000 AXNT20 KNHC 221804 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT TUE SEP 22 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1745 UTC. ...SPECIAL FEATURES... THE CENTER OF TROPICAL STORM IDA AT 22/1500 UTC IS NEAR 20.5N 47.5W. IDA IS MOVING TOWARD THE EAST-SOUTHEAST...OR 120 DEGREES AT 7 KNOTS. THE MINIMUM CENTRAL PRESSURE IS 1005 MB. THE MAXIMUM SUSTAINED WIND SPEED IS 40 KNOTS WITH GUSTS TO 50 KNOTS. PUBLIC ADVISORIES ABOUT TROPICAL STORM IDA ARE BEING ISSUED UNDER THE WMO HEADER WTNT35 KNHC...AND UNDER THE AWIPS HEADER MIATCPAT5. FORECAST/ADVISORIES ABOUT TROPICAL STORM IDA ARE BEING ISSUED UNDER THE WMO HEADER WTNT25 KNHC...AND UNDER THE AWIPS HEADER MIATCMAT5. CONVECTIVE PRECIPITATION...SE OF THE CENTER...NUMEROUS STRONG FROM 18N TO 20N BETWEEN 45W AND 47W. NUMEROUS MODERATE FROM 16N TO 21N BETWEEN 41W AND 48W. SCATTERED MODERATE FROM 21N TO 26N BETWEEN 33W AND 44W. ...TROPICAL WAVES... A TROPICAL WAVE IS OVER THE E ATLC WATERS WITH AXIS E OF THE CAPE VERDE ISLANDS NEAR 22W...MOVING W AT 5-10 KT WITHIN THE LAST 24 HOURS. CIRA LAYER PRECIPITABLE WATER IMAGERY SHOW THE WAVE IS MAINLY EMBEDDED IN A MODERATE MOIST ENVIRONMENT FROM THE SURFACE TO 850 MB. HOWEVER...THE IMAGERY ALSO SHOW DRY AIR IN THE WAVE ENVIRONMENT WHICH IS LIMITING THE CONVECTION TO ISOLATED MODERATE FROM 09N TO 18N E OF 27W. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM WESTERN AFRICA NEAR 12N16W TO 07N24W TO 07N35W. THE ITCZ EXTENDS FROM 07N35W TO 07N41W TO 08N48W. ASIDE FROM THE CONVECTION ASSOCIATED WITH THE TROPICAL WAVE...SCATTERED MODERATE CONVECTION IS S OF THE MONSOON TROUGH FROM 04N TO 10N E OF 23W. ...DISCUSSION... GULF OF MEXICO... A BROAD AREA OF LOW PRESSURE EXTENDS FROM THE NW ATLC SW TO AN INVEST AREA OF 1008 MB NEAR 34N73W FROM WHICH A COLD FRONT EXTENDS SW TO JACKSONVILLE FLORIDA. FROM THERE...THE FRONT TRANSITIONS TO A STATIONARY FRONT THAT EXTENDS OVER THE NE GULF OF MEXICO FROM 30N84W TO SE LOUISIANA NEAR 29N90W. THIS FRONTAL SYSTEM IS BEING SUPPORTED BY A MIDDLE TO UPPER LEVEL TROUGH ALONG THE E CONUS WITH BASE EXTENDING TO THE NORTHERN YUCATAN PENINSULA. THE TROUGH ALOFT ALSO SUPPORTS A 1013 MB LOW CENTERED NEAR 26N87W WITH ASSOCIATED SURFACE TROUGH EXTENDING FROM 28N85W TO THE LOW CENTER TO 24N92W. SHALLOW MOISTURE BEING ADVECTED FROM THE CARIBBEAN SEA ALONG WITH A DIFFLUENT ENVIRONMENT ALOFT SUPPORT SCATTERED SHOWERS AND TSTMS EAST OF 87W. SIMILAR CONVECTION IS OBSERVED IN THE BAY OF CAMPECHE S OF 19N...REMNANTS OF A FORMER SURFACE TROUGH. STRONG DEEP LAYER WIND SHEAR AND DRY AIR SUPPORT FAIR WEATHER ELSEWHERE. E-NE WIND FLOW OF 15 KT IS OVER THE N-NE BASIN...LIGHTER VARIABLE WINDS ARE OVER THE REMAINDER GULF. LOW PRESSURE WILL DOMINATE ACROSS THE BASIN THE NEXT TWO DAYS. SURFACE RIDGING WILL START TO BUILD ACROSS THE GULF FRIDAY. CARIBBEAN SEA... SHALLOW MOISTURE ACROSS THE NW CARIBBEAN ALONG WITH A TROUGH ALOFT SUPPORT SCATTERED SHOWERS AND TSTMS N OF 15N W OF 80W. ABUNDANT MOISTURE OVER THE SW BASIN AND A DIVERGENT WIND ENVIRONMENT ALOFT SUPPORT HEAVY SHOWERS AND TSTMS FROM 10N TO 15N W OF 78W. SIMILAR ATMOSPHERIC CONDITIONS OVER THE N-CENTRAL CARIBBEAN SUPPORT ISOLATED SHOWERS IN THE WINDWARD PASSAGE AND HAITI SOUTHERN ADJACENT WATERS. A BROAD UPPER LEVEL LOW IS OVER THE ATLC NE OF PUERTO RICO EXTENDING A TROUGH S ACROSS THE EASTERN CARIBBEAN TO NORTHERN VENEZUELA...ENHANCING SHOWERS AND TSTMS ACROSS PUERTO RICO AND COASTAL WATERS. DRY AIR AND STRONG DEEP LAYER WIND SHEAR INHIBIT CONVECTIVE ACTIVITY OVER THE REMAINDER S-SE CARIBBEAN. TRADES OF 15 KT DOMINATE OVER THE CENTRAL BASIN...LIGHTER WINDS ARE ELSEWHERE. NO SIGNIFICANT CHANGES ARE EXPECTED THE NEXT THREE DAYS. ...HISPANIOLA... MAINLY CLEAR SKIES ARE ACROSS THE ISLAND BEING INFLUENCED BY DRY AIR SUBSIDENCE FROM RIDGING ALOFT AND STRONG DEEP LAYER WIND SHEAR. TO THE W-SW OF THE ISLAND...SHALLOW MOISTURE AND A DIFFLUENT ENVIRONMENT ALOFT SUPPORT SCATTERED SHOWERS IN THE WINDWARD PASSAGE AND HAITI SOUTHERN ADJACENT WATERS. AFTERNOON/EVENING SHOWERS ARE EXPECTED TO DEVELOP THE NEXT THREE DAYS AS A MOIST AIRMASS MOVES ACROSS THE ISLAND. ATLANTIC OCEAN... THE MAIN FEATURE IN THE BASIN IS TROPICAL STORM IDA ALREADY DISCUSSED IN THE SPECIAL FEATURES SECTION ABOVE. W-NW OF IDA...AN UPPER LEVEL LOW SUPPORT SCATTERED SHOWERS AND TSTMS FROM 20N TO 26N BETWEEN 58W AND 67W. OVER THE SW N ATLC...A MIDDLE TO UPPER LEVEL TROUGH ALONG THE E CONUS WITH BASE EXTENDING TO THE NORTHERN YUCATAN PENINSULA SUPPORTS A FRONTAL SYSTEM ANALYZED AS A COLD FRONT FROM AN INVEST AREA ANCHORED BY A 1008 MB LOW NEAR 34N73W SW TO A 1013 MB LOW NEAR 31N77W TO THE COAST OF JACKSONVILLE WHERE IT TRANSITIONS TO A STATIONARY FRONT INTO THE NE GULF OF MEXICO. A SURFACE TROUGH IS ANALYZED AHEAD OF THE FRONT FROM 30N75W TO 27N78W. NO CONVECTION IS OBSERVED AT THIS TIME. DIFFLUENCE ALOFT BEING GENERATED BY A SHORT-WAVE TROUGH OVER THE NW CARIBBEAN AND RIDGING EXTENDING ACROSS THE CENTRAL BAHAMAS SUPPORT SCATTERED SHOWERS AND TSTMS S OF 25N W OF 74W. THE REMAINDER BASIN IS BEING INFLUENCED BY A SURFACE RIDGE CENTERED BY A 1029 MB HIGH NEAR 43N31W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ NR