000 AXNT20 KNHC 101740 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT THU SEP 10 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. ...SPECIAL FEATURES... HURRICANE FRED IS CENTERED NEAR 16.8N 35.1W AT 10/1500 UTC OR ABOUT 640 NM W OF THE CAPE VERDE ISLANDS MOVING NW AT 6 KT. ESTIMATED CENTRAL PRESSURE IS 974 MB. MAXIMUM SUSTAINED WINDS HAVE DECREASED TO 85 KT WITH GUSTS TO 105 KT. FURTHER WEAKENING IS FORECAST DURING THE NEXT COUPLE DAYS. SCATTERED STRONG CONVECTION IS FROM 16N-18N BETWEEN 34W-36W. SCATTERED MODERATE CONVECTION IS FROM 18N-20N BETWEEN 31W-37W. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC FOR MORE DETAILS. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 73W S OF 18N MOVING W NEAR 15 KT. THE WAVE COINCIDES WITH A NARROW SURGE OF DEEP LAYER MOISTURE AND FOLLOWS A BROAD MAXIMUM OBSERVED IN TOTAL PRECIPITABLE WATER IMAGERY. THE NORTHERN PORTION OF THE WAVE LIES UNDER DRY SUBSIDENT AIR WHICH IS CURRENTLY INHIBITING DEEP CONVECTION NEAR THE WAVE AXIS. ...ITCZ... THE ITCZ AXIS IS CENTERED ALONG 12N17W 11N22W 15N28W 12N33W 10N50W 8N61W. ISOLATED MODERATE/STRONG CONVECTION IS FROM 6N-15N BETWEEN 13W-21W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 50 NM EITHER SIDE OF THE AXIS BETWEEN 35W-47W. ...DISCUSSION... GULF OF MEXICO... AS OF 1500 UTC...A SURFACE TROUGH LINES THE NW GULF OF MEXICO COASTLINE EXTENDING FROM THE LOUISIANA COAST NEAR 29N92W ALONG THE TEXAS COAST TO 28N96W CONTINUING S TO 24N97W. SURFACE CONVERGENCE NEAR THE TROUGH IS SUPPORTING SCATTERED SHOWERS/THUNDERSTORMS ACROSS THE W AND N CENTRAL GULF FROM 25N-30N W OF 87W...AND S OF 25N W OF 95W. A SECOND SURFACE TROUGH IS IN THE SE GULF EXTENDING FROM 26N83W THROUGH THE YUCATAN CHANNEL TO 19N86W. MOST OF THE ASSOCIATED SHOWERS ARE SE OF THE BASIN OVER CUBA. HOWEVER...KEY WEST FLORIDA RADAR AND RECENT LIGHTNING RADAR INDICATE ISOLATED SHOWERS/THUNDERSTORMS S OF 26N E OF 85W. IN THE UPPER LEVELS...NWLY TO NLY FLOW AROUND AN UPPER LEVEL RIDGE CENTERED W OF MEXICO NEAR 22N113W COVERS THE MAJORITY OF THE GULF. THE W SIDE OF AN UPPER LEVEL TROUGH DIPS ACROSS THE FLORIDA PENINSULA ASSOCIATED WITH AN UPPER LEVEL LOW OVER VIRGINIA. EXPECT SHOWERS/THUNDERSTORMS TO CONTINUE ACROSS THE BASIN AS THE TROUGH IN THE SE GULF DRIFTS NW AND A COLD FRONT WILL MOVE ACROSS TEXAS APPROACH THE NW GULF WATERS FRI. CARIBBEAN SEA... A SURFACE TROUGH EXTENDS FROM THE SE GULF OF MEXICO NEAR 26N83W INTO THE NW CARIBBEAN TO 19N86W. SURFACE CONVERGENCE NEAR THE TROUGH IS SUPPORTING SCATTERED SHOWERS/THUNDERSTORMS FROM 20N-23N BETWEEN 80W-85W INCLUDING WRN CUBA. THIS ACTIVITY IS ENHANCED BY UPPER LEVEL DIFFLUENCE BETWEEN THE UPPER LEVEL RIDGE OVER THE GULF AND AN UPPER LEVEL TROUGH EXTENDING FROM THE NW BAHAMAS ACROSS CENTRAL CUBA TO COSTA RICA. MOIST SWLY FLOW AROUND THE BASE OF THE UPPER TROUGH IS SUPPORTING SCATTERED SHOWERS/THUNDERSTORMS IN THE SW CARIBBEAN FROM 10N-14N BETWEEN 78W-82W. THE FLOW ALOFT TURNS WLY OVER THE ERN CARIBBEAN CONTINUING TO DRAW ENOUGH MOISTURE TO SUPPORT HIGH CIRRUS CLOUDS BETWEEN 13N-17N. DRY AIR ALOFT IS ON EITHER SIDE OF THIS BELT OF MOSITURE WHICH IS INHIBITING DEEP CONVECTION NEAR THE TROPICAL WAVE ALONG 73W. MODERATE TO FRESH TRADEWINDS ARE ACROSS MUCH OF THE BASIN BECOMING STRONG IN THE ERN CARIBBEAN. EXPECT THE TROUGH IN THE NW CARIBBEAN TO LIFT TO THE NW...AND THE TROPICAL WAVE ALONG 73W TO CONTINUE TO MOVE WWD. ATLANTIC OCEAN... A SURFACE TROUGH ENTERS THE DISCUSSION AREA NEAR 32N72W CONTINUING ALONG 29N76W TO THE S FLORIDA COAST NEAR 26N80W. SCATTERED SHOWERS/THUNDERSTORMS ARE WITHIN 300 NM SE OF THE TROUGH AXIS. SHOWERS HAVE PERSISTED OVER THIS AREA GENERATING LARGE AMOUNTS OF PRECIPITATION OVER SOME PORTIONS. AS OF 10/1200 UTC...FREEPORT BAHAMAS REPORTED 3.21 INCHES OF RAIN OVER THE PAST 24 HOURS. THE SHOWER ACTIVITY IS ENHANCED BY UPPER LEVEL DIFFLUENCE AROUND THE E SIDE OF AN UPPER LEVEL TROUGH EXTENDING FROM AN UPPER LEVEL LOW OVER VIRGINIA CONTINUING DOWN THE ERN UNITED STATES COASTLINE ACROSS CENTRAL CUBA TO THE SW CARIBBEAN. A 1015 MB SURFACE LOW IS N OF PUERTO RICO NEAR 21N65W. THE LOW IS SUPPORTED BY AN UPPER LEVEL LOW NEAR 26N65W. LOW-LEVEL CONVERGENCE NEAR THE SURFACE LOW IS SUPPORTING ISOLATED SHOWERS/POSSIBLE THUNDERSTORMS FROM 19N-27N BETWEEN 61W-68W. A WEAK 1020 MB SURFACE HIGH IS N OF THE SURFACE LOW CENTERED NEAR 29N60W. FARTHER E...A SURFACE TROUGH EXTENDS FROM 15N48W TO 24N46W. ISOLATED SHOWERS ARE ALONG THE TROUGH AXIS. A SECOND SURFACE TROUGH EXTENDS FROM 28N50W TO 31N45W. NO SHOWERS ARE CURRENTLY ASSOCIATED WITH THIS TROUGH. ELSEWHERE ACROSS THE ATLC...A SURFACE RIDGE BUILDS E OF 40W. IN THE UPPER LEVELS...AN UPPER LEVEL HIGH IS CENTERED NEAR 27N53W. AN UPPER LEVEL TROUGH EXTENDS TO THE E ALONG 32N34W TO 18N52W. ANOTHER UPPER LEVEL RIDGE DOMINATES THE TROPICAL AND ERN ATLC CENTERED E OF THE CAPE VERDE ISLANDS NEAR 17N20W SUPPORTING CONVECTION ALONG THE ITCZ AND HURRICANE FRED. $$ WALTON