000 AXNT20 KNHC 292351 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT TUE SEP 29 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... TROPICAL STORM JOAQUIN IS CENTERED NEAR 26.0N 71.0W AT 29/2100 UTC OR ABOUT 350 NM E OF THE NORTHWESTERN BAHAMAS MOVING WSW AT 4 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 990 MB. MAXIMUM SUSTAINED WIND SPEED IS 55 KT WITH GUSTS TO 65 KT. NUMEROUS MODERATE AND SCATTERED STRONG CONVECTION IS FROM 23N-27N BETWEEN 68W-72W WITH SCATTERED MODERATE CONVECTION ELSEWHERE FROM 21N- 27N BETWEEN 67W-73W. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT1/WTNT21 KNHC FOR MORE DETAILS. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM 11N22W TO 16N19W MOVING W AT 5 KT. THE WAVE COINCIDES WITH 700 MB TROUGHING ALOFT BETWEEN 18W-23W AS WELL AS A 850 MB RELATIVE VORTICITY MAXIMUM CENTERED ALONG THE WAVE AXIS NEAR 14N21W. IN ADDITION...A SURFACE 1008 MB LOW IS CENTERED AT THE SOUTHERN EXTENT OF THE WAVE AXIS ALONG THE MONSOON TROUGH NEAR 12N19W. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS WITHIN 120 NM EITHER SIDE OF A LINE FROM 09N11W TO 16N18W...WITH ISOLATED MODERATE CONVECTION ELSEWHERE FROM 09N-13N BETWEEN 20W-26W. TROPICAL WAVE EXTENDS FROM 11N39W TO 15N36W MOVING W AT 5-10 KT. THE WAVE COINCIDES WITH A BROAD 700 MB TROUGH AND STRETCHED 850 RELATIVE VORTICITY ALONG THE MONSOON TROUGH AXIS BETWEEN 33W- 41W. LOW-LEVEL STREAMLINE ANALYSIS ALSO INDICATES A 1009 MB LOW CENTERED AT THE SOUTHERN EXTENT OF THE WAVE AXIS AS THE FOCUS OF A BROAD MONSOONAL GYRE. ISOLATED MODERATE CONVECTION IS FROM 09N- 11N BETWEEN 39W-43W. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM 11N21W TO 11N39W TO 09N43W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 09N43W TO 08N51W. NO SIGNIFICANT DEEP CONVECTION IS OCCURRING OUTSIDE OF THE INFLUENCE OF THE TROPICAL WAVES LISTED ABOVE ALONG 20W AND 38W. ...DISCUSSION... GULF OF MEXICO... SOUTHWESTERLY FLOW ALOFT IS NOTED OVER THE GULF THIS EVENING BETWEEN A MIDDLE TO UPPER LEVEL TROUGH AXIS EXTENDING FROM OVER THE MID-MISSISSIPPI RIVER VALLEY SW TO A BASE OVER DEEP SOUTHERN TEXAS AND AN ELONGATED MIDDLE TO UPPER LEVEL RIDGE ANCHORED OVER THE SW NORTH ATLC AND SOUTHERN FLORIDA PENINSULA NEAR 26N80W. AT THE SURFACE...THE TROUGHING SUPPORTS A FAIRLY BROAD AREA OF LOWER PRESSURE VALUES ACROSS THE BASIN FOCUSED ON A 1008 MB LOW CENTERED NEAR 28N94W IN THE NW GULF WATERS...AND A 1008 MB LOW CENTERED ACROSS THE FLORIDA PANHANDLE NEAR 31N85W. MOISTURE IN ALL LEVELS REMAINS PLENTIFUL EAST OF THE TROUGH AXIS WITH ISOLATED SHOWERS AND TSTMS OCCURRING ACROSS THE NORTHWESTERN TWO- THIRDS OF THE GULF...WITH SCATTERED SHOWERS AND TSTMS OCCURRING GENERALLY EAST OF A LINE FROM THE FLORIDA BIG BEND REGION SW TO THE YUCATAN PENINSULA...INCLUDING MUCH OF THE FLORIDA PENINSULA AS WELL. THIS AREA OF ENHANCED CONVECTION CONTINUES WITHIN MAXIMUM MIDDLE TO UPPER LEVEL DIFFLUENCE. 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 THIS EVENING. HOWEVER...ONE EXCEPTION LIES ACROSS THE NW CARIBBEAN WHERE MIDDLE TO UPPER LEVEL DIFFLUENCE IS MAXIMIZED PRODUCING ISOLATED SHOWERS AND TSTMS N OF 19N W OF 84W. ANOTHER AREA OF ONGOING CONVECTION IS OCCURRING ACROSS INLAND PORTIONS OF NORTHERN COLOMBIA...PANAMA...AND COSTA RICA IN ASSOCIATION WITH THE CLOSE PROXIMITY TO THE MONSOON TROUGH ANALYZED ALONG 09N. OTHERWISE...MOSTLY CLEAR SKIES PREVAIL S OF 20N E OF 84W WITH THE EXCEPTION OF A FEW ISOLATED SHOWERS AND TSTMS ACROSS HISPANIOLA. WATER VAPOR IMAGERY INDICATES RELATIVELY STRONG DRY AIR ALOFT IN ASSOCIATION WITH A BROAD AND ELONGATED UPPER LEVEL LOW CENTERED NEAR 18N61W STRETCHING TO ANOTHER UPPER LEVEL LOW NEAR 11N70W. OTHERWISE...MAINLY MODERATE TO FRESH TRADES PERSIST WITH THE STRONGEST WINDS NOTED ACROSS SOUTH-CENTRAL PORTIONS. ...HISPANIOLA... CURRENTLY LINGERING LATE AFTERNOON AND EARLY EVENING ISOLATED SHOWERS CONTINUE TO GRADUALLY DIMINISH WITH MOSTLY FAIR SKIES EXPECTED FOR THE OVERNIGHT HOURS INTO EARLY MONDAY. NE FLOW ALOFT PREVAILS OVER THE ISLAND. ATLANTIC OCEAN... TROPICAL STORM JOAQUIN CONTINUES TO GARNER THE MOST ATTENTION IN THE SW NORTH ATLC WATERS THIS EVENING EXPECTED TO TRACK TOWARD THE CENTRAL AND NW BAHAMAS BY THURSDAY BEFORE ABRUPTLY TURNING NORTH-NORTHEASTWARD DURING THE UPCOMING WEEKEND. AN UPPER LEVEL RIDGE REMAINS ANCHORED TO THE WEST OF THE INFLUENCE OF JOAQUIN ANCHORED NEAR 25N79W PROVIDING AN FAIRLY DIFFLUENT ENVIRONMENT SUPPORTING SCATTERED SHOWERS AND TSTMS THIS EVENING STRETCHING FROM NEAR 32N79W S-SW ACROSS THE WATERS W OF 78W AND PORTIONS OF THE CENTRAL AND SOUTHERN FLORIDA PENINSULA. FARTHER EAST...WATER VAPOR IMAGERY INDICATES A LARGE AND BROAD UPPER LEVEL LOW CENTERED NEAR 39N28W THAT SUPPORTS A COLD FRONT EXTENDING INTO THE DISCUSSION AREA NEAR 32N24W EXTENDING SW TO 28N33W. THE FRONT CONTINUES STATIONARY INTO A WEAK 1013 MB LOW NEAR 26N37W THEN TO 24N43W TO 29N59W. SCATTERED SHOWERS AND ISOLATED TSTMS ARE LARGELY OCCURRING NORTH OF THE FRONT BETWEEN 39W-64W. NEAR THE WESTERN EXTENT OF THE FRONT...A 1009 MB LOW IS ANALYZED TO THE SOUTH NEAR 24N58W. NUMEROUS SHOWERS AND SCATTERED TSTMS ARE OCCURRING WITHIN THE NORTHERN SEMICIRCLE OF THE LOW FROM 23N-27N BETWEEN 53W-62W. MUCH OF THE CONVECTION IS LIKELY ENHANCED DUE TO AN UPPER LEVEL RIDGE AXIS EXTENDING FROM 28N65W TO 24N50W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN