000 AXNT20 KNHC 041738 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT TUE AUG 04 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 1700 UTC. ...TROPICAL WAVES... A TROPICAL WAVE IS ALONG 22W/23W S OF 16N MOVING W NEAR 10 KT. VISIBLE SATELLITE IMAGERY INDICATES LOW-LEVEL CYCLONIC FLOW IN THE VICINITY OF THE WAVE AXIS. THIS WAVE ALSO COINCIDES WITH A DEEP LAYER MOISTURE MAXIMUM OBSERVED IN TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 11N-15N BETWEEN 22W-25W. AN ACTIVE SURFACE TROUGH IS ALONG 34W/35W S OF 12N. WHILE IT IS CURRENTLY NOT ANALYZED AS A TROPICAL WAVE...IT MAY BE TRANSITIONED TO ONE ON FUTURE SURFACE ANALYSIS. MID-LEVEL CYCLONIC CIRCULATION IS NEAR THE TROUGH AXIS SUPPORTING SCATTERED MODERATE/ISOLATED STRONG CONVECTION FROM 7N-10N BETWEEN 33W-37W. HOWEVER...VISIBLE SATELLITE IMAGERY AND QUIKSCAT DATA AROUND 0800 UTC INDICATES THAT LOW LEVEL CYCLONIC CIRCULATION IS FARTHER E AROUND 30W. A TROPICAL WAVE EXTENDS ALONG 18N51W 14N48W 9N47W MOVING W NEAR 18 KT. VISIBLE SATELLITE IMAGERY AND SATELLITE DERIVED WINDS INDICATE LOW-LEVEL CYCLONIC FLOW IN THE VICINITY OF THE WAVE AXIS. THIS WAVE ALSO COINCIDES WITH A DEEP LAYER MOISTURE MAXIMUM OBSERVED IN TOTAL PRECIPITABLE WATER IMAGERY. THIS WAVE LEADS A DRY SAHARAN AIR LAYER WHICH IS INHIBITING DEEP CONVECTION NEAR THE WAVE. A TROPICAL WAVE IS ALONG 70W/71W S OF 18N MOVING W 15-20 KT. THIS WAVE HAS BEEN RELOCATED FROM ITS PREVIOUS POSITION ALONG 61W BASED ON CURRENT SATELLITE IMAGERY WHICH INDICATES LOW-LEVEL CYCLONIC FLOW OVER THE CENTRAL CARIBBEAN NEAR ITS CURRENT POSITION...AND TOTAL PRECIPITABLE WATER IMAGERY WHICH INDICATES A BROAD AREA OF INCREASED MOISTURE NEAR THE CURRENT WAVE POSITION. WHILE NO DEEP CONVECTION IS CURRENTLY ASSOCIATED WITH THE WAVE...SCATTERED SHOWERS ARE S OF HISPANIOLA FROM 17N-18N BETWEEN 69W-71W. ...THE ITCZ... THE ITCZ AXIS IS CENTERED ALONG 12N16W 11N28W 9N36W 12N50W 9N61W. SCATTERED MODERATE CONVECTION IS JUST OFF THE AFRICA COAST FROM 9N-13N BETWEEN 15W-18W. ...DISCUSSION... THE GULF OF MEXICO... A BROAD SURFACE RIDGE IS ACROSS THE GULF OF MEXICO ANCHORED BY A 1019 MB SURFACE HIGH NEAR 28N87W BRINGING GENERALLY FAIR WEATHER ACROSS THE AREA. HOWEVER...A SURFACE TROUGH IS ACROSS THE NRN FLORIDA PENINSULA FROM 29N84W TO 29N81W AND INTO THE ATLC. SURFACE CONVERGENCE NEAR THE TROUGH ALONG WITH UPPER LEVEL DIFFLUENCE BETWEEN AN UPPER LEVEL TROUGH OVER THE ERN CONUS AND AN UPPER LEVEL HIGH N OF THE BAHAMAS NEAR 27N79W ARE SUPPORTING ISOLATED SHOWERS/THUNDERSTORMS ACROSS THE NE GULF FROM 26N-30N E OF 90W. ANTICYCLONIC SURFACE FLOW IS PRESENT AROUND THE SURFACE RIDGE WITH WINDS REACHING 15 KT IN THE SW GULF. EXPECT THE SURFACE RIDGE TO PERSIST...AND A SURFACE TROUGH OVER ERN CUBA TO MOVE ACROSS THE STRAITS OF FLORIDA LATER TONIGHT. THE CARIBBEAN SEA... UPPER LEVEL DIFFLUENCE BETWEEN AN UPPER LEVEL TROUGH OVER THE YUCATAN PENINSULA AND AN UPPER LEVEL RIDGE OVER THE WRN CARIBBEAN CENTERED NEAR 10N83W OFF THE COAST OF COSTA RICA IS SUPPORTING ISOLATED SHOWERS/THUNDERSTORMS ACROSS THE NW CARIBBEAN N OF 16N W OF 78W. A SURFACE TROUGH...ORIGINALLY THE NRN PORTION OF THE TROPICAL WAVE ALONG 70W/71W...EXTENDS OVER ERN CUBA FROM 19N77W TO 21N78W AND INTO THE ATLC. SURFACE CONVERGENCE NEAR THE TROUGH IS SUPPORTING ISOLATED SHOWERS/THUNDERSTORMS N OF 18N BETWEEN 75W-78W. SCATTERED SHOWERS/THUNDERSTORMS ARE ACROSS THE SW CARIBBEAN S OF 12N BETWEEN 80W-84W ENHANCED BY SURFACE CONVERGENCE IN THE PROXIMITY OF THE E PACIFIC ITCZ. SCATTERED SHOWERS/THUNDERSTORMS ARE ALSO S OF HISPANIOLA FROM 17N-18N BETWEEN 69W-71W DUE TO THE TROPICAL WAVE ALONG 70W/71W. ACROSS THE REMAINDER OF THE CARIBBEAN...GENERALLY FAIR WEATHER IS PRESENT DUE TO DRY AIR ALOFT DESPITE UPPER LEVEL TROUGHING E OF 75W. EXPECT THE TROPICAL WAVE ALONG 70W/71W TO PROPAGATE WWD...AND THE NEXT TROPICAL WAVE TO REACH THE ERN CARIBBEAN TOMORROW. THE ATLANTIC OCEAN... A SURFACE TROUGH EXTENDS ACROSS THE NRN FLORIDA PENINSULA FROM 29N81W TO 32N77W CONTINUING OUT OF THE DISCUSSION AREA TO THE NE. SURFACE CONVERGENCE NEAR THE TROUGH ALONG WITH UPPER LEVEL DIFFLUENCE BETWEEN AN UPPER LEVEL TROUGH OVER THE ERN CONUS AND AN UPPER LEVEL HIGH N OF THE BAHAMAS NEAR 27N79W ARE SUPPORTING SCATTERED SHOWERS/THUNDERSTORMS N OF 28N W OF 71W. A SURFACE TROUGH EXTENDS ACROSS ERN CUBA TO THE BAHAMAS FROM 21N76W TO 25N75W SUPPORTING ISOLATED SHOWERS/POSSIBLE THUNDERSTORMS S OF 24N BETWEEN 75W-80W. THIS TROUGH ORIGINATED AS THE NRN PORTION OF THE TROPICAL WAVE ALONG 70W/71W. ANOTHER SURFACE TROUGH EXTENDS FROM 19N55W TO 22N57W. THIS TROUGH ALSO ORIGINATED AS THE NRN PORTION OF A TROPICAL WAVE EXTENDING ALONG 18N51W 14N48W 9N47W. ISOLATED SHOWERS ARE WITHIN 200 NM W OF THE TROUGH AXIS. ELSEWHERE ACROSS THE ATLC...A BROAD SURFACE RIDGE DOMINATES ANCHORED BY A 1028 MB SURFACE HIGH NEAR 36N49W BRINGING GENERALLY FAIR WEATHER ACROSS THE REMAINDER OF THE BASIN. IN THE UPPER LEVELS...AN UPPER LEVEL TROUGH IS BETWEEN 60W-70W CENTERED NEAR 28N63W. A BROAD UPPER LEVEL RIDGE DOMINATES THE ERN ATLC CENTERED NEAR 18N49W. $$ WALTON