000 AXNT20 KNHC 092344 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SUN SEP 09 2012 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...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL ANALYSIS. BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2245 UTC. ...SPECIAL FEATURES... HURRICANE MICHAEL IS CENTERED NEAR 33.6N 423.8W AT 09/2100 UTC OR ABOUT 860 NM WSW OF THE AZORES MOVING W AT 04 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 978 MB. MAXIMUM SUSTAINED WIND SPEED IS 80 KT WITH GUSTS TO 100 KT. SCATTERED MODERATE CONVECTION IS FROM 31N-34N BETWEEN 41W-45W. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT3/WTNT23 KNHC FOR MORE DETAILS. TROPICAL STORM LESLIE IS CENTERED NEAR 33.8N 62.0W AT 10/0000 UTC OR ABOUT 165 NM ENE OF BERMUDA MOVING N AT 12 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 988 MB. MAXIMUM SUSTAINED WIND SPEED IS 50 KT WITH GUSTS TO 60 KT. NUMEROUS MODERATE/SCATTERED STRONG CONVECTION IS FROM 31N-33N BETWEEN 61W-65W...FROM 33N-35N BETWEEN 60W-62W...AND FROM 33N-34N BETWEEN 63W-65W. SCATTERED MODERATE CONVECTION IS ELSEWHERE FROM 34N-38N BETWEEN 60W-65W. SEE LATEST NHC INTERMEDIATE PUBLIC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT2/WTNT32 AND THE FULL FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC FOR MORE DETAILS. TROPICAL WAVE EXTENDS FROM 23N31W TO A 1009 MB SURFACE LOW AT 13N32W. THE WAVE/LOW ARE WITHIN A LARGE AREA OF DEEP MOISTURE WITH MAXIMUM VALUES NEAR THE WAVE/LOW CENTER EVIDENT IN TOTAL PRECIPITABLE WATER IMAGERY. MID/LOW-LEVEL CYCLONIC FLOW IS EVIDENT IN SATELLITE IMAGERY AND SATELLITE DERIVED WINDS. SCATTERED MODERATE/STRONG CONVECTION IS MAINLY WEST OF THE AXIS FROM 15N-19N BETWEEN 31W-35W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 10N-12N BETWEEN 28W-36W. ENVIRONMENTAL CONDITIONS APPEAR CONDUCIVE FOR GRADUAL DEVELOPMENT AS THE LOW/WAVE MOVE WESTWARD AT ABOUT 20 KT. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ACROSS W AFRICA TO THE COAST OF SENEGAL AT 15N17W CONTINUING ACROSS ATLC WATERS TO A SURFACE LOW ATTACHED TO A TROPICAL WAVE AT 13N32W. IT THEN CONTINUES ALONG 10N42W 10N52W. THE ITCZ BEGINS AT 10N52W TO 11N61W. A NEGATIVELY TILTED SURFACE TROUGH IS WEST OF THE TROPICAL WAVE ALONG 18N42W TO 13N36W. IT ALSO ALIGNS WITH A SURGE OF DEEP LAYER MOISTURE AND IS SUPPORTING SCATTERED MODERATE/ISOLATED STRONG CONVECTION WITHIN 100 NM WEST OF THE AXIS. THE TROUGH WILL REMAIN TILTED AND IS MOVING SLOWER THAN THE WAVE TO ITS EAST. THIS WILL EVENTUALLY CAUSE THE TWO FEATURES TO MERGE LATER IN THE WEEK. NO DEEP CONVECTION IS NOTED ELSEWHERE ALONG THE MONSOON TROUGH/ITCZ. ...DISCUSSION... GULF OF MEXICO... A WEAK COLD FRONT CONTINUES TO MOVE THROUGH THE GULF OF MEXICO CURRENTLY EXTENDING FROM NORTHERN FLORIDA NEAR 29N82W TO SOUTH OF THE SOUTHERN TIP OF TEXAS AT 23N98W CONTINUING INTO MEXICO TO 26N103W...AS OF 2100 UTC. ISOLATED SHOWERS/THUNDERSTORMS EXTEND UP TO 150 NM SE OF THE AXIS AND WITHIN 90 NM NW OR BEHIND THE FRONT. THE FRONT IS SUPPORTED BY A LONGWAVE UPPER TROUGH OVER THE EASTERN CONUS. STRONG DRY AIR AND SUBSIDENCE ARE ALSO BEHIND THE FRONT...WHICH IS LEAVING THE NORTHERN GULF COAST UNDER VERY CLEAR SKIES. THE SOUTHERN GULF IS ALSO EXPERIENCING MOSTLY FAIR CONDITIONS DUE TO DRY AIR ALOFT AROUND A WEAK UPPER RIDGE EXTENDING FROM THE SW GULF TO CENTRAL FLORIDA. IT SUPPORTS WEAK SURFACE RIDGING CROSS THIS AREA AND VERY LIGHT WINDS. WINDS ARE HIGHER IMMEDIATELY AHEAD AND BEHIND THE FRONT. THE UPPER TROUGH SUPPORTING THE FRONT IS EXPECTED TO MOVE MAINLY EAST...BUT NOT MUCH FARTHER SOUTH. THE FRONT IS EXPECTED TO SLOWLY DRIFT SOUTH BEFORE BECOMING STATIONARY ACROSS CENTRAL FLORIDA AND THEN WILL GRADUALLY DISSIPATE OVER THE NEXT COUPLE OF DAYS. ISOLATED SHOWERS/THUNDERSTORMS WILL BE LIKELY NEAR THE AXIS. CARIBBEAN SEA... A SIMILAR PATTERN AS YESTERDAY RESIDES ACROSS THE CARIBBEAN WITH MOSTLY CLEAR SKIES AND FAIR CONDITIONS COVERING A GOOD PORTION OF THE BASIN. THIS IS THE RESULT OF DRY AIR ALOFT AROUND AN UPPER LEVEL RIDGE IN THE W ATLC. HOWEVER...AN INVERTED UPPER TROUGH OVER THE NW CARIBBEAN IS HELPING PRODUCE SOME SHOWERS/THUNDERSTORMS ACROSS HONDURAS AND GUATEMALA. SIMILAR ACTIVITY IS ALSO ACROSS NICARAGUA AND COSTA RICA...BUT SOME OF THIS ACTIVITY MAY BE MORE ASSOCIATED WITH THE MONSOON TROUGH EXTENDING THROUGH COAST RICA AND PANAMA TO A 1007 MB SURFACE LOW OVER NORTHERN COLOMBIA. TRADEWIND FLOW OF 15-20 KT IS ACROSS THE MAJORITY OF THE BASIN WITH LIGHTER WINDS IN BOTH THE FAR EASTERN AND FAR WESTERN CARIBBEAN. EXPECT LITTLE CHANGE OVER THE NEXT 24 HOURS. ATLANTIC OCEAN... THE COLD FRONT ACROSS THE GULF OF MEXICO IS BEGINNING TO EMERGE OVER THE W ATLC WATERS FROM A FRONTAL LOW AT 33N77W TO NE FLORIDA AT 30N81W. ISOLATED SHOWERS/THUNDERSTORMS ARE WITHIN 175 NM SE...AND 90 NM NW OF THE AXIS. THE FRONT IS SUPPORTED BY A LONGWAVE UPPER TROUGH OVER THE EASTERN CONUS. AN UPPER LEVEL RIDGE COVERS THE REMAINDER OF THE WEST ATLC ACCOMPANIED BY DRY AIR ALOFT. IT SUPPORTS WEAK SURFACE RIDGING ACROSS THE CENTRAL ATLC INTO THE W ATLC S OF THE CIRCULATION OF LESLIE. A WEAK SPOT HIGH IS AT 20N61W. FAIR WEATHER IS PRESENT AROUND THE SURFACE RIDGE. TO THE N...TROPICAL STORM LESLIE IS MOVING PAST BERMUDA WITH HURRICANE MICHAEL WELL TO THE EAST. SEE THE SPECIAL FEATURES SECTION FOR MORE DETAILS ON THESE STORMS. A NARROW UPPER LEVEL TROUGH EXTENDS FROM SOUTH OF MICHAEL TOWARDS THE LESSER ANTILLES...BUT IS NOT CAUSING ANY ACTIVE WEATHER. IT IS SQUISHED BETWEEN THE UPPER RIDGE TO THE WEST OVER THE WEST ATLC...AND AN UPPER LEVEL RIDGE COVERING THE EAST ATLC CENTERED NEAR 23N32W. THE UPPER RIDGE SUPPORTS A 1023 MB SURFACE HIGH AT 31N27W...WHICH IS PROVIDING FAIR WEATHER BESIDES NEAR A TROPICAL WAVE AND TROUGH IN THE TROPICAL ATLC. THE LAST VISIBLE SATELLITE IMAGERY OF THE DAY ALONG WITH GOES-R ENHANCEMENT IMAGERY INDICATES AN AREA OF AFRICAN DUST HAS EMERGED OFF THE COAST OF AFRICA BEHIND THE TROPICAL WAVE. THE DUST EXTENDS TO ABOUT 30W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ WALTON