000 AXNT20 KNHC 241138 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT FRI JUL 24 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 1000 UTC. ...TROPICAL WAVES... A TROPICAL WAVE EXTENDS FROM 19N33W TO 9N29W MOVING W 10-15 KT. THIS WAVE COINCIDES WITH A DEEP LAYER MOISTURE MAXIMUM OBSERVED IN TOTAL PRECIPITABLE WATER IMAGERY. SATELLITE IMAGES INDICATE BROAD LOW-LEVEL CYCLONIC FLOW IN THE VICINITY OF THE WAVE AXIS. SATELLITE DERIVED WINDS ALSO INDICATE GOOD CYCLONIC TURNING IN THE LOW-MID LEVELS. CONVECTION IS LIMITED DUE TO THE THE PRESENCE OF A DRY SAHARAN AIR LAYER EXCEPT FOR A SMALL PORTION OF SCATTERED MODERATE CONVECTION EMBEDDED IN THE ITCZ FROM 8N-10N BETWEEN 29W-33W. A TROPICAL WAVE IS ALONG 71W S OF 20N MOVING W NEAR 25 KT. THIS WAVE COINCIDES WITH A DEEP LAYER MOISTURE MAXIMUM OBSERVED IN TOTAL PRECIPITABLE WATER IMAGERY. NO DEEP CONVECTION IS CURRENTLY ASSOCIATED WITH THIS WAVE DUE TO DRY AIR AND SUBSIDENCE IN NELY FLOW ALOFT. A TROPICAL WAVE IS ALONG 83W S OF 22N MOVING W NEAR 25 KT. CURRENT POSITION IS BASED MAINLY ON CONTINUITY DUE TO THE LACK OF GOOD PRESENCE IN SATELLITE IMAGERY. LITTLE DEEP CONVECTION IS CURRENTLY ASSOCIATED WITH THE WAVE DUE TO DRY SAHARAN AIR DIRECTLY TO THE E OF THE WAVE AXIS. HOWEVER...SCATTERED SHOWERS ARE WITHIN 100 NM EITHER SIDE OF THE WAVE AXIS FROM 17N-22N. A TROPICAL WAVE IS ALONG 97W S OF 21N MOVING W NEAR 25 KT. THIS WAVE IS EMBEDDED IN A BROAD AREA OF DEEP LAYER MOISTURE OBSERVED IN TOTAL PRECIPITABLE WATER IMAGERY. WHILE THE MAJORITY OF THE WAVE AXIS IS IN THE E PACIFIC...SCATTERED MODERATE/STRONG CONVECTION IS OVER MEXICO AND THE BAY OF CAMPECHE FROM 18N-20N BETWEEN 94W-96W. NUMEROUS MODERATE/SCATTERED STRONG CONVECTION IS FROM 14N-17N BETWEEN 93W-96W. THIS CONVECTION IS BEING ENHANCED BY UPPER LEVEL DIFFLUENCE. REFER TO THE TWDEP FOR MORE DETAILS ABOUT THE SRN PORTION OF THIS WAVE IN THE E PACIFIC. ...ITCZ... THE ITCZ AXIS IS CENTERED ALONG 11N13W 10N22W 9N37W 8N60W. SCATTERED MODERATE/STRONG CONVECTION IS FROM 7N-12N BETWEEN 20W-23W. SCATTERED MODERATE CONVECTION IS FROM 9N-11N BETWEEN 40W-45W. ...DISCUSSION... GULF OF MEXICO... LOW-LEVEL CONVERGENCE AHEAD OF A COLD FRONT ACROSS SRN ALABAMA...MISSISSIPPI...AND LOUISIANA ALONG WITH UPPER LEVEL DIFFLUENCE AND MOIST WLY FLOW ALOFT ARE SUPPORTING SCATTERED SHOWERS/THUNDERSTORMS OVER THE NRN GULF OF MEXICO N OF 27N BETWEEN 83W-92W. UPPER LEVEL DIFFLUENCE NEAR AN UPPER LEVEL HIGH OVER THE YUCATAN PENINSULA NEAR 18N95W AND LOW-LEVEL CONVERGENCE NEAR A TROPICAL WAVE ALONG 97W ARE SUPPORTING SCATTERED SHOWERS/ THUNDERSTORMS FROM 18N-20N BETWEEN 94W-96W. ELSEWHERE ACROSS THE GULF...A BROAD SURFACE RIDGE ANCHORED BY A 1016 MB HIGH NEAR 27N85W DOMINATES BRINGING GENERALLY FAIR WEATHER...AND IS SUPPORTED BY DRY AIR AND SUBSIDENCE ALOFT. WEAK ANTICYCLONIC FLOW IS PRESENT AROUND THE RIDGE WITH STRONGER WINDS IN THE SW GULF ESPECIALLY NEAR THE YUCATAN PENINSULA COAST. EXPECT THE SURFACE RIDGE TO GRADUALLY SHIFT SE AND EASTWARD THROUGH THE WEEKEND. E TO SE FLOW WILL INCREASE ACROSS THE W GULF BY LATE IN THE WEEKEND. CARIBBEAN SEA... UPPER LEVEL DIFFLUENCE BETWEEN THE UPPER LEVEL HIGH OVER THE YUCATAN PENINSULA NEAR 18N95W AND A SHORTWAVE UPPER LEVEL TROUGH OVER W CUBA IS SUPPORTING SCATTERED SHOWERS/THUNDERSTORMS ACROSS THE NW CARIBBEAN N OF 16N W OF 81W. THIS SHOWER ACTIVITY IS ENHANCED BY THE TROPICAL WAVE ALONG 83W. THE TROPICAL WAVE MAY ALSO BE ENHANCING A FEW ISOLATED SHOWERS IN THE SW CARIBBEAN S OF 14N BETWEEN 78W-82W. A FEW ISOLATED SHOWERS ARE OVER THE E CARIBBEAN S OF 15N BETWEEN 64W-67W ENHANCED BY UPPER LEVEL DIFFLUENCE. ELSEWHERE ACROSS THE CARIBBEAN...FAIR WEATHER PREVAILS UNDER THE PRESENCE OF A DRY SAHARAN AIR LAYER BETWEEN 70W-80W ALONG WITH SUBSIDENCE IN NELY FLOW ALOFT. FRESH TO STRONG TRADE WINDS ARE PRESENCE ACROSS THE MAJORITY OF THE CARIBBEAN. EXPECT THE TRADE WINDS TO INCREASE EARLY NEXT WEEK. ATLANTIC OCEAN... A MID-UPPER LEVEL TROUGH IS OVER THE W ATLC SUPPORTING A SURFACE TROUGH EXTENDING FROM 27N77W TO 32N71W CONTINUING N OF THE DISCUSSION AREA. LOW-LEVEL CONVERGENCE NEAR THE SURFACE TROUGH IS SUPPORTING SCATTERED SHOWERS OVER THE BAHAMAS FROM 23N-27N BETWEEN 75W-79W. UPPER LEVEL DIFFLUENCE BETWEEN THE UPPER LEVEL TROUGH OVER THE W ATLC AND AN UPPER LEVEL HIGH CENTERED N OF THE BAHAMAS NEAR 24N72W IS SUPPORTING AN AREA OF NUMEROUS SHOWERS/ THUNDERSTORMS FROM 24N-28N BETWEEN 69W-73W. UPPER LEVEL DIFFLUENCE ASSOCIATED WITH AN UPPER LEVEL LOW CENTERED NEAR 27N57W IS SUPPORTING SCATTERED SHOWERS/THUNDERSTORMS FROM 23N-25N BETWEEN 57W-62W. A SURFACE TROUGH IS ANALYZED IN THE CENTRAL ATLC EXTENDING FROM 27N41W TO 30N48W. NO SHOWER ACTIVITY IS CURRENTLY ASSOCIATED WITH THIS SURFACE TROUGH. THE REMAINDER OF THE ATLC IS DOMINATED BY A BROAD SURFACE RIDGE ANCHORED BY A 1026 MB HIGH N OF THE DISCUSSION AREA NEAR 37N35W BRINGING GENERALLY FAIR WEATHER ACROSS THE MAJORITY OF THE BASIN. AN UPPER LEVEL HIGH DOMINATES THE UPPER LEVELS IN THE CENTRAL AND E ATLC CENTERED NEAR 21N36W. IN THE TROPICAL ATLC...AN UPPER LEVEL LOW CENTERED NEAR 10N26N IS ENHANCING CONVECTION ALONG THE ITCZ BETWEEN 20W-24W. $$ WALTON