000 AXNT20 KNHC 112354 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SUN OCT 11 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 2230 UTC. ...TROPICAL WAVES... ATLANTIC TROPICAL WAVE EXTENDS FROM 17N40W TO 6N42W MOVING W NEAR 10 KT. SATELLITE IMAGERY AND SATELLITE DERIVED WINDS INDICATE LOW-LEVEL CYCLONIC FLOW IN THE VICINITY OF THE WAVE AXIS. THE WAVE ALSO LEADS A MAXIMUM IN DEEP LAYER MOISTURE OBSERVED IN TOTAL PRECIPITABLE WATER IMAGERY. NO DEEP CONVECTION IS CURRENTLY ASSOCIATED WITH THE WAVE. HOWEVER...ISOLATED SHOWERS ARE FROM 11N-16N BETWEEN 40W-43W. CARIBBEAN TROPICAL WAVE IS ALONG 78W S OF 18N MOVING W NEAR 15 KT. SATELLITE IMAGERY AS WELL AS AN ASCAT SCATTEROMETER PASS FROM EARLIER TODAY INDICATE BROAD LOW-LEVEL CYCLONIC FLOW ACROSS THE CENTRAL CARIBBEAN CONCENTRATED NEAR THE WAVE AXIS. THE WAVE ALSO COINCIDES WITH A DEEP LAYER MOISTURE MAXIMUM OBSERVED IN TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 10N-14N BETWEEN 78W-82W...AND FROM 17N-19N BETWEEN 76W-80W. ...THE ITCZ... THE ITCZ AXIS IS CENTERED ALONG 10N14W 7N23W 10N32W 14N40W 6N58W. SCATTERED MODERATE CONVECTION IS ALONG THE AFRICA COAST FROM 6N-8N BETWEEN 11W-14W. ISOLATED MODERATE CONVECTION IS FROM 10N-12N BETWEEN 12W-15W. SIMILAR ACTIVITY IS WITHIN 100 NM N OF THE AXIS BETWEEN 44W-49W ...DISCUSSION... THE GULF OF MEXICO... AS OF 2100 UTC...A STATIONARY FRONT CROSSES N FLORIDA FROM NEAR ST. AUGUSTINE AT 30N81W ENTERING THE GULF OF MEXICO NEAR 30N83W CONTINUING TO 28N89W WHERE IT HAS BEGUN TO MOVE NWD AS A WARM FRONT ALONG 28N95W 27N97W 23N97W INTO MEXICO TO 23N99W WHERE IT AGAIN BECOMES STATIONARY ALONG THE E SLOPES OF THE SIERRA MADRE MOUNTAINS. SCATTERED SHOWERS/THUNDERSTORMS ARE N OF 28N BETWEEN 88W-92W AFFECTING PORTIONS OF MISSISSIPPI AND LOUISIANA. SIMILAR ACTIVITY IS ALSO OFF THE TEXAS COAST FROM 26N-28N BETWEEN 94W-96W...AND FROM 20N-24N BETWEEN 94W-97W OFF THE COAST OF MEXICO. THE REMAINDER OF THE GULF IS EXPERIENCING GENERALLY FAIR WEATHER THIS EVENING UNDER THE INFLUENCE OF MODERATELY DRY AIR AND SUBSIDENCE ALOFT DUE TO AN UPPER LEVEL RIDGE CENTERED OVER THE GULF OF MEXICO NEAR 26N86W. EXPECT A SURFACE RIDGE TO BUILD ACROSS THE GULF AS THE FRONTAL SYSTEM CONTINUES TO LIFT NW TONIGHT. THE CARIBBEAN SEA... A TROPICAL WAVE ALONG 78W IS THE MAIN SURFACE FEATURE ACROSS THE CARIBBEAN. SEE ABOVE. A SURFACE TROUGH...REMNANTS OF HENRI...EXTENDS ACROSS THE WINDWARD PASSAGE FROM 22N72W TO 18N74W. ISOLATED SHOWERS/THUNDERSTORMS ARE WITHIN 100 NM OF THE TROUGH AXIS AFFECTING WRN HISPANIOLA AND ERN CUBA. ISOLATED SHOWERS/THUNDERSTORMS ARE ALSO N OF 16N BETWEEN 64W-70W. IN THE UPPER LEVELS...DRY AIR AND SUBSIDENCE IN ELY FLOW ALOFT COVER THE CARIBBEAN E OF 80W. AN UPPER LEVEL RIDGE EXTENDING FROM THE GULF OF MEXICO COVERS THE BASIN W OF 80W. MODERATE WINDS ARE ACROSS MUCH THE BASIN BECOMING FRESH IN THE SW AND ERN CARIBBEAN. EXPECT THE TROPICAL WAVE ALONG 78W TO CONTINUE WWD. THE ATLANTIC OCEAN... A STATIONARY FRONT ENTERS THE AREA NEAR 31N77W CONTINUING TO THE FLORIDA COAST NEAR ST AUGUSTINE CONTINUING INTO THE GULF OF MEXICO. THE FRONT IS SUPPORTING ISOLATED SHOWERS/THUNDERSTORMS ACROSS THE FLORIDA PENINSULA N OF 26N. BROAD SURFACE HIGH PRESSURE COVERS MUCH OF THE WRN BASIN ANCHORED BY A 1020 MB HIGH NEAR 30N68W. THE SURFACE HIGH IS SUPPORTED BY AN UPPER LEVEL RIDGE BETWEEN 40W-75W CENTERED NEAR 25N66W. A SURFACE TROUGH...REMNANTS OF HENRI...IS THE FAR SW ATLC EXTENDING ACROSS THE WINDWARD PASSAGE 22N72W TO 18N74W. MOST OF THE SHOWER ACTIVITY ASSOCIATED WITH THE TROUGH IS S OF 21N IN THE CARIBBEAN. A COLD FRONT ENTERS THE ERN ATLC NEAR 32N27W EXTENDING ALONG 25N32W 21N40W 18N50W CONTINUING AS A SURFACE TROUGH TO 19N64W. SCATTERED SHOWERS/THUNDERSTORMS ARE WITHIN 200 NM BEHIND...AND 100 NM AHEAD OF THE FRONT N OF 23N. ISOLATED SHOWERS ARE ALSO FROM 21N-26N BETWEEN 33W-36W...AND ALONG THE SURFACE TROUGH BETWEEN 56W-64W. THE FRONTAL SYSTEM IS SUPPORTED BY AN UPPER LEVEL TROUGH WITH AXIS ALONG 33W. AN UPPER LEVEL RIDGE CENTERED NEAR 10N20W DOMINATES THE ERN TROPICAL ATLC. $$ WALTON