000 AXNT20 KNHC 190554 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT WED AUG 19 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0415 UTC. ...SPECIAL FEATURES... HURRICANE BILL IS CENTERED NEAR NEAR 17.2N 53.4W OR ABOUT 480 NM EAST OF THE LEEWARD ISLANDS MOVING WNW AT 13 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 952 MB. MAXIMUM SUSTAINED WIND SPEED IS 110 KT WITH GUSTS TO 135 KT. SEE THE LATEST FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS TCMAT3/WTNT23 KNHC FOR MORE DETAILS. SCATTERED/NUMEROUS STRONG CONVECTION IS WITHIN 120 NM OF THE CENTER IN THE SW QUADRANT WITH SCATTERED MODERATE/STRONG CONVECTION COVERING THE REMAINDER OF THE AREA FROM 14N-20N BETWEEN 50W-56W. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM 16N39W TO 8N34W MOVING W 15-20 KT. WAVE IS AT THE LEADING EDGE OF AN AREA DEEP LAYER MOISTURE MAXIMUM OBSERVED IN TOTAL PRECIPITABLE WATER IMAGERY WHICH CONTINUES TO BE DRAWN INTO THE CIRCULATION OF HURRICANE BILL CAUSING THE TILTED AXIS. ISOLATED SHOWERS ARE WITHIN 60/75 NM OF LINE FROM 15N43W TO 12N28W. TROPICAL WAVE IS ALONG 79W/80W S OF 22N MOVING W NEAR 25 KT. THIS WAVE RESULTED FROM THE REMNANTS OF ANA AND IS NOT DISPLAYING THE TYPICAL CHARACTERISTICS OF A TROPICAL WAVE...SUCH AS BEING EMBEDDED WITHIN DEEP LAYERED MOISTURE. IT IS IN AN AREA OF DRY STABLE AIR AND NOT PRODUCING ANY SHOWERS/CONVECTION. ...THE ITCZ... THE ITCZ AXIS IS CENTERED ALONG 13N16W 11N25W 12N34W THEN ALONG 10N38W 13N47W THEN ALONG 11N56W 9N62W. SCATTERED MODERATE/ ISOLATED STRONG CONVECTION IS FROM 5N-8N BETWEEN 42W-45W. CLUSTERS OF SIMILAR CONVECTION ARE 7N-13N BETWEEN 19W-26W. ...DISCUSSION... GULF OF MEXICO... BROAD UPPER RIDGE COVERS THE W AND CENTRAL GULF WHILE A UPPER LOW IN THE CARIBBEAN EXTENDS AN UPPER TROUGH OVER THE E GULF PROVIDING ABUNDANCE OF UPPER LEVEL MOISTURE ACROSS THE ENTIRE AREA. A WEAK SURFACE TROUGH EXTENDS FROM THE W YUCATAN PENINSULA NEAR 19N90W TO OVER THE CENTRAL GULF TO 28N88W. SCATTERED SHOWERS/THUNDERSTORMS ARE S OF 20N ACROSS THE ENTIRE BAY OF CAMPECHE TO INLAND OVER MEXICO. ISOLATED SHOWERS DOT THE REMAINDER OF THE GULF. CARIBBEAN SEA... THE MOST SIGNIFICANT FEATURE FOR THE CARIBBEAN TONIGHT IS THE UPPER LOW CENTERED NEAR 20N83W COVERING THE NW CARIBBEAN AND EXTENDING AN UPPER TROUGH N OVER THE E GULF OF MEXICO AND SE TO NEAR 12N76W. THIS FEATURE IS GENERATING SCATTERED SHOWERS/ THUNDERSTORMS N OF 18N OVER CUBA AND THE YUCATAN CHANNEL BETWEEN 83W-87W AND ISOLATED SHOWERS/THUNDERSTORMS OVER THE SW CARIBBEAN WITHIN 60 NM OF 11N FROM 75W-82W. FRESH TO STRONG EASTERLY TRADE WINDS CONTINUE ACROSS THE AREA. DRY STABLE AIR ACROSS THE AREA E OF 80W IS LIMITING ANY SHOWERS RESULTING IN FAIR CONDITIONS TONIGHT ACROSS THE REMAINDER OF THE CARIBBEAN. HOWEVER... SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS WILL BE APPROACHING THE LEEWARD ISLANDS DURING THE NIGHT AS HURRICANE BILL MOVES NW OF THE ISLANDS. ATLANTIC OCEAN... THE MAIN FOCUS TONIGHT FOR THE ATLC IS MAJOR HURRICANE BILL. THE UPPER TROUGH OVER THE E GULF OF MEXICO AND NW CARIBBEAN COVERS THE SW ATLC...AN UPPER RIDGE IS JUST TO THE E EXTENDING FROM HISPANIOLA TO JUST W OF BERMUDA...AND TO THE E OF BERMUDA IS AN UPPER LOW NEAR 32N61W. THIS SCENARIO IS PROVIDING DIFFLUENCE ALOFT TO GENERATE SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM 23N-29N BETWEEN 76W TO JUST INLAND OVER THE FLORIDA PENINSULA NEAR 81W WITH ISOLATED SHOWERS/THUNDERSTORMS DOTTING THE AREA WITHIN 120 NM OF LINE FROM 28N76W TO 32N63W. OTHERWISE THE ATLC BASIN IS DOMINATED BY A SURFACE RIDGE ANCHORED BY A 1022 MB HIGH OVER THE W ATLC JUST N OF THE REGION NEAR 33N73W AND BY A 1023 MB HIGH NEAR 30N32W IN THE E WITH A WEAKNESS OVER THE CENTRAL ATLC COMPLIMENTS OF HURRICANE BILL. $$ WALLACE