000 AXNT20 KNHC 202338 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SUN SEP 20 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 IDA IS CENTERED NEAR 18.4N 46.3W AT 20/2100 UTC OR ABOUT 955 NM E OF THE NORTHERN LEEWARD ISLANDS MOVING NW AT 15 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1005 MB. MAXIMUM SUSTAINED WIND SPEED IS 40 KT WITH GUSTS TO 50 KT. SCATTERED MODERATE/STRONG CONVECTION IS WITHIN 120 NM OF THE CENTER OVER THE NE QUADRANT. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 16N-18N BETWEEN 41W-45W. PLEASE SEE THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT5/WTNT25 KNHC FOR MORE DETAILS. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE E TROPICAL ATLC NEAR 16N17W ALONG 10N20W TO 7N35W. SCATTERED MODERATE/ ISOLATED STRONG CONVECTION IS WITHIN 120 NM S OF THE MONSOON TROUGH BETWEEN 24W-26W. SCATTERED MODERATE CONVECTION IS FROM 7N- 10N BETWEEN 45W-50W. ...DISCUSSION... GULF OF MEXICO... AN UPPER RIDGE EXTENDS FROM CENTRAL MEXICO INTO THE GULF NEAR BROWNSVILLE TEXAS ACROSS THE FLORIDA PENINSULA NEAR TAMPA TO NE FLORIDA NEAR JACKSONVILLE AND INTO THE W ATLC. A SHORTWAVE UPPER TROUGH EXTENDS FROM S ALABAMA ACROSS THE W TIP OF THE FLORIDA PENINSULA TO 28N89W IN THE N GULF AND IS PROVIDING ENERGY FOR A WEAKENING COLD FRONT THAT EXTENDS FROM SW GEORGIA ACROSS THE FLORIDA PANHANDLE INTO THE GULF NEAR PENSACOLA THEN W INTO SE LOUISIANA NEAR NEW ORLEANS THEN DISSIPATING ACROSS THE REMAINDER OF LOUISIANA. AN NARROW UPPER TROUGH IN THE W ATLC EXTENDS ACROSS S FLORIDA/FLORIDA KEYS TO NEAR MERIDA MEXICO ON THE YUCATAN PENINSULA SUPPORTING A REMNANT SURFACE TROUGH THAT EXTENDS FROM NEAR 26N83W TO 26N90W. STRONG SUBSIDENCE AND DRY STABLE AIR WITH MOSTLY CLEAR SKIES COVERS THE GULF N OF LINE FROM THE FLORIDA KEYS ALONG 22N87W TO TUXPAN MEXICO. ISOLATED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS ARE S OF THE ABOVE LINE. COLD FRONT WILL CONTINUE WEAKENING THROUGH MON. CARIBBEAN SEA... AN UPPER RIDGE ANCHORED OVER CENTRAL AMERICA COVERS THE FAR NW CARIBBEAN W OF 84W AND IS PROVIDING DIFFLUNCE ALOFT THE GENERATE SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS S OF 21N W OF 84W. AN UPPER LOW IS CENTERED S OF JAMAICA NEAR 15N78W COVERING THE AREA FROM 10N-20N BETWEEN 73W-83W. AFTERNOON SHOWERS/THUNDERSTORMS HAVE DEVELOPED INLAND OVER HISPANIOLA... CUBA...AND JAMAICA. THE ACTIVITY THAT DEVELOPED OVER PUERTO RICO HAS MOVED INTO THE CARIBBEAN WATERS WITHIN 75 NM ALONG THE S COAST. SCATTERED TO NUMEROUS SHOWERS/ISOLATED THUNDERSTORMS THAT HAVE DEVELOPED INLAND OVER COLOMBIA ARE MOVING INTO THE CARIBBEAN WATERS WITHIN 75 NM ALONG THE COAST N OF 9N W OF 72W. THIS IS LEAVING THE REMAINDER OF THE CARIBBEAN WITH CLEAR SKIES THIS EVENING. WEAK SURFACE RIDGE OVER THE SW ATLC WILL SUPPORT GENTLE TO MODERATE TRADE WINDS ACROSS MOST OF THE CARIBBEAN THROUGH TUE EXCEPT FOR MODERATE TO FRESH WINDS IN THE S/CENTRAL CARIBBEAN. ...HISPANIOLA... SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE ACROSS THE ISLAND THIS EVENING. DAYTIME HEATING COUPLED WITH OROGRAPHIC LIFTING WILL CONTINUE TO GENERATE AFTERNOON SHOWERS/THUNDERSTORMS ACROSS THE ISLAND MON AND TUE. ATLANTIC OCEAN... A NARROW UPPER TROUGH EXTENDS THROUGH 32N74W ACROSS S FLORIDA/ FLORIDA KEYS INTO THE S GULF OF MEXICO SUPPORTING A SURFACE TROUGH THAT EXTENDS THROUGH 32N73W TO THE N BAHAMA ISLANDS NEAR 26N79W. AN UPPER RIDGE IS ANCHORED TO THE SE NEAR 22N73W EXTENDING A RIDGE AXIS NE TO BEYOND 32N65W AND IS PROVIDING DIFFLUNCE ALOFT TO GENERATE SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN 90 NM OF LINE FROM OVER CUBA NEAR 23N80W TO 25N76W THEN WITHIN 150 NM OF LINE FROM 26N73W TO 32N67W. A WEAK 1015 MB HIGH IS LOCATED NEAR 26N61W. AN ELONGATED UPPER LOW IS CENTERED NE OF THE LEEWARD ISLANDS NEAR 20N57W WITH THE UPPER TROUGH EXTENDING FROM 10N56W THROUGH THE UPPER LOW TO 29N58W. THE REMNANTS OF T.D. NINE IS A 1009 MB LOW NEAR 19N53W WITH A WEAK SURFACE TROUGH EXTENDING N TO 24N54W. THE UPPER LOW/TROUGH IS GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM 20N- 24N BETWEEN 53W-56W AND SCATTERED SHOWERS WITH POSSIBLE ISOLATED THUNDERSTORMS FROM 16N-20N BETWEEN 53W-58W. AN UPPER RIDGE ANCHORED OVER T.S. IDA EXTENDS N ALONG 25N45W TO BEYOND 32N49W AND IS PROVIDING DIFFLUNCE ALOFT TO GENERATE SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM 22N-31N BETWEEN 44W-53W. A SURFACE RIDGE COVERS THE E ATLC N OF 24N W OF 60W ANCHORED BY A 1030 MB HIGH NW OF THE AZORES. W ATLC SURFACE TROUGH WILL REMAIN NEARLY STATIONARY ACROSS THE AREA THROUGH TUE. A WEAK RIDGE ALONG 23N/25N WILL PERSIST E OF THE BAHAMAS THROUGH MID WEEK. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ PAW