000 AXNT20 KNHC 121029 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT SUN JUL 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1015 UTC. ...TROPICAL WAVES... A TROPICAL WAVE IS ALONG 42W/43W S OF 20N MOVING W 15-20 KT. SATELLITE IMAGERY INDICATES THAT THE WAVE COINCIDES WITH A BROAD AREA OF CYCLONIC TURNING IN THE LOW-LEVELS. DEEP CONVECTION REMAINS ABSENT IN THE VICINITY OF THE WAVE SUPPRESSED BY SAHARAN DUST. A TROPICAL WAVE EXTENDS FROM 20N78W TO 9N80W MOVING W 20-25 KT. THE WAVE POSITION IS MAINLY BASED ON A MOISTURE MAXIMUM IN TOTAL PRECIPITABLE WATER AS LITTLE SIGNATURE IS APPARENT IN SATELLITE IMAGERY OR OBSERVATIONS. CONVECTION IS LOCATED WELL W OF THE WAVE FROM 11N-17N BETWEEN 80W-85W ENHANCED BY DIFFLUENCE ALOFT. ...ITCZ... THE ITCZ AXIS IS CENTERED ALONG 11N15W 8N23W 8N38W 7N48W 7N59W. SCATTERED MODERATE CONVECTION IS FROM 6N-12N BETWEEN 15W-25W. SCATTERED MODERATE CONVECTION IS ALSO FROM 3N-6N BETWEEN 42W-49W. ...DISCUSSION... GULF OF MEXICO... EAST-NORTHEASTERLY UPPER FLOW COVERS MUCH OF THE GULF ON THE SE SIDE OF AN UPPER RIDGE OVER THE SOUTHERN PLAINS OF THE CONUS...WITH SUBSIDENCE SUPPORTING A SURFACE RIDGE ALONG 30N. AS A RESULT...GENERALLY FAIR WEATHER CONDITIONS ARE PRESENT ACROSS THE N HALF OF THE GULF. ACROSS THE SW GULF...AN UPPER LEVEL LOW IS CENTERED NEAR 19N93W WITH AN ASSOCIATED SURFACE TROUGH ALONG 95W S OF 22N. ATMOSPHERIC INSTABILITY NEAR THE UPPER LOW AND LOW LEVEL CONVERGENCE NEAR THE SURFACE TROUGH ARE SUPPORTING SCATTERED SHOWERS AND THUNDERSTORMS ACROSS THE SW GULF S OF 22N W OF 95W. WINDS ARE LIGHT AND VARIABLE IN THE VICINITY OF THE SURFACE RIDGE ACROSS THE N GULF...WITH ANTICYCLONIC FLOW AROUND THE RIDGE SUPPORTING A BROAD SWATH OF E WINDS OF 10 TO 15 KT ACROSS THE SOUTHERN HALF OF THE GULF...HIGHEST NEAR THE STRAITS OF FLORIDA. HOWEVER...ELY WINDS ARE IN THE 20-25 KT RANGE IN THE VICINITY OF THE AFOREMENTIONED SURFACE TROUGH. CARIBBEAN SEA... FRESH TO STRONG TRADE WINDS ARE OCCURRING BETWEEN THE SUBTROPICAL RIDGE OVER THE CENTRAL ATLC AND A BROAD TROUGH OVER NORTHERN SOUTH AMERICA...WITH THE STRONGEST FLOW NEAR THE COAST OF COLOMBIA. AN EARLIER QUIKSCAT PASS CONFIRMED THAT E WINDS OF 25 TO 30 KT ARE PRESENT NEAR THE COAST OF COLOMBIA. THESE WINDS WILL REMAIN STRONG OVER THE NEXT SEVERAL DAYS AS THE SUBTROPICAL RIDGE STRENGTHENS. ALOFT...AN UPPER LEVEL TROUGH IS OVER THE N CENTRAL CARIBBEAN. ATMOSPHERIC INSTABILITY ASSOCIATED WITH THIS FEATURE IS RESULTING IN ISOLATED SHOWERS AND THUNDERSTORMS N OF 19N BETWEEN 76W-80W INCLUDING PORTIONS OF E CUBA. ACROSS THE SW CARIBBEAN...AN UPPER LEVEL HIGH IS CENTERED NEAR 12N78W...WITH ASSOCIATED UPPER LEVEL DIVERGENCE SUPPORTING SCATTERED SHOWERS AND THUNDERSTORMS FROM 10N-16N W OF 80W INCLUDING ADJACENT AREAS OF CENTRAL AMERICA. ACROSS THE E CARIBBEAN...DEEP LAYER DRY AIR AND ATMOSPHERIC STABILITY ASSOCIATED WITH AN UPPER LEVEL RIDGE ARE SUPPORTING GENERALLY FAIR WEATHER. ATLANTIC OCEAN... AN UPPER LEVEL TROUGH IS ACROSS THE SW NORTH ATLC WITH AN AXIS EXTENDING FROM 26N75W TO 32N76W TO NE OF THE DISCUSSION AREA. AMOSPHERIC INSTABILITY ASSOCIATED WITH THE UPPER TROUGH IS SUPPORTING SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS FROM 21N-26N W OF 63W INCLUDING THE BAHAMAS. FARTHER E...A SURFACE TROUGH EXTENDS FROM 24N56W TO 16N58W...WITH DEEP LAYER MOISTURE AND LOW LEVEL CONVERGENCE SUPPORTING SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS WITHIN 60 NM EITHER SIDE OF THE SURFACE TROUGH. SUBSIDENCE AND GENERALLY FAIR WEATHER ARE PRESENT ACROSS MUCH OF THE CENTRAL AND E ATLC AROUND A BROAD SURFACE RIDGE. THIS RIDGE IS ASSOCIATED WITH A 1026 MB SURFACE HIGH NEAR 33N49W. HOWEVER...A SURFACE TROUGH EXTENDS FROM THE W COAST OF AFRICA NEAR 18N16W TO 16N21W...WITH WELL-DEFINED CYCLONIC CURVATURE IN THE LOW LEVEL FLOW REVEALED BY THE 11/2300 UTC ASCAT PASS. LOW LEVEL CONVERGENCE IS SUPPORTING SCATTERED SHOWERS WITHIN 60 NM EITHER SIDE OF THE SURFACE TROUGH. $$ COHEN/CANGIALOSI