000 AXNT20 KNHC 011032 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT THU OCT 01 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1030 UTC. ...SPECIAL FEATURES... MAJOR HURRICANE JOAQUIN WILL BATTER THE CENTRAL BAHAMAS WITH HURRICANE FORCE WINDS...STORM SURGE...AND HEAVY RAIN THROUGH TONIGHT. THE CENTER OF JOAQUIN AT 0900 UTC IS LOCATED NEAR 23.4N 73.7W OR ABOUT 19 NM N OF SAMANA CAYS BAHAMAS AND MOVES WSW AT 4 KT. THE CENTER OF JOAQUIN IS EXPECTED TO MOVE NEAR OR OVER PORTIONS OF THE CENTRAL BAHAMAS OVERNIGHT AND THU. MAXIMUM SUSTAINED WIND SPEED IS 105 KT WITH GUSTS TO 130 KT. NUMEROUS STRONG CONVECTION IS FROM 21N TO 25N BETWEEN 71W AND 75W. NUMEROUS MODERATE CONVECTION IS ELSEWHERE FROM 18N TO 26N BETWEEN 69W AND 77W. THE OUTER RAINBANDS OF JOAQUIN ARE ALSO AFFECTING EASTERN CUBA...THE WINDWARD PASSAGE AND HISPANIOLA WHERE SCATTERED MODERATE CONVECTION AND TSTMS ARE NOTED IN SATELLITE IMAGERY. JOAQUIN IS EXPECTED TO PRODUCE 10-15 INCHES OF RAIN OVER MUCH OF THE CENTRAL BAHAMAS AND 5-10 INCHES OVER THE SOUTHEASTERN BAHAMAS THROUGH FRI NIGHT. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT1/WTNT21 KNHC FOR MORE DETAILS. A 1008 MB LOW PRES IS ANALYZED NEAR 25N56W ALONG WITH AN OLD FRONTAL TROUGH THAT EXTENDS FROM 27N65W TO THE LOW CENTER TO 24N48W. SCATTERED TO ISOLATED MODERATE CONVECTION AND TSTMS ARE FROM 20N TO 29N BETWEEN 50W AND 64W. CLOUDINESS AND TSTMS ASSOCIATED WITH THIS SYSTEM HAVE BECOME A LITTLE BETTER ORGANIZED. ENVIRONMENTAL CONDITIONS ARE EXPECTED TO BE CONDUCIVE FOR A TROPICAL DEPRESSION TO FORM BY THE WEEKEND WHILE THE LOW MOVES SLOWLY NW TO N. 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 OVER THE E ATLC MOVING ACROSS THE CAPE VERDE ISLANDS WITH AXIS NEAR 24W...MOVING W AT 5 KT. CIRA LAYER PRECIPITABLE WATER IMAGERY SHOW THE WAVE IS EMBEDDED IN A MODERATE MOIST ENVIRONMENT FROM THE SURFACE TO 850 MB THAT ALONG WITH MIDDLE TO UPPER LEVEL DIFFLUENCE IN THE WAVE REGION SUPPORT SCATTERED MODERATE CONVECTION FROM 06N TO 18N BETWEEN 19W AND 28W. A TROPICAL WAVE IS IN THE CENTRAL ATLC WITH AXIS NEAR 42W CONNECTED TO A 1009 MB LOW OBSERVED IN ASCAT DATA NEAR 11N42W ...MOVING W AT 5-10 KT. CIRA LAYER PRECIPITABLE WATER IMAGERY SHOW THE WAVE IS EMBEDDED IN A MODERATE MOIST ENVIRONMENT FROM THE SURFACE TO 850 MB. HOWEVER...SOME DRY AIR INTRUSION IS ALSO DEPICTED IN THE N-NW WAVE ENVIRONMENT...WHERE METEOSAT ENHANCED IMAGERY SHOW DRY AIR AND DUST. STRONG DEEP LAYER WIND SHEAR INFLUENCES LACK OF CONVECTION. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE COAST OF AFRICA NEAR 13N16W TO 12N23W...THEN RESUMES W OF A TROPICAL WAVE NEAR 11N25W TO 13N37W TO 10N52W. THE ITCZ WAS NOT DISCERNIBLE. FOR CONVECTION INFORMATION SEE THE TROPICAL WAVES SECTION. ...DISCUSSION... GULF OF MEXICO... A SHARP MIDDLE- TO UPPER-LEVEL TROUGH EXTENDS FROM ILLINOIS TO LOUISIANA SW TO A BASE OVER THE SW GULF OF MEXICO. 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. THE TROUGH ALOFT SUPPORTS A FRONTAL SYSTEM ANALYZED AS A COLD FRONT FROM THE FLORIDA PANHANDLE NEAR 30N84W TO 28N90W TO 28N96W. IT ALSO SUPPORTS A 1009 MB LOW PRES LOCATED NEAR 23N91W WITH A TROUGH EXTENDING FROM 26N88W TO THE LOW TO 22N94W. EXCEPT FOR THE SE GULF AND THE YUCATAN CHANNEL...THE CIRA LPW IMAGERY SHOW LOW LEVEL DRY AIR ACROSS THE BASIN THAT ALONG WITH STRONG DEEP LAYER ENVIRONMENTAL WIND SHEAR HINDER CONVECTION. LOOKING AHEAD...THE COLD FRONT IS FORECAST TO REACH THE SE GULF AND START TO DISSIPATE LATE THU. 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 CENTRAL 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 TODAY...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 20-30 KT. THE OUTER RAINBANDS OF JOAQUIN REACH EASTERN CUBA...THE WINDWARD PASSAGE AND GREAT PORTIONS OF HISPANIOLA WHERE SCATTERED MODERATE CONVECTION AND TSTMS ARE OBSERVED. IN THE SW BASIN...THE MONSOON TROUGH GENERATES SOME SHOWER AND TSTMS ACTIVITY OVER PARTS OF PANAMA AND COSTA RICA AND ADJACENT WATERS. 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 E 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 EXTEND ACROSS THE ISLAND WHERE SCATTERED SHOWERS AND TSTMS ARE OBSERVED. SIMILAR ACTIVITY IS EXPECTED TO CONTINUE THROUGH THE NEXT 24 HOURS AS HURRICANE JOAQUIN MOVES SW TOWARD THE BAHAMAS TODAY. 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 1008 MB LOW PRES IS NEAR 25N56W ALONG WITH AN OLD FRONTAL TROUGH THAT EXTENDS FROM 27N65W TO THE LOW CENTER TO 24N48W. 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. PLEASE REFER TO THE SPECIAL FEATURES SECTION FOR MORE DETAILS. A WEAKENING STATIONARY FRONT ENTERS THE FORECAST AREA NEAR 30N22W THEN CONTINUES SW TO NEAR 28N30W TO 27N40W TO 29N46W. SCATTERED MODERATE CONVECTION IS N OF 26N BETWEEN 16W AND 50W. A WEAK SURFACE RIDGE DOMINATES THE MADEIRA/CANARY ISLANDS. 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