000 AXNT20 KNHC 161751 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT SUN SEP 16 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1745 UTC. ...SPECIAL FEATURE... HURRICANE NADINE IS CENTERED NEAR 30.5N 41.7W 16/1500 UTC OR ABOUT ABOUT 985 MI...1585 KM WSW OF THE AZORES. NADINE IS MOVING E AT 20 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 983 MB. MAXIMUM SUSTAINED WIND SPEED IS 70 KT WITH GUSTS TO 85 KT. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/ WTNT24 KNHC FOR MORE DETAILS. MODERATE TO STRONG CONVECTION FROM 27N-34N BETWEEN 36W-42W. ...TROPICAL WAVES... TROPICAL WAVE MOVES ACROSS THE ERN TROPICAL ATLC WITH AXIS EXTENDING FROM WEST OF THE CAPE VERDE ISLANDS NEAR 17N27W TO 9N29W MOVING W AT 10-15 KT. THIS WAVE ALIGNS WITH A SMALL SURGE OF DEEP LAYER MOISTURE PRESENT IN TOTAL PRECIPITABLE WATER IMAGERY. HOWEVER...THIS WAVE IS EMBEDDED IN DRY SAHARAN AIR. NO DEEP CONVECTION IS CURRENTLY ASSOCIATED WITH THE WAVE. TROPICAL WAVE APPROACHES THE LESSER ANTILLES ANALYZED FROM 18N55W TO 11N54W MOVING W AT 10-15 KT. A 1011 MB SURFACE LOW IS EMBEDDED ALONG THE WAVE AXIS NEAR 13N55W. THE WAVE LIES WITHIN AN AREA OF MAXIMUM MOISTURE EVIDENT IN TOTAL PRECIPITABLE WATER IMAGERY. THE CONVECTION ASSOCIATED TO THIS SYSTEM IS WELL TO THE W OF THE ANALYZED FEATURE AFFECTING THE ERN CARIBBEAN AND LESSER ANTILLES FROM GUADELOUPE S TO GRENADA BETWEEN 55W-63W. LOCALLY HEAVY RAINS AND SQUALLS COULD AFFECT PORTIONS OF THE NRN LESSER ANTILLES TODAY THROUGH AND MONDAY. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH AXIS IS ANALYZED FROM THE COAST OF GUINEA NEAR 10N14W ALONG 11N21W 9N27W 10N32W TO 8N39W...WHERE THE ITCZ AXIS CONTINUES TO 11N47W. SCATTERED MODERATE CONVECTION FROM 5N-11N BETWEEN 35W-45W...AS WELL AS FROM 5N-10N BETWEEN 20W AND THE COAST OF WEST AFRICA. ...DISCUSSION... GULF OF MEXICO... A WEAK UPPER LEVEL TROUGH MOVES ACROSS THE ERN GULF ON WATER VAPOR IMAGERY. DOPPLER RADAR IMAGERY SHOWS THIS UPPER FEATURE IS GENERATING CLUSTERS OF SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS OVER THE WRN COASTAL WATERS OF THE FLORIDA PENINSULA AND STRAITS E OF 84W S OF 28N. SHORT RAGE COMPUTER MODELS KEEP THE CONVECTION IN THIS REGION DURING THE NEXT 12 HOURS...DRIFTING N ACROSS THE FLORIDA PANHANDLE OVER THE NEXT 12-24 HOURS. A SURFACE TROUGH IS ANALYZED OVER THE NW BASIN FROM NEAR THE COAST OF TEXAS AT 27N96W TO 22N94W...PRODUCING SIMILAR CONVECTION W OF 90W FROM 24W-28W. THE SURFACE TROUGH IS EXPECTED TO DRIFT WNW AND WILL EVENTUALLY BE ABSORBED BY A FRONTAL BOUNDARY THAT WILL REACH THE NW BASIN OVER THE NEXT 24 HOURS. MOIST CONDITIONS AND BROAD SURFACE TROUGHING WILL REMAIN ACROSS THE BASIN DURING THE FORECAST PERIOD. CARIBBEAN SEA... A TROPICAL WAVE AND ASSOCIATED LOW PRESSURE SYSTEM LOCATED E OF THE LESSER ANTILLES IS GENERATING SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS OVER THE ERN CARIBBEAN ISLANDS FROM GUADELOUPE S TO GRENADA. THIS AREA OF MODERATE TO STRONG CONVECTION WILL SLOWLY MOVE NNW ACROSS THE NRN LEEWARD ISLANDS AND ADJACENT WATERS DURING THE NEXT 24 HOURS. THE REMAINDER OF THE DISCUSSION AREA IS UNDER FAIR WEATHER CONDITIONS RELATED TO DRY AIR ALOFT AROUND AN UPPER LEVEL RIDGE CENTERED IN THE NW CARIBBEAN...AND A DRY INVERTED UPPER TROUGH MOVING ACROSS THE CENTRAL CARIBBEAN. THE ENVIRONMENT ALOFT IS SUPPRESSING DEEP CONVECTION AND ONLY ALLOWING FOR A FEW ISOLATED SHOWERS OVER THE COASTAL WATERS OF HONDURAS...NICARAGUA...AND PANAMA. THE SHOWER ACTIVITY IN THESE AREAS ARE RELATED TO THE ERN PACIFIC MONSOON TROUGH EXTENDING ACROSS COSTA RICA TO NRN COLOMBIA. ATLANTIC OCEAN... A WEAK UPPER LEVEL TROUGH MOVING ACROSS THE ERN GULF OF MEXICO IS GENERATING SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS W OF THE NW BAHAMAS TO OVER THE FLORIDA PENINSULA AND STRAITS S OF 27N W OF 78W...EXPECTED TO LINGER AROUND THE SAME REGION DURING THE NEXT 24 HOURS. AN UPPER LEVEL TROUGH IS NOTED ON WATER VAPOR IMAGERY MOVING ACROSS THE WRN ATLANTIC ALONG 60W N OF THE DISCUSSION AREA. THIS FEATURE SUPPORTS A COLD FRONT EXTENDING INTO OUR AREA AS A SURFACE TROUGH ALONG 30N60W 24N65W TO THE SE BAHAMAS NEAR 21N73W. HOWEVER...THIS BOUNDARY IS MOSTLY EMBEDDED WITH DRY AIR KEEPING SHOWER ACTIVITY AT A MINIMUM. CURRENTLY... ISOLATED WEAK SHOWERS ARE NOTED WITHIN 60 NM ON EITHER SIDE OF THE AXIS. THIS BOUNDARY IS EXPECTED TO WEAKEN AND DISSIPATE DURING THE NEXT 24 HOURS...AS HIGH PRESSURE BUILDS IN ITS WAKE THROUGH TUESDAY. TROPICAL STORM NADINE IS OVER THE CENTRAL ATLC. SEE SPECIAL FEATURE ABOVE FOR MORE DETAILS ON NADINE. THE REMAINDER OF THE ATLC BASIN DISCUSSION AREA IS DOMINATED BY A SURFACE RIDGE OF HIGH PRESSURE ANCHORED BY A 1018 MB HIGH NEAR 25N30W. THE OVERALL FAIR WEATHER IS ENHANCED ALOFT BY THICK LAYER OF SAHARAN DUST NOTED ON METEOSAT-9 SAL PRODUCT E OF 40W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ GARCIA