000 AXNT20 KNHC 302353 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT WED SEP 30 2015 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 2315 UTC. ...SPECIAL FEATURES... JOAQUIN BECAME A HURRICANE THIS MORNING AND CONTINUES TO STRENGTHEN JUST E OF THE BAHAMAS. IT IS CENTERED NEAR 24.3N 73.1W AT 30/2100Z OR ABOUT 190 MI...305 KM ENE OF THE CENTRAL BAHAMAS MOVING TOWARD THE SOUTHWEST OR 225 DEGREES AT 7 KT. ON THE FORECAST TRACK...THE CENTER OF JOAQUIN IS EXPECTED TO MOVE NEAR OR OVER PORTIONS OF THE CENTRAL BAHAMAS TONIGHT AND THU. MAXIMUM SUSTAINED WIND SPEED IS 75 KT WITH GUSTS TO 90 KT. NUMEROUS STRONG CONVECTION IS WITHIN 90 NM OF CENTER...EXCEPT SW QUADRANT. NUMEROUS MODERATE ISOLATED STRONG CONVECTION IS NOTED ELSEWHERE FROM 21N-26N BETWEEN 70W-75W. PART OF THE CONVECTION ASSOCIATED WITH THE OVERALL CIRCULATION OF JOAQUIN IS AFFECTING THE SE BAHAMAS AND THE TURKS AND CAICOS ISLANDS AS WELL AS EASTERN CUBA. JOAQUIN IS EXPECTED TO PRODUCE 5-10 INCHES OF RAIN OVER MUCH OF THE CENTRAL BAHAMAS, WITH ISOLATED MAXIMUM AMOUNTS OF 20 INCHES POSSIBLE OVER SAN SALVADOR AND RUM CAY THROUGH FRI NIGHT. RAINFALL AMOUNTS OF 3-5 INCHES ARE POSSIBLE OVER SOUTHEASTERN BAHAMAS THROUGH FRI NIGHT...WITH 2-4 INCHES EXPECTED OVER THE NW BAHAMAS. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT1/WTNT21 KNHC FOR MORE DETAILS. A 1009 MB LOW PRES IS ANALYZED NEAR 25.5N 57.5W ALONG AN OLD FRONTAL TROUGH THAT EXTENDS FROM 25N51W TO THE LOW CENTER TO 27N64W. A LARGE AREA OF CLOUDINESS WITH EMBEDDED TSTMS IS NOTED MAINLY E OF THE LOW CENTER COVERING THE AREA FROM 24N-27N BETWEEN 54W-57W. THIS SYSTEM HAS BECOME A LITTLE BETTER ORGANIZED SINCE YESTERDAY..AND ADDITIONAL GRADUAL DEVELOPMENT IS POSSIBLE DURING THE NEXT SEVERAL DAYS WHILE IT MOVES SLOWLY NORTHWESTWARD TO NORTHWARD. THE LATEST NHC TROPICAL WEATHER OUTLOOK GIVES THIS LOW PRES AREA A MEDIUM CHANCE OF DEVELOPING INTO A TROPICAL CYCLONE DURING THE NEXT 48 HOURS. ...TROPICAL WAVES... A TROPICAL WAVE IS NEAR THE CAPE VERDE ISLANDS WITH AN AXIS EXTENDING FROM 19N22W TO 12N24W...MOVING SLOWLY W AT 5-10 KT. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS NOTED AHEAD OF THE WAVE AXIS FROM 12N-15N BETWEEN 23W-27W. THE WAVE IS WELL DEPICTED IN THE LATEST GFS 700 MB STREAMLINES AND 850 MB VORTICITY ANALYSIS...AND IS ALSO REFLECTED IN A SURGE OF MOISTURE ON THE TPW SATELLITE IMAGERY. A SECOND TROPICAL WAVE IS IN THE CENTRAL ATLANTIC EXTENDING FROM 18N37W TO 10N40W...MOVING W AT 5 KT. AN INVERTED-V PATTERN IS NOTED IN THE CLOUD FIELD. A SMALL CLUSTER OF MODERATE CONVECTION IS WHERE THE WAVE MEETS THE MONSOON TROUGH. TPW IMAGERY SHOWS THE WAVE EMBEDDED IN A MODERATE MOIST ENVIRONMENT. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE COAST OF AFRICA NEAR 14N17W TO 11N26W TO 12N38W TO 10N49W. THE ITCZ CONTINUES FROM 10N49W TO 11N55W TO 9N61W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS FROM 7N-11N BETWEEN 19.5W-22W. SCATTERED MODERATE IS FROM 10N- 11N BETWEEN 42W-46W. ...DISCUSSION... GULF OF MEXICO... A SHARP UPPER-LEVEL TROUGH IS OVER THE NW GULF EXTENDING FROM SE LOUISIANA TO NEAR BROWNSVILLE TEXAS. SW FLOW AHEAD OF THE TROUGH IS ADVECTING ABUNDANT MID TO UPPER-LEVEL MOISTURE FROM SOUTH- CENTRAL MEXICO ALL THE WAY NE TO BEYOND FLORIDA. THIS TROUGH SUPPORTS A WEAK 1009 MB LOW PRES LOCATED NEAR 26N92W WITH A TROUGH EXTENDING NE TO THE FLORIDA PANHANDLE. VISIBLE SATELLITE IMAGERY SHOWS A SWIRL OF LOW CLOUDS IN ASSOCIATION WITH THIS LOW FORECAST TO WEAKEN TO A TROUGH TONIGHT. AT 2100 UTC... SCATTEROMETER DATA INDICATE THE PRESENCE OF ANOTHER SURFACE TROUGH OVER THE SE GULF AND STRETCHES FROM 25N84W TO 22N87W TO THE NORTHERN YUCATAN PENINSULA NEAR 20N89W. THE TROUGH IS GENERATING SOME SHOWER AND TSTM ACTIVITY OVER PARTS OF WESTERN CUBA AND THE YUCATAN PENINSULA. LOOKING AHEAD...A COLD FRONT IS FORECAST TO REACH THE NORTHERN GULF BY THU. THIS FRONT WILL MOVE RAPIDLY SE AND EXTEND FROM TAMPA BAY TO THE BAY OF CAMPECHE EARLY FRI AFTERNOON...AND MOVE SE OF GULF BY EARLY SAT AS WEAKENING FRONT. FRESH TO STRONG NORTHERLY WINDS AND BUILDING SEAS ARE EXPECTED IN THE WAKE OF THE FRONT. CARIBBEAN SEA... DUE TO THE PRESENCE OF HURRICANE JOAQUIN JUST E OF THE BAHAMAS...MAINLY GENTLE TRADE WINDS ARE NOTED ACROSS THE BASIN WITH THE EXCEPTION OF MODERATE TRADE WINDS OVER THE SOUTH- CENTRAL CARIBBEAN. IN ADDITION...ANOMALOUS SW TO W WINDS ARE SEEN PER SCATTEROMETER DATA OVER MUCH OF THE NW CARIBBEAN... BETWEEN EASTERN CUBA AND JAMAICA AND INTO THE WINDWARD PASSAGE. AS JOAQUIN APPROACHES THE CENTRAL BAHAMAS TONIGHT AND THU...THE SW FLOW MAY INCREASE...PARTICULARLY ACROSS THE EASTERN HALF OF CUBA AND REGIONAL WATERS...INCLUDING ALSO THE WINDWARD PASSAGE. THE GFS COMPUTER MODEL SUGGESTS INCREASING WINDS TO 20-25 KT. AS IT IS NORMAL FOR THIS TIME OF THE YEAR...THE MONSOON TROUGH IS OVER THE FAR SOUTH-CENTRAL CARIBBEAN GENERATING SOME SHOWER AND TSTM ACTIVITY OVER PARTS OF PANAMA AND COSTA RICA. ALOFT... UPPER-LEVEL NLY FLOW PREVAILS OVER MOST OF THE CENTRAL AND WESTERN CARIBBEAN. AN UPPER-LEVEL TROUGH EXTENDS FROM THE LEEWARD ISLANDS TO THE ABC ISLANDS AND NW VENEZUELA. SW WINDS AHEAD OF THE TROUGH AXIS ARE TRANSPORTING ABUNDANT MID-UPPER LEVEL MOISTURE FROM SOUTH AMERICA ACROSS THE WINDWARD ISLANDS INTO THE TROPICAL N ATLC WHERE SOME SHOWER ACTIVITY IS NOTED. ...HISPANIOLA... THE OUTER RAINBANDS OF HURRICANE JOAQUIN SUPPORT CLOUDINESS ACROSS THE ISLAND WITH POSSIBLE ISOLATED CONVECTION EXPECTED ACROSS THE NORTHERN HALF OF THE ISLAND. SIMILAR ACTIVITY IS EXPECTED TO CONTINUE THROUGH THE NEXT 24 HOURS AS HURRICANE JOAQUIN MOVES SW TOWARD THE BAHAMAS TONIGHT AND THU. ATLANTIC OCEAN... THE MAIN FEATURE OVER THE ATLANTIC IS HURRICANE JOAQUIN...PLEASE SEE SPECIAL FEATURES SECTION ABOVE FOR DETAILS. SWELLS GENERATED BY JOAQUIN WILL AFFECT PORTIONS OF THE BAHAMAS DURING THE NEXT FEW DAYS...AND WILL BEGIN TO AFFECT PORTIONS OF THE SOUTHEASTERN COAST OF THE UNITED STATES BY THURSDAY. THESE SWELLS ARE LIKELY TO CAUSE LIFE-THREATENING SURF AND RIP CURRENT CONDITIONS. TO THE E OF JOAQUIN...A 1009 MB LOW PRES IS NEAR 25.5N 57.5W. PLEASE REFER TO THE SPECIAL FEATURES SECTION FOR MORE DETAILS. A WEAKENING STATIONARY FRONT ENTERS THE FORECAST AREA NEAR 31N21W THEN CONTINUES SW TO NEAR 28N35W TO 24N45W TO 24N50W. SCATTERED MODERATE CONVECTION IS WITHIN 120 NM S OF THE FRONT BETWEEN 27W- 36W. A WEAK PRES GRADIENT IS NOTED ACROSS MUCH OF THE FORECAST REGION...EXCEPT OVER THE NORTH CENTRAL ATLC WHERE FRESH TO STRONG EASTERLY WINDS ARE OBSERVED PER SCATTEROMETER DATA DUE TO THE PRES GRADIENT BETWEEN THE ATLC RIDGE ANCHORED ON A HIGH PRES LOCATED WELL N OF AREA AND THE AFOREMENTIONED LOW PRES. A WEAK SURFACE RIDGE DOMINATES THE MADEIRA/CANARY ISLANDS. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ GR