000 AXNT20 KNHC 201720 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. ...SPECIAL FEATURES... AS OF 20/1500 UTC...TROPICAL STORM IDA IS CENTERED NEAR 17.3N 44.8W OR ABOUT 970 NM E OF THE LEEWARD ISLANDS MOVING WNW AT 11 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1005 MB. MAXIMUM SUSTAINED WIND SPEED IS 40 KT WITH GUSTS UP TO 50 KT. SCATTERED MODERATE CONVECTION IS FROM 13N TO 19N BETWEEN 38W AND 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 FROM WESTERN AFRICA NEAR 12N16W TO 08N33W. SCATTERED MODERATE CONVECTION IS W OF 18W WITHIN 150 NM OF THE TROUGH AXIS. SOME OF THIS CONVECTION IS ASSOCIATED WITH A TROPICAL WAVE THAT IS ABOUT TO EMERGE OFF THE COAST OF AFRICA. ISOLATED MODERATE CONVECTION IS WITHIN 150 NM S OF THE TROUGH AXIS E OF 21W. ...DISCUSSION... GULF OF MEXICO... A SHARP UPPER TROUGH EXTENDS ALONG THE OFFSHORE WATERS OF THE EASTERN US TO S FL TO THE S CENTRAL GULF NEAR 22N93W...SUPPORTING A SURFACE TROUGH THAT EXTENDS FROM 26N82W TO 25N90W. SCATTERED SHOWERS ARE WITHIN 50 NM OF THE TROUGH AXIS. ANOTHER SURFACE TROUGH OF DIURNAL ORIGINS EXTENDS FROM 22N93W TO 18N94W. NO DEEP CONVECTION IS NOTED WITH THIS TROUGH. A 1006 MB HIGH IS CENTERED NEAR 29N91W. MAINLY GENTLE TO MODERATE SURFACE WINDS COVER THE GULF TODAY. OVER THE NEXT 24 HOURS A COLD FRONT WILL ENTER THE NE GULF. DRY AIR WILL LIMIT CONVECTION ASSOCIATED WITH THIS FRONTAL BOUNDARY. SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS WILL REMAIN POSSIBLE WITH THE E GULF SURFACE TROUGH THROUGH MONDAY. CARIBBEAN SEA... UPPER LEVEL DIFFLUENCE ASSOCIATED WITH UPPER LEVEL RIDGING SUPPORTS ISOLATED MODERATE CONVECTION OVER THE NW CARIBBEAN FROM 15N TO 20N W OF 83W...INCLUDING BELIZE. AN UPPER LOW CENTERED NEAR 15N77W SUPPORTS SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS FROM 13N TO 15N BETWEEN 75W AND 78W. SCATTERED THUNDERSTORMS ARE S OF 10N BETWEEN 78W AND THE COAST OF COLOMBIA ASSOCIATED WITH THE E PACIFIC MONSOON TROUGH. GENTLE TO MODERATE TRADE WINDS ARE OVER THE CARIBBEAN N OF A LINE FROM 20N87W TO 15N61W. MODERATE TO FRESH TRADE WINDS ARE S OF THIS LINE. OVER THE NEXT 24 HOURS CONVECTION WILL CONTINUE OVER THE WESTERN CARIBBEAN. ...HISPANIOLA... LOW LEVEL MOISTURE COMBINED WITH DAYTIME HEATING WILL RESULT IN ISOLATED THUNDERSTORMS OVER THE ISLAND THIS AFTERNOON AND EVENING. GENERALLY FAIR WEATHER IS EXPECTED OVERNIGHT TONIGHT. A SIMILAR PATTERN IS FORECAST FOR MONDAY AND MONDAY NIGHT. ATLANTIC OCEAN... A SHARP UPPER TROUGH ALONG THE EASTERN US COAST SUPPORTS A 1007 MB LOW NEAR 31N75W. A SURFACE TROUGH EXTENDS FROM THIS LOW TO 26N77W TO 23N81W. THE COMBINATION OF ASCENT ASSOCIATED WITH THE UPPER TROUGH AND CONVERGENCE WITH THE SURFACE TROUGH SUPPORTS SCATTERED THUNDERSTORMS WITHIN 300 NM E OF THE TROUGH N OF 26N AND WITHIN 100 NM OF THE TROUGH AXIS S OF 26N. A 1009 MB SURFACE LOW WHICH IS THE REMNANTS OF T.D. NINE IS CENTERED NEAR 19N52W. A SURFACE TROUGH EXTENDS N FROM THE LOW TO NEAR 28N51W. UPPER LEVEL DIFFLUENCE ON THE NE SIDE OF AN UPPER LOW COMBINED WITH THE MOISTURE ASSOCIATED WITH THE SURFACE TROUGH SUPPORTS SCATTERED MODERATE CONVECTION FROM 22N TO 31N BETWEEN 42W AND 54W. TROPICAL STORM IDA IS OVER THE CENTRAL ATLC. PLEASE REFER TO THE SPECIAL FEATURES SECTION FOR MORE DETAILS. FARTHER EAST...A SURFACE TROUGH EXTENDS FROM 27N25W TO 22N23W. NO DEEP CONVECTION IS NOTED. OVER THE NEXT 24 HOURS CONVECTION WILL CONTINUE OVER THE CENTRAL ATLC ASSOCIATED WITH THE REMNANTS OF T.D. NINE...THE SURFACE TROUGH...AND IDA. CONVECTION WILL ALSO CONTINUE BETWEEN BERMUDA AND THE BAHAMAS. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ LATTO