000 AXNT20 KNHC 301212 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 AM 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1030 UTC. ...SPECIAL FEATURES... TROPICAL STORM JOAQUIN IS CENTERED NEAR 25.4N 72.5W AT 30/0900 UTC OR ABOUT 210 NM ENE OF THE CENTRAL BAHAMAS MOVING WSW AT 5 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 988 MB. MAXIMUM SUSTAINED WIND SPEED IS 60 KT WITH GUSTS TO 75 KT. NUMEROUS MODERATE/ISOLATED STRONG CONVECTION AND ISOLATED TSTMS ARE FROM 22N TO 28N BETWEEN 69W AND 75W AND FROM 19N TO 23N BETWEEN 68W AND 73W. JOAQUIN IS EXPECTED TO BECOME A HURRICANE TODAY. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT1/WTNT21 KNHC FOR MORE DETAILS. A LARGE AREA OF CLOUDINESS CONTINUES OVER THE CENTRAL ATLANTIC ASSOCIATED WITH A 1009 MB SURFACE LOW...REMNANTS OF IDA...CENTERED NEAR 25N58W AND ITS ASSOCIATED FRONTAL TROUGH EXTENDING FROM THE LOW TO 23N52W. THIS SYSTEM HAS BECOME A BETTER ORGANIZED SINCE YESTERDAY AND ADDITIONAL DEVELOPMENT IS EXPECTED DURING THE NEXT SEVERAL DAYS WHILE IT MOVES NW. SCATTERED MODERATE CONVECTION IS OBSERVED FROM 24N-30N BETWEEN 46W-63W. THE CHANCE OF FORMATION OVER THE NEXT 48 HOURS IS MEDIUM. ...TROPICAL WAVES... A TROPICAL WAVE IS OVER THE E ATLC NEAR THE CAPE VERDE ISLANDS WITH TILTED AXIS EXTENDING FROM 16N21W SW TO A 1009 MB LOW PRESSURE CENTER EMBEDDED IN THE MONSOON TROUGH NEAR 11N23W...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 TO ISOLATED MODERATE CONVECTION FROM 06N TO 16N E OF 31W. A TROPICAL WAVE IS IN THE CENTRAL ATLC WITH TILTED AXIS EXTENDING FROM 16N36W SW TO A 1009 MB LOW PRESSURE CENTER EMBEDDED IN THE MONSOON TROUGH NEAR 11N39W...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. SCATTERED MODERATE CONVECTION IS FROM 07N TO 10N BETWEEN 36W AND 44W. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE COAST OF SENEGAL NEAR 14N16W SW TO A 1009 MB LOW NEAR 11N23W TO 11N33W TO A 1009 MB LOW NEAR 11N39W TO 09N47W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 09N47W TO 09N60W. FOR CONVECTION INFORMATION SEE THE TROPICAL WAVES SECTION. ...DISCUSSION... GULF OF MEXICO... SOUTHWESTERLY FLOW CONTINUE TO DOMINATE THE GULF WATERS BETWEEN A MIDDLE TO UPPER LEVEL TROUGH EXTENDING FROM OVER THE MID- MISSISSIPPI RIVER VALLEY SW TO A BASE OVER NE MEXICO AND AN ELONGATED MIDDLE TO UPPER LEVEL RIDGE ANCHORED OVER THE YUCATAN CHANNEL. AT THE SURFACE...LOW PRESSURE PREVAILS...EXCEPT IN THE SW BASIN WHERE A WEAK 1012 MB HIGH PRESSURE CENTER IS BEING ANALYZED. A 1009 MB LOW IS IN THE NW GULF NEAR 26N93W WITH ASSOCIATED TROUGH EXTENDING NE TO 28N90W. DRY AIR AND STRONG DEEP LAYER WIND SHEAR INHIBIT CONVECTION NEAR THE LOW. FINALLY...A SURFACE TROUGH CONTINUES OVER THE YUCATAN PENINSULA WITH AXIS EXTENDING NE ACROSS THE SE GULF TO 23N85W. MODERATE MOIST LOW LEVEL ENVIRONMENT ENHANCES SCATTERED TO ISOLATED SHOWERS AND TSTMS S OF 25N BETWEEN 85W AND 90W. LOOKING AHEAD...A COLD FRONT IS FORECAST TO FORM AND MOVE ACROSS THE GULF LATE THURSDAY INTO FRIDAY INTRODUCING MODERATE TO FRESH NORTH-NORTHEASTERLY WINDS THROUGH SATURDAY. CARIBBEAN SEA... NORTHEASTERLY FLOW PREVAILS OVER MUCH OF THE CENTRAL AND WESTERN CARIBBEAN AND PROVIDES OVERALL STABLE CONDITIONS AND FAIR WEATHER. HOWEVER...ONE EXCEPTION LIES ACROSS THE FAR NW CARIBBEAN WHERE UPPER LEVEL DIFFLUENCE ALONG WITH A LOW LEVEL MOIST ENVIRONMENT SUPPORT ISOLATED SHOWERS W OF 85W. ANOTHER AREA OF ONGOING CONVECTION IS OCCURRING IN THE SW BASIN IN ASSOCIATION WITH CLOSE PROXIMITY OF THE MONSOON TROUGH ANALYZED JUST S OF 10N FROM COSTA RICA TO NORTHERN COLOMBIA OFFSHORE WATERS. CLOUDINESS AND SCATTERED/ISOLATED SHOWERS CONTINUES OVER HISPANIOLA BEING SUPPORTED BY THE OUTER RAIN BANDS OF TROPICAL STORM JOAQUIN IN THE SW N ATLC. OTHERWISE...MOSTLY CLEAR SKIES PREVAIL ELSEWHERE SUPPORTED BY DRY AIR SUBSIDENCE FROM ALOFT AS SHOWN BY WATER VAPOR IMAGERY. MAINLY MODERATE TO FRESH TRADES PERSIST WITH THE STRONGEST WINDS NOTED ACROSS SOUTH-CENTRAL PORTIONS. ...HISPANIOLA... THE OUTER CLOUD/RAIN BANDS OF TROPICAL STORM JOAQUIN IN THE SW N ATLC CONTINUE TO SUPPORT CLOUDINESS ACROSS THE ISLAND WITH POSSIBLE ISOLATED SHOWERS OVER THE W AND CENTRAL HISPANIOLA THIS MORNING. SCATTERED SHOWERS AND ISOLATED TSTMS ARE ALONG THE NORTHERN COAST OF THE ISLAND AND OVER THE EASTERN DOMINICAN REPUBLIC. INTERMITTENT SHOWERS ARE EXPECTED TO CONTINUE THROUGH LATE THURSDAY AS JOAQUIN INTENSIFY INTO A HURRICANE AND MOVES WSW TOWARDS THE BAHAMAS BEFORE TAKING A NORTHWARD TURN FRIDAY. ATLANTIC OCEAN... THE MAIN FEATURE OVER THE ATLC IS TROPICAL STORM JOAQUIN THAT IS EXPECTED TO BECOME A HURRICANE TODAY. SEE SPECIAL FEATURES. AHEAD OF JOAQUIN...REMNANTS OF A FORMER TROUGH ENHANCES SCATTERED MODERATE CONVECTION FROM 27N TO 30N BETWEEN 77W AND 79W. TO THE EAST OF JOAQUIN...A LARGE AREA OF DISTURBED WEATHER IS IN THE CENTRAL ATLC ASSOCIATED WITH A FRONTAL TROUGH AND THE REMNANTS OF IDA. PLEASE SEE THE SPECIAL FEATURES SECTION FOR MORE DETAILS. A BROAD UPPER TROUGH OVER THE CENTRAL N ATLC SUPPORTS A COLD FRONT ALONG 30N24W TO 28N29W WHERE IT TRANSITIONS INTO A STATIONARY FRONT TO 23N40W TO 24N48W. SCATTERED MODERATE CONVECTION IS WITHIN 120 NM N OF THE FRONTAL BOUNDARY. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ NR/ERA