000 AXNT20 KNHC 300603 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0545 UTC. ...SPECIAL FEATURES... TROPICAL STORM JOAQUIN IS CENTERED NEAR 25.8N 71.7W AT 30/0300 UTC OR ABOUT 313 NM E OF THE NORTHWESTERN BAHAMAS MOVING WSW AT 4 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 24N TO 28N BETWEEN 68W AND 73W AND FROM 21N TO 24N BETWEEN 68W AND 75W. JOAQUIN IS EXPECTED TO BECOME A HURRICANE LATER TONIGHT OR WEDNESDAY. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT1/WTNT21 KNHC FOR MORE DETAILS. ...TROPICAL WAVES... A TROPICAL WAVE IS OVER THE E ATLC NEAR THE CAPE VERDE ISLANDS WITH TILTED AXIS EXTENDING FROM 16N19W 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 30W. A TROPICAL WAVE IS IN THE CENTRAL ATLC WITH TILTED AXIS EXTENDING FROM 16N36W SW TO A 1010 MB LOW PRESSURE CENTER EMBEDDED IN THE MONSOON TROUGH NEAR 10N39W...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 08N TO 11N BETWEEN 37W AND 44W. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM A 1009 MB LOW IN THE E ATLC NEAR 11N23W TO 11N34W TO A 1010 MB LOW NEAR 10N39W TO 09N46W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 09N46W TO 06N54W. 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 STRAITS OF FLORIDA. AT THE SURFACE...LOW PRESSURE PREVAILS...EXCEPT IN THE SW BASIN WHERE A WEAK 1011 MB HIGH PRESSURE CENTER IS BEING ANALYZED. A 1010 MB LOW IS IN THE NW GULF NEAR 26N93W WITH ASSOCIATED TROUGH EXTENDING NE TO 29N90W. DRY AIR AND STRONG DEEP LAYER WIND SHEAR INHIBIT CONVECTION NEAR THE LOW. A SECOND LOW OF 1008 MB IS OVER THE BORDER BETWEEN S-SW GEORGIA AND NORTHERN FLORIDA WITH ASSOCIATED TROUGH EXTENDING FROM SOUTHERN MISSISSIPPI TO THE LOW TO SE TO NE FLORIDA OFFSHORE WATERS. FINALLY...A SURFACE TROUGH CONTINUES OVER THE YUCATAN PENINSULA WITH AXIS EXTENDING NE ACROSS THE SE GULF TO 26N84W. BOTH AREAS OF LOW PRESSURE ARE EMBEDDED IN A MODERATE MOIST LOW LEVEL ENVIRONMENT THAT ENHANCES SCATTERED TO ISOLATED SHOWERS E OF 89W. LOOKING AHEAD...A COLD FRONT IS FORECAST TO FORM AND MOVE ACROSS THE WESTERN 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 THAT IS PROVIDING 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 ALONG 10N FROM COSTA RICA TO NORTHERN COLOMBIA. CLOUDINESS AND POSSIBLE 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 AND POSSIBLE ISOLATED SHOWERS ACROSS THE ISLAND. 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 LATER TONIGHT OR WEDNESDAY. SEE SPECIAL FEATURES. AHEAD OF JOAQUIN...A LOW PRESSURE CENTER BETWEEN SOUTHERN GEORGIA AND NORTHERN FLORIDA IS ASSOCIATED WITH A TROUGH THAT EXTENDS SE TO NE FLORIDA OFFSHORE WATERS WHERE IT ENHANCES SCATTERED MODERATE CONVECTION AND TSTMS FROM 27N TO 31N W OF 78W. 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. THE CENTER OF THIS DISTURBANCE IS A 1009 MB LOW NEAR 24N57W FROM WHICH A TROUGH EXTENDS FROM 25N61W TO THE LOW TO 23N55W. SCATTERED MODERATE CONVECTION AND TSTMS ARE FROM 22N TO 26N BETWEEN 51W AND 60W. A BROAD UPPER TROUGH OVER THE CENTRAL N ATLC SUPPORTS A COLD FRONT ALONG 30N25W TO 28N29W WHERE IT TRANSITIONS INTO A STATIONARY FRONT TO A 1014 MB LOW NEAR 25N37W TO 25N50W TO 29N58W. SCATTERED MODERATE CONVECTION IS WITHIN 120 NM EITHER SIDE OF THE FRONTAL BOUNDARY. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ NR