000 AXNT20 KNHC 300004 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT MON AUG 29 2011 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 2345 UTC. ...SPECIAL FEATURE... T.D. TWELVE IS CENTERED NEAR 10.2N 28.4W AS OF 29/2100 UTC...OR ABOUT 360 NM SW OF THE SOUTHERNMOST CAPE VERDE ISLANDS MOVING W AT 13 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1008 MB. MAXIMUM SUSTAINED WIND SPEED IS 30 KT WITH GUSTS TO 40 KT. PLEASE SEE THE LATEST INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADER MIATCPAT2/WTNT32 KNHC AND THE FULL FORECAST/ADVISORY UNDER AWIPS/WMO HEADER MIATCMAT2/WTNT22 KNHC FOR MORE DETAILS. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS MOSTLY W OF THE CENTER FROM 8N-14N BETWEEN 29W-35W. ENVIRONMENTAL CONDITIONS ARE CONDUCIVE FOR GRADUAL INTENSIFICATION OF THIS SYSTEM OVER THE NEXT COUPLE OF DAYS. ...THE ITCZ/THE MONSOON TROUGH... THE MONSOON TROUGH IS ANALYZED ACROSS AFRICA AND BARELY ENTERS THE E TROPICAL ATLC THROUGH THE COAST OF MAURITANIA NEAR 19N16W TO 18N18W. THE BROAD CYCLONIC WIND FIELD ASSOCIATED TO T.D. TWELVE HAS DISRUPTED THE OCEANIC MONSOON TROUGH...ONLY ALLOWING A SMALL PORTION OF ITCZ TO REDEVELOPED FROM 10N45W TO 10N58W. ISOLATED MODERATE CONVECTION IS WITHIN 60 NM OF THE ITCZ AXIS BETWEEN 50W AND 56W. THE MONSOON TROUGH FROM THE NORTHEAST PACIFIC CURRENTLY EXTENDS ACROSS CENTRAL AMERICA AND ENTERS THE CARIBBEAN NEAR 11N83W TO THE COAST OF COLUMBIA AT 09N76W. MODERATE CONVECTION IS OCCURRING WITHIN 120 NM OF THE TROUGH AXIS. ...DISCUSSION... GULF OF MEXICO... AS OF 2100 UTC...A DISSIPATING STATIONARY FRONT IS DRAPED ACROSS THE NORTH CENTRAL GULF OF MEXICO. WINDS ARE LIGHT AND VARIABLE OVER THE CENTRAL AND WESTERN PORTIONS OF THE GULF THIS EVENING...WHILE THE EASTERN GULF SHOWS SW WINDS OF 10-15 KT ON THE EQUATORWARD SIDE OF THE FRONT. OVER THE YUCATAN OF MEXICO AND EXTENDING NORTHWARD JUST SLIGHTLY INTO THE SOUTHERN GULF OF MEXICO IS A SURFACE TROUGH. SCATTERED MODERATE CONVECTION IS OCCURRING OVER THE STRAITS OF FLORIDA...SOUTHERN FLORIDA...AND THE YUCATAN OF MEXICO. THE TOTAL PRECIPITABLE WATER IMAGERY INDICATES SUBSTANTIAL MOISTURE IN THE SOUTHERN TWO-THIRDS OF THE GULF...LIKELY ENHANCING THE AFOREMENTIONED CONVECTION. THE COMBINATION OF SURFACE RIDGING BECOMING MORE ESTABLISHED NORTHEAST OF FLORIDA AND PERSISTENCE OF THE TROUGH OVER YUCATAN...SHOULD LEAD TOWARD EASTERLY SURFACE WINDS PREVAILING DURING THE NEXT DAY OR TWO ALONG WITH INCREASED CHANCES FOR PRECIPITATION NEAR THE TROUGH. IN THE UPPER LEVELS...A SHARP NE-SW TROUGH IS LOCATED OVER THE GULF IN ASSOCIATION WITH THE FRONTAL BOUNDARY. SOUTH OF THE TROUGH AXIS...SOME UPPER LEVEL MOISTURE IS BEING ADVECTED NORTHEASTWARD ACROSS THE GULF AND THE FLORIDA PENINSULA. CARIBBEAN SEA... EASTERLY TRADEWINDS OF 15-20 KT IN THE EASTERN AND CENTRAL CARIBBEAN CONVERGING WITH WEAKER TRADES IN THE WESTERN CARIBBEAN ARE CONTRIBUTING TOWARD A WIDESPREAD AREA OF MODERATE CONVECTION IN THE CENTRAL AND WESTERN CARIBBEAN. WHILE THERE DOES NOT APPEAR TO BE A COHERENT SURFACE FEATURE ASSOCIATED WITH THIS CONVECTION...AN UPPER LOW CENTERED OVER HISPANIOLA MAY ALSO BE ENHANCING THE CONVECTIVE ACTIVITY. DURING THE NEXT DAY OR TWO...THE CONVERGENCE LINE...AND THUS THE CONVECTION...MAY SHIFT WESTWARD AND BECOME ASSOCIATED MORE WITH THE AFOREMENTIONED TROUGH OVER THE YUCATAN. THUS GENERALLY DRIER CONDITIONS OVER THE EASTERN AND CENTRAL CARIBBEAN AND A HIGHER CHANCE OF PRECIPITATION OVER THE WESTERN CARIBBEAN DURING THE NEXT COUPLE DAYS. ATLANTIC OCEAN... THE MAIN FEATURE OF INTEREST IS T.D. TWELVE IN THE EASTERN ATLANTIC. SEE EARLIER DISCUSSION OF THIS SYSTEM. ELSEWHERE TWO PROMINENT SURFACE TROUGHS ARE EVIDENT...ONE EXTENDING FROM 17N40W TO 26N37W AND A SECOND ONE FROM 27N51W TO 28N46W TO 30N40W. THE FIRST...THE REMNANTS OF T.D. 10...SHOWED A BRIEF FLAREUP OF MODERATE TO STRONG CONVECTION EAST OF THE TROUGH AXIS...BUT NOW ONLY HAS MODERATE CONVECTION WITHIN 180 NM WEST OF THE TROUGH AXIS SOUTH OF 18N. THERE MAY BE AN EXTENSION OF THIS TROUGH WESTWARD...THOUGH THIS IS NOT CURRENTLY SHOWN IN THE 18 UTC MAP. THE SECOND TROUGH HAS NO SIGNIFICANT DEEP CONVECTION CURRENTLY. ELSEWHERE...WIDESPREAD SHOWERS AND ISOLATED MODERATE CONVECTION IS OCCURRING NORTH OF 25N BETWEEN THE FLORIDA PENINSULA AND 60W...THOUGH NO SIGNIFICANT SURFACE FEATURE IS ASSOCIATED WITH THESE SHOWERS AND CONVECTION. EXCEPT FOR SOME 20 KT SURFACE WINDS NEAR THE COAST OF WEST AFRICA AND THE CIRCULATION AROUND T.D. TWELVE...THE TRADEWINDS ARE QUITE WEAK ACROSS THE TROPICAL NORTH ATLANTIC TODAY. THIS SHOULD CONTINUE FOR THE NEXT DAY OR TWO AS THE SURFACE HIGH NORTH OF THE AREA REMAINS RELATIVELY WEAK. IN THE UPPER LEVELS...A RATHER STRONG RIDGE ALONG 18N PROVIDING EASTERLY FLOW ACROSS THE ATLANTIC ON THE EQUATORWARD SIDE. ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ LANDSEA