000 AXNT20 KNHC 190042 AAA TWDAT TROPICAL WEATHER DISCUSSION...UPDATED NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT TUE AUG 18 2009 UPDATED FOR HURRICANE BILL...NOW MAJOR HURRICANE 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2330 UTC. ...SPECIAL FEATURES... AS OF 2130 UTC...REPORTS FROM A NOAA HURRICANE HUNTER PLANE INDICATE THAT HURRICANE BILL HAS BECOME A STRONG CATEGORY 3 HURRICANE WITH MAXIMUM SUSTAINED WIND SPEEDS OF 110 KT. AT 2100 UTC...THE CENTER OF HURRICANE BILL WAS LOCATED BY AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT NEAR 16.6N 52.2W OR ABOUT 635 MILES...1025 KM...EAST OF THE LEEWARD ISLANDS. BILL IS MOVING TOWARD THE WEST-NORTHWEST OR 290 DEGREES AT 14 KT. THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 962 MB. HURRICANE FORCE WINDS EXTEND OUTWARD UP TO 45 MILES...75 KM...FROM THE CENTER...AND TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 175 MILES...280 KM. WEST-NORTHWEST MOTION IS EXPECTED TO CONTINUE TONIGHT...FOLLOWED BY A TURN TOWARD THE NORTHWEST ON WEDNESDAY. PLEASE READ THE LATEST FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS TCMAT3/WTNT23 KNHC FOR MORE DETAILS. NUMEROUS STRONG CONVECTION SURROUNDS THE CENTER OF BILL AND IS FROM 13N-18N BETWEEN 50W-55W. ...TROPICAL WAVES... A TROPICAL WAVE EXTENDS FROM 16N38W TO 8N34W MOVING W NEAR 15 KT. THE WAVE IS AHEAD OF A DEEP LAYER MOISTURE MAXIMUM OBSERVED IN TOTAL PRECIPITABLE WATER IMAGERY. THE MOISTURE IS BEING DRAWN INTO THE CIRCULATION OF HURRICANE BILL WHICH EXPLAINS THE TILTED AXIS OF THE WAVE. THE WAVE ALSO LEADS A DRY SAHARAN AIR LAYER WHICH IS INHIBITING ANY DEEP CONVECTION NEAR THE WAVE. HOWEVER...ISOLATED SHOWERS ARE FROM 6N-9N BETWEEN 33W-37W AND FROM 14N-16N BETWEEN 34W-37W. A TROPICAL WAVE IS ALONG 77W S OF 21N MOVING W NEAR 25 KT. THIS WAVE ORIGINATED AS THE REMNANTS OF ANA THAT DISSIPATED YESTERDAY. WHILE THERE IS A LOW PROBABILITY OF REGENERATION...SHOWERS/THUNDERSTORMS ARE AFFECTING A LARGE AREA INCLUDING CUBA...THE BAHAMAS AND S FLORIDA. NUMEROUS MODERATE/SCATTERED STRONG CONVECTION IS FROM 18N-27N BETWEEN 75W-80W. THIS ACTIVITY IS ENHANCED BY UPPER LEVEL DIFFLUENCE. ...THE ITCZ... THE ITCZ AXIS IS CENTERED ALONG 12N16W 10N25W 11N33W 9N39W 12N46W 10N62W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 11N-15N BETWEEN 17W-22W. SCATTERED MODERATE CONVECTION IS FROM 7N-10N BETWEEN 21W-26W. ...DISCUSSION... THE GULF OF MEXICO... THE GULF OF MEXICO IS WET TONIGHT AS SHOWERS/THUNDERSTORMS ARE ACROSS MUCH OF THE BASIN. SCATTERED SHOWERS/THUNDERSTORMS N OF 29N BETWEEN 85W-97W ALONG THE COASTLINE OF THE GULF STATES ARE ENHANCED BY SURFACE CONVERGENCE NEAR A TROUGH N OF THE DISCUSSION AREA ACROSS LOUISIANA AS WELL AS UPPER LEVEL DIFFLUENCE BETWEEN AN UPPER LEVEL RIDGE ACROSS THE GULF OF MEXICO CENTERED NEAR 27N90W AND AN UPPER LEVEL TROUGH ACROSS THE CENTRAL UNITED STATES. UPPER LEVEL DIFFLUENCE BETWEEN THE UPPER HIGH AND AN UPPER LEVEL LOW OVER CENTRAL MEXICO NEAR 23N102W IS SUPPORTING SCATTERED SHOWERS/THUNDERSTORMS ALONG THE E COAST OF MEXICO FROM 21N-24N BETWEEN 95W-98W. UPPER LEVEL DIFFLUENCE BETWEEN THE UPPER HIGH AND ANOTHER UPPER LEVEL LOW S OF CUBA NEAR 20N80W IS SUPPORTING SCATTERED SHOWERS/THUNDERSTORMS ACROSS THE YUCATAN PENINSULA AND THE ADJACENT COASTAL WATERS IN THE BAY OF CAMPECHE. SCATTERED SHOWERS/THUNDERSTORMS ARE ACROSS THE W COAST OF FLORIDA FROM 25N-30N BETWEEN 81W-84W ENHANCED BY UPPER LEVEL DIFFLUENCE BETWEEN THE UPPER HIGH AND AN UPPER LEVEL TROUGH OVER THE NW ATLC. FINALLY...ISOLATED SHOWERS/THUNDERSTORMS ARE ACROSS THE CENTRAL GULF FROM 23N-28N BETWEEN 86W-91W. EXPECT SHOWERS/THUNDERSTORMS TO CONTINUE ACROSS THE GULF AS THE TROPICAL WAVE ALONG 77W...REMNANTS OF ANA...MOVE WWD. THE CARIBBEAN SEA... ISOLATED SHOWERS/THUNDERSTORMS ARE ACROSS THE FAR NW CARIBBEAN N OF 17N BETWEEN 81W-86W. THIS ACTIVITY IS ENHANCED BY UPPER LEVEL DIFFLUENCE BETWEEN AN UPPER LEVEL LOW S OF CUBA NEAR 20N80W AND AN UPPER LEVEL RIDGE THAT DOMINATES THE GULF OF MEXICO. UPPER LEVEL DIFFLUENCE BETWEEN THE UPPER LOW AND AN UPPER LEVEL HIGH E OF THE BAHAMAS NEAR 25N70W IS ENHANCING NUMEROUS SHOWERS/THUNDERSTORMS ACROSS E CUBA N OF 18N BETWEEN 75W-80W. THIS ACTIVITY IS ALSO ENHANCED BY SURFACE CONVERGENCE NEAR THE TROPICAL WAVE ALONG 77W...PREVIOUSLY THE REMNANTS OF ANA. ISOLATED SHOWERS/THUNDERSTORMS ARE IN THE SW CARIBBEAN S OF 12N BETWEEN 73W-81W ENHANCED BY THE S PORTION OF THE TROPICAL WAVE AS WELL AS THE E PACIFIC ITCZ. ELSEWHERE ACROSS THE CARIBBEAN...DRY AIR ASSOCIATED WITH A SAHARAN AIR LAYER E OF 68W AND SUBSIDENCE ALOFT ARE SUPPORTING GENERALLY FAIR WEATHER. EXPECT SHOWERS/THUNDERSTORMS TO CONTINUE ACROSS THE NW CARIBBEAN AS THE TROPICAL WAVE...REMNANTS OF ANA...MOVE WWD. THE ATLANTIC OCEAN... NUMEROUS SHOWERS/THUNDERSTORMS ARE ACROSS THE SW N ATLC FROM 21N-28N BETWEEN 75W-81W...INCLUDING THE BAHAMAS AND S FLORIDA. THIS ACTIVITY IS ENHANCED BY SURFACE CONVERGENCE NEAR THE TROPICAL WAVE ALONG 77W...AND A SURFACE TROUGH EXTENDING FROM 24N80W TO 27N76W ACROSS THE NW BAHAMAS. THIS ACTIVITY IS ALSO ENHANCED BY UPPER LEVEL DIFFLUENCE BETWEEN AN UPPER LEVEL LOW S OF CUBA NEAR 20N80W AND AN UPPER LEVEL HIGH E OF THE BAHAMAS NEAR 25N70W. UPPER LEVEL DIFFLUENCE BETWEEN THIS UPPER HIGH AND AN UPPER LEVEL TROUGH N OF 30N WITH AXIS ALONG 75W IS ENHANCING SCATTERED SHOWERS/THUNDERSTORMS FROM 27N-30N BETWEEN 67W-70W. A COLD FRONT DIPS INTO THE CENTRAL ATLC NEAR 32N44W EXTENDING TO 28N54W. NO SHOWER ACTIVITY IS CURRENTLY ASSOCIATED WITH THE FRONT. ELSEWHERE ACROSS THE ATLC...A BROAD SURFACE RIDGE DOMINATES ANCHORED BY A 1023 MB HIGH NEAR 34N74W...A 1022 MB HIGH NEAR 33N61W...AND ANOTHER 1022 MB HIGH NEAR 32N31W. IN THE UPPER LEVELS...AN UPPER LEVEL TROUGH IS BETWEEN 36W-62W N OF 29N...AND AN UPPER LEVEL HIGH IS CENTERED NEAR 30N30W DOMINATING THE E ATLC. ACROSS THE TROPICAL ATLC...A BROAD UPPER LEVEL HIGH IS CENTERED NEAR 20N30W ENHANCING CONVECTION ALONG THE ITCZ NEAR THE AFRICA COAST. $$ WALTON