000 AXNT20 KNHC 222347 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SAT AUG 22 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...SPECIAL FEATURES... HURRICANE BILL IS CENTERED NEAR 37.8N 68.3W AT 23/0000 UTC OR ABOUT 220 NM SSE OF NANTUCKET MASSACHUSETTS AND ABOUT 480 NM SSW OF HALIFAX NOVA SCOTIA MOVING TO THE NORTH AT 21 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 961 MB. MAXIMUM SUSTAINED WIND SPEED IS 75 KT WITH GUSTS TO 90 KT. SCATTERED MODERATE CONVECTION IS LOCATED WITHIN 300 NM OF THE CENTER IN THE NE QUADRANT. SCATTERED SHOWERS ARE ELSEWHERE WITHIN 300 NM OF THE CENTER IN THE NW QUADRANT. SEE LATEST NHC INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT3/ WTNT23 KNHC AND THE FULL FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT3/WTNT23 KNHC FOR MORE DETAILS. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 17W S OF 17N MOVING W AT 10 KT. LOW-LEVEL CYCLONIC CURVATURE IS NOTED IN THE CLOUD FIELD ALONG THE WAVE AXIS N OF 11N. SCATTERED SHOWERS ARE FROM 9N-20N E OF 20W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS NOTED ACROSS INTERIOR W AFRICA FROM 10N-13N BETWEEN 9W-17W. TROPICAL WAVE IS ALONG 42W S OF 18N MOVING W AT 20-25 KT. A 1009 MB LOW IS ALONG THE WAVE AXIS NEAR 12N. THIS WAVE COINCIDES WITH A MAXIMUM IN TOTAL PRECIPITABLE WATER AND REMAINS EMBEDDED WITHIN AN ELONGATED ARE OF CYCLONIC CURVATURE S OF 16N BETWEEN 35W-48W. ISOLATED MODERATE CONVECTION IS FROM 12N-16N BETWEEN 40W-46W. TROPICAL WAVE IS ALONG 64W S OF 17N MOVING W AT 15-20 KT. AN AREA OF MAXIMUM TOTAL PRECIPITABLE WATER IS MOVING ACROSS THE SE CARIBBEAN WITH SCATTERED MODERATE/ISOLATED STRONG CONVECTION FROM 7N-13N BETWEEN 60W-68W. ...ITCZ... THE ITCZ IS CENTERED ALONG 11N19W 13N31W 12N40W 11N43W 8N52W 9N62W. ASIDE FROM CONVECTION ASSOCIATED WITH THE TROPICAL WAVES...WIDELY SCATTERED MODERATE CONVECTION IS FROM 8N-12N BETWEEN 21W-27W. ...DISCUSSION... GULF OF MEXICO... AN UPPER LEVEL TROUGH IS OVER THE SE CONUS AND DIPS SWD INTO THE EXTREME NRN GULF N OF 27N. THIS UPPER LEVEL FEATURE SUPPORTS A COLD FRONT THAT EXTENDS FROM THE FAR WRN FLORIDA PANHANDLE TO NEW ORLEANS LOUISIANA AND WWD TO GALVESTON TEXAS. A PRE-FRONTAL TROUGH IS ALSO ANALYZED SE OF THE COLD FRONT FROM NE FLORIDA INTO THE GULF NEAR 29N83W SW TO 26N88W. SATELLITE IMAGERY AND LIGHTNING DATA INDICATE SCATTERED SHOWERS AND TSTMS DEVELOPING ACROSS MUCH OF THE NRN GULF WATERS FROM 25N-29N BETWEEN 83W-94W. SIMILAR CONVECTION IS ALSO OCCURRING ACROSS THE SE FLORIDA PENINSULA E OF 81W. AN EXTENSION OF THIS UPPER LEVEL TROUGH IS FOUND ALONG 90W TO AN UPPER LEVEL LOW CENTERED NEAR 20N90W. ATMOSPHERIC LIFT AND INSTABILITY ASSOCIATED WITH THIS UPPER LEVEL LOW IS GENERATING SCATTERED SHOWERS AND ISOLATED TSTMS ACROSS THE YUCATAN PENINSULA FROM 19N-22N. ELSEWHERE ACROSS THE WRN GULF A 1018 MB SURFACE HIGH IS CENTERED NEAR 26N93W. WHILE CONVECTIVE ACTIVITY ENCOMPASSES MUCH OF THE CENTRAL GULF...W OF 94W AND S OF 24N ARE AREAS OF FAIR WEATHER AND RELATIVELY LITTLE CLOUD COVER THIS EVENING. CARIBBEAN SEA... A TROPICAL WAVE IS OVER THE SE CARIBBEAN ALONG 64W BRINGING SCATTERED SHOWERS AND ISOLATED TSTMS S OF 13N E OF 68W. THIS WAVE AND ASSOCIATED ISOLATED TRADE WIND SHOWERS ARE MOVING WWD ON THE SRN PERIPHERY OF AN UPPER LEVEL ANTICYCLONIC CIRCULATION CENTERED N OF PUERTO RICO NEAR 20N67W THAT ENCOMPASSES MOST OF THE CARIBBEAN BASIN TO 85W. MOSTLY MODERATE SUBSIDENCE WITH A FEW AREAS OF STRONGER SUBSIDENCE ARE NOTED ON WATER VAPOR IMAGERY ACROSS THE BASIN THAT ARE INHIBITING ANY AREAS OF ORGANIZED DEEP CONVECTION. HOWEVER...WITH THE PROXIMITY OF THE ITCZ AXIS ALONG 8N ACROSS SRN PORTIONS OF PANAMA AND UPPER LEVEL DIFFLUENCE OVER CENTRAL AMERICA...SCATTERED SHOWERS AND TSTMS ARE OCCURRING IN THE SW CARIBBEAN WATERS...INCLUDING INTERIOR PORTIONS OF PANAMA AND COSTA RICA S OF 11N. ATLANTIC OCEAN... AN UPPER LEVEL TROUGH IS ACROSS THE SE CONUS WITH AN AREA OF UPPER LEVEL DIFFLUENCE TO ITS EAST GENERATING SCATTERED SHOWERS AND ISOLATED TSTMS ACROSS THE ERN FLORIDA PENINSULA COAST AND ALONG COASTAL GEORGIA AND SOUTH CAROLINA TO 79W. FARTHER TO THE E...AS HURRICANE BILL CONTINUES TO TRACK OFF TO THE N-NE OVER THE NEXT 24 HOURS...A RIDGE OF HIGH PRESSURE EXTENDS ACROSS THE REMAINDER OF THE SW NORTH ATLC. THIS RIDGE IS ANCHORED BY A 1025 MB HIGH CENTERED N OF THE AREA NEAR 37N51W WITH THE RIDGE ALONG 32N56W 25N65W TO ANDROS ISLAND IN THE NW BAHAMAS. THIS RIDGE IS FURTHER SUPPORTED BY AN UPPER LEVEL ANTICYCLONIC CIRCULATION CENTERED N OF PUERTO RICO NEAR 20N67W THAT IS PROMOTING WIDESPREAD SUBSIDENCE AND FAIR WEATHER. AN UPPER LEVEL LOW IS CENTERED NEAR 26N52W. ATMOSPHERIC LIFT AND MID-LEVEL INSTABILITY ARE GENERATING SCATTERED SHOWERS WITHIN 120 NM EITHER SIDE OF A LINE FROM 29N48W TO 20N58W. THE REMAINDER OF THE CENTRAL AND ERN ATLC ARE DOMINATED BY SURFACE RIDGING ANCHORED BY A 1024 MB HIGH CENTERED E OF THE AZORES NEAR 37N23W. $$ HUFFMAN