000 AXNT20 KNHC 191805 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT SAT SEP 19 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... TROPICAL STORM IDA IS CENTERED NEAR 14.8N 39.7W AT 19/1500 UTC OR ABOUT 910 NM W OF THE CAPE VERDE ISLANDS MOVING WNW AT 10 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1006 MB. MAXIMUM SUSTAINED WIND SPEED IS 35 KT WITH GUSTS TO 45 KT. SCATTERED MODERATE CONVECTION IS FROM 08N-18N BETWEEN 34W-41W. PLEASE SEE THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT5/WTNT25 KNHC FOR MORE DETAILS. TROPICAL DEPRESSION NINE IS CENTERED NEAR 18.4N 49.8W AT 19/1500 UTC OR ABOUT 683 NM ENE OF THE LESSER ANTILLES MOVING WNW AT 5 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1007 MB. MAXIMUM SUSTAINED WIND SPEED IS 25 KT WITH GUSTS UP TO 35 KT. ISOLATED SHOWERS ARE POSSIBLE WITHIN 120 NM OF THE DEPRESSION CENTER. A WEAKENING TREND IS FORECAST TO CONTINUE...AND THE DEPRESSION IS EXPECTED TO DISSIPATE WITHIN THE NEXT 24-48 HOURS. PLEASE SEE THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM WESTERN AFRICA NEAR 09N13W TO 07N21W TO 08N30W. THE ITCZ REMAINS INDISCERNIBLE. SCATTERED MODERATE CONVECTION IS WITHIN 120 NM EITHER SIDE OF THE MONSOON TROUGH BETWEEN 17W-26W. ...DISCUSSION... GULF OF MEXICO... A SURFACE RIDGE CONTINUES TO BUILD ACROSS THE N-NW GULF UNDER THE INFLUENCE OF A BROAD ANTICYCLONE ALOFT CENTERED OVER NORTHERN MEXICO. CIRA LAYERED AND SSMI TOTAL PRECIPITABLE WATER IMAGERY AS WELL AS WATER VAPOR IMAGERY DEPICT VERY DRY AIR OVER THIS REGION...EXTENDING OVER THE E AND S BASIN ALOFT. A NARROW MIDDLE TO UPPER LEVEL TROUGH EXTENDS FROM THE SE CONUS SW INTO THE E GULF WITH BASE REACHING THE OFFSHORE WATERS OF THE YUCATAN PENINSULA. THE TROUGH ALOFT SUPPORTS A NEWLY FORMED 1011 MB LOW PRESSURE CENTER NEAR 27N85W THAT ALONG WITH SHALLOW MOISTURE SUPPORT ISOLATED SHOWERS AND TSTMS FROM 26N TO 28N E OF 89W. SIMILAR SHOWER ACTIVITY IS OBSERVED OVER THE SE BASIN ASSOCIATED WITH THE TAIL OF A SURFACE TROUGH EXTENDING ACROSS THE FLORIDA STRAITS TO 22N85W. THE SURFACE TROUGH WILL MOVE OFF THE BASIN INTO SW N ATLC WATERS BY SUNDAY MORNING. A COLD FRONT IS EXPECTED TO STALL OVER THE SE CONUS WITH TAIL REACHING THE FLORIDA PANHANDLE TO LOUISIANA COASTAL WATERS MONDAY...DISSIPATING OVER N-NE GULF OF MEXICO TUESDAY MORNING. CARIBBEAN SEA... THE PASSAGE OF A TROPICAL WAVE ACROSS CENTRAL AMERICA THIS MORNING LEFT A TROUGH OF LOW PRESSURE OVER THE NW CARIBBEAN WITH AXIS EXTENDING FROM 21N86W TO 16N88W...WHICH ALONG WITH LOW TO MIDDLE LEVEL MOISTURE SUPPORT SCATTERED SHOWERS AND TSTMS WITHIN 260 NM OFF THE YUCATAN PENINSULA E COAST. THE MONSOON TROUGH MOVES FROM EPAC WATERS ACROSS PANAMA TO NORTHERN COLOMBIA AND ALONG A REGION OF MIDDLE TO UPPER LEVEL DIFFLUENCE SUPPORT HEAVY SHOWERS AND TSTMS SW OF A LINE FROM 15N83W TO 11N74W AND S OF 13N BETWEEN 70W AND 73W. SHALLOW MOISTURE IS OVER THE NE AND SE CARIBBEAN ENHANCING ISOLATED SHOWERS OVER PUERTO RICO AND THE WINDWARD ISLANDS. FAIR WEATHER PREVAILS ACROSS THE REMAINDER BASIN. TRADES OF 10 TO 15 KT DOMINATE BASIN WIDE. LITTLE CHANGE IS EXPECTED OVER THE NEXT 24-48 HOURS. ...HISPANIOLA... CLOUDINESS HAS INCREASED ACROSS THE ISLAND...ESPECIALLY DOMINICAN REPUBLIC BEING SUPPORTED BY SHALLOW MOISTURE MOVING OVER THE REGION AS SEEN IN SSMI TPW IMAGERY. HOWEVER...DRY AIR SUBSIDENCE FROM ALOFT FAVORS FAIR WEATHER. EXPECT SCATTERED SHOWERS AND THUNDERSTORMS TO DEVELOP OVER THE HIGHER ELEVATIONS OF HISPANIOLA IN THE AFTERNOON. THIS ACTIVITY WILL DISSIPATE IN THE EVENING HOURS. EXPECT A SIMILAR WEATHER PATTERN OVER THE NEXT 24 HOURS. ATLANTIC OCEAN... THE MAIN FEATURES IN THE BASIN ARE T.S. IDA AND TROPICAL DEPRESSION NINE. FOR MORE DETAILS...PLEASE SEE THE SPECIAL FEATURES SECTION ABOVE. A NARROW MIDDLE TO UPPER LEVEL TROUGH EXTENDS FROM THE SE CONUS SW INTO THE E GULF WITH BASE REACHING THE OFFSHORE WATERS OF THE YUCATAN PENINSULA. THIS TROUGH ALSO EXTENDING OFFSHORE THE SE CONUS CONTINUES TO SUPPORT A 1007 MB LOW N OF THE AREA WITH ASSOCIATED SURFACE TROUGH EXTENDING FROM 30N77W TO NORTHERN BAHAMAS NEAR 26N77W TO COASTAL WATERS OF WESTERN CUBA. SCATTERED SHOWERS AND TSTMS ARE N OF 25N BETWEEN 67W AND 79W. THE REMAINDER BASIN IS BEING INFLUENCED BY A SURFACE RIDGE CENTERED BY A 1025 MB HIGH NEAR 35N43W. SCATTERED MODERATE CONVECTION IS OVER THE CENTRAL BASIN N OF 20N BETWEEN 40W AND 53W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ NR