION OF THE FAR NERN WATERS...IS UNDER THE INFLUENCE OF A SAHARAN AIR LAYER OF DUST SUSPENDED IN THE MIDDLE LEVELS OF THE ATMOSPHERE. THE SUSPENDED DUST IS OBSERVED ON VISIBLE SATELLITE IMAGERY AND NUMEROUS OF THE UPPER AIR TIME SECTION ANALYSES ACROSS THE ERN AND CENTRAL CARIBBEAN. WITH THIS DRIER AIR IN PLACE...ONLY A FEW ISOLATED LOW-LEVEL SHOWERS ARE NOTED N OF 16N E OF 67W IN ASSOCIATION WITH A SURFACE TROUGH THAT EXTENDS FROM THE CENTRAL ATLC TO NEAR MONTSERRAT. FRESH TO STRONG ELY TRADE WIND FLOW CONTINUES ACROSS THE BASIN AND IS FORECAST TO PERSIST THROUGH FRIDAY AND INTO THE WEEKEND. ATLANTIC OCEAN... SCATTERED SHOWERS AND TSTMS ARE ACROSS THE SW NORTH ATLC N OF 29N W OF 68W. THIS ACTIVITY IS DRIVEN BY LOW-LEVEL CONVERGENCE ALONG AND S OF A STATIONARY FRONT THAT PARALLELS 32N BETWEEN 73W AND THE SOUTH CAROLINA COAST. THIS ACTIVITY IS FURTHER ENHANCED BY UPPER LEVEL DIFFLUENCE BETWEEN AN UPPER LEVEL RIDGE OVER THE W ATLC CENTERED NEAR 29N67W AND AN UPPER LEVEL SHORTWAVE TROUGH OVER THE SE CONUS. A 1023 MB SURFACE HIGH IS OVER THE CENTRAL ATLC NEAR 29N42W AND EXTENDS A RIDGE ACROSS THE REMAINDER OF THE SW NORTH ATLC...INCLUDING THE BAHAMAS...PROVIDING GENERALLY FAIR WEATHER. HOWEVER...A WEAKNESS IN THE SURFACE RIDGE IS ANALYZED AS A SURFACE TROUGH THAT EXTENDS FROM 25N47W TO THE LEEWARD ISLANDS NEAR 16N62W. SCATTERED SHOWERS ARE WITHIN 150 NM W OF THE SURFACE TROUGH IN MODERATE ELY TRADES. ANOTHER WEAKNESS IN THE SURFACE RIDGE LOCATED ACROSS THE NE ATLC IS A SURFACE TROUGH THAT ENTERS THE DISCUSSION AREA NEAR 32N22W AND EXTENDS S-SW TO 24N28W. POSSIBLE ISOLATED SHOWERS ARE WITHIN 60 NM EITHER SIDE OF THE TROUGH. $$ HUFFMAN