000 AXNT20 KNHC 240000 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT THU AUG 23 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 2345 UTC. ...SPECIAL FEATURES... TROPICAL STORM ISAAC IS LOCATED NEAR 16.2N 67.8W AT 24/0000 UTC...MOVING WNW AT 14 KT. THIS POSITION IS ABOUT ABOUT 210 MI...340 KM SE OF SANTO DOMINGO DOMINICAN REPUBLIC. THE MINIMUM CENTRAL PRESSURE IS 1002 MB. THE MAXIMUM SUSTAINED WIND SPEEDS ARE 40 KT WITH GUSTS TO 50 KT. PLEASE READ THE FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/ WTNT24 KNHC AND THE PUBLIC ADVISORY...MIATCPAT4/WTNT34 KNHC FOR MORE DETAILS. SCATTERED MODERATE TO STRONG CONVECTION IS FROM 12N-22N BETWEEN 62W-72W. TROPICAL STORM JOYCE WAS LOCATED IN THE TROPICAL CENTRAL ATLC NEAR 15.9N 42.5W AT 23/2100 UTC...MOVING WNW AT 12 KNOTS. THE ESTIMATED MINIMUM CENTRAL PRESSURE WAS 1006 MB. THE MAXIMUM SUSTAINED WIND SPEEDS ARE 35 KT WITH GUSTS TO 45 KT. PLEASE READ THE FORECAST/ ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT5/WTNT25 KNHC AND THE PUBLIC ADVISORY...MIATCPAT5/WTNT35 KNHC FOR MORE DETAILS. JOYCE IS EXPERIENCING SOUTHERLY WIND SHEAR AND AN INTRUSION OF DUSTY DRY AIR. SCATTERED MODERATE TO STRONG CONVECTION IS MOSTLY N OF THE CENTER FROM 17N-23N BETWEEN 41W-48W. ...TROPICAL WAVES... A TROPICAL WAVE IS OVER THE ERN TROPICAL ATLC EXTENDING FROM THE COAST OF MAURITANIA NEAR 20N16W TO A 1010 MB LOW OFF THE COAST OF SENEGAL NEAR 14N20W. THIS SYSTEM IS MOVING WSW AT 5-10 KT. A THICK LAYER OF SAHARAN DUST SURROUNDS THE WAVE AND ASSOCIATED LOW...INHIBITING THIS SYSTEM TO GENERATE CONVECTION. AN AREA OF SCATTERED SHOWERS AND THUNDERSTORMS IS WELL TO THE S FROM 8N-11N BETWEEN 18W-29W. ...THE ITCZ/THE MONSOON TROUGH... THE OCEANIC ITCZ AND MONSOON TROUGH ARE PRESENTLY BEING DISRUPTED BY THE BROAD CYCLONIC WIND FIELD FROM TROPICAL WAVE AND ASSOCIATED LOW OFF THE CAST OF SENEGAL AND TROPICAL STORM JOYCE. ...DISCUSSION... THE GULF OF MEXICO... UPPER LEVEL CYCLONIC FLOW COVERS THE BASIN...AS THE BASE OF AN UPPER TROUGH MOVES ACROSS THE REGION. THIS FEATURE IS PROVIDING STRONG DIFFLUENCE ALOFT OVER THE NW QUADRANT OF THE BASIN... GENERATING AN AREA OF SCATTERED SHOWERS AND THUNDERSTORMS N OF 24N W OF 90W. ISOLATED WEAK SHOWERS REMAIN OVER THE WRN BAY OF CAMPECHE TO THE COASTAL WATERS OF TAMPICO FROM A TROPICAL WAVE NOW DISSIPATED OVER THE SIERRA MADRE MOUNTAINS. THE REMAINDER OF THE GULF BASIN IS DOMINATED BY A 1020 MB HIGH CENTERED IN THE NW COAST OF THE FLORIDA PENINSULA NEAR 29N83W. WHILE WINDS ARE LIGHT AND VARIABLE OVER THE NE BASIN AND NEAR THE HIGH PRESSURE CENTER...SSE WINDS UP TO 15 KT ARE FOUND ELSEWHERE S OF 25N W OF 87W. EXPECT CONTINUED CONVECTION OVER THE NW GULF DURING THE NEXT 24 HOURS. THE CARIBBEAN SEA... TROPICAL STORM ISAAC CONTINUES TO BE THE MAIN WEATHER PRODUCER IN THE CARIBBEAN SEA...GENERATING CONSIDERABLE CONVECTION OVER THE ERN BASIN. SEE SPECIAL FEATURES SECTION ABOVE FOR MORE INFORMATION ON THIS SYSTEM. ASIDE ISAAC...THE REMAINDER OF THE CARIBBEAN IS DOMINATED BY DRY AIR AND SUBSIDENCE ALOFT WRAPPED AROUND AN ELONGATED UPPER LEVEL LOW CENTERED NEAR 20N78W. ISAAC WILL CONTINUE TO AFFECT THE CENTRAL AND EASTERN CARIBBEAN OVER THE NEXT 24 HOURS. THE ATLANTIC OCEAN... THE OUTER CONVECTION BANDS ASSOCIATED TO TROPICAL STORM ISAAC ARE CURRENTLY AFFECTING THE NRN COASTAL WATERS OF PUERTO RICO...HISPANIOLA...AND TURKS AND CAICOS. SEE SPECIAL FEATURES SECTION ABOVE FOR MORE INFORMATION ON THIS SYSTEM. ASIDE TROPICAL STORMS JOYCE AND ISAAC...THE ATLC BASIN DISCUSSION AREA IS DOMINATED BY A BROAD SURFACE RIDGE ANCHORED BY A 1023 MB HIGH IN THE ERN BASIN NEAR 37N52W...A 1024 MB HIGH IN THE CENTRAL BASIN NEAR 33N40W...AND A 1021 MB HIGH IN THE ERN BASIN NEAR 35N22W. THE FAIR WEATHER IS ENHANCED ALOFT BY SAHARAN DUST NOTED ON METEOSAT-9 PRODUCT. EMBEDDED IN THIS DRY ENVIRONMENT...AN UPPER LOW WOBBLES NEAR 21N51W. THE CONVECTION ASSOCIATED TO JOYCE IS EXPECTED TO TRACK NW INTO THE SUBTROPICAL CENTRAL ATLC N OF 25N OVER THE NEXT 24 HOURS. ALSO...EXPECT WEATHER CONDITIONS TO DETERIORATE OVER THE NRN COASTAL WATERS OF PUERTO RICO...HISPANIOLA...TURKS AND CAICOS...AND THE SE BAHAMAS DURING THE FORECAST PERIOD AS TROPICAL STORM ISAAC APPROACHES THE SRN BORDER BETWEEN HAITI AND DOMINICAN REPUBLIC. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ GARCIA