000 AXNT20 KNHC 242341 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT MON SEP 24 2012 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 NADINE IS CENTERED NEAR 31.7N 28.6W AT 24/2100 UTC OR ABOUT 385 NM SSW OF THE AZORES MOVING W AT 6 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 993 MB. MAXIMUM SUSTAINED WIND SPEED IS 45 KT WITH GUSTS TO 55 KT. WIDELY SCATTERED MODERATE CONVECTION IS FROM 31N-36N BETWEEN 26W-32W. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM 12N59W TO 19N56W MOVING W AT 15 KT. THE WAVE REMAINS ON THE WESTERN PERIPHERY OF VERY BROAD LOW- LEVEL TROUGHING ACROSS THE TROPICAL ATLC S OF 20N BETWEEN 45W-60W. TOTAL PRECIPITABLE WATER IMAGERY INDICATES ELEVATED VALUES EAST OF THE LESSER ANTILLES FROM 10N-18N BETWEEN 53W-60W...WHICH STRETCH WESTWARD INTO THE SOUTHEASTERN CARIBBEAN SEA S OF 15N E OF 69W. WHILE NO SIGNIFICANT DEEP CONVECTION IS IN THE VICINITY OF THE AXIS OF THE WAVE...SCATTERED MODERATE CONVECTION IS OCCURRING ACROSS THE EASTERN CARIBBEAN FROM 10N-17N BETWEEN 61W-68W. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 15N17W TO 09N31W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 09N31W TO 10N44W. WIDELY SCATTERED MODERATE CONVECTION IS FROM 09N-15N BETWEEN 13W-18W. ISOLATED MODERATE CONVECTION IS FROM 06N-15N BETWEEN 22W-38W. ...DISCUSSION... GULF OF MEXICO... WATER VAPOR IMAGERY INDICATES AN UPPER LEVEL SHORTWAVE TROUGH IS OVER THE WESTERN GULF WITH AXIS EXTENDING FROM 30N89W TO A BASE NEAR 22N96W. EAST OF THIS UPPER LEVEL TROUGH AXIS...UPPER LEVEL DIFFLUENCE IS MAXIMIZED OVER MUCH OF THE CENTRAL AND EASTERN GULF...INCLUDING THE FLORIDA PENINSULA DUE TO MOIST SOUTHWESTERLY FLOW BETWEEN THE TROUGHING AND AN UPPER LEVEL RIDGE AXIS EXTENDING FROM OVER CENTRAL AMERICA NEAR 17N90W EAST- NORTHEASTWARD TO BEYOND 30N64W. THE UPPER LEVEL SHORTWAVE TROUGH IS A PORTION OF A LARGER LONGWAVE TROUGH LOCATED OVER THE EASTERN CONUS THAT SUPPORTS A COLD FRONT ANALYZED ACROSS THE SW NORTH ATLC TO THE SOUTHERN FLORIDA PENINSULA AND WESTWARD INTO THE GULF OF MEXICO AS A STATIONARY FRONT FROM 26N82W TO 24N90W. ONLY ISOLATED SHOWERS AND TSTMS ARE ASSOCIATED WITH THE FRONT S OF 25N BETWEEN 84W-97W. MUCH OF THE MOISTURE NORTH OF THE FRONTAL BOUNDARY REMAINS AS BROKEN TO OVERCAST MIDDLE TO HIGH LEVEL CLOUDINESS. A SURFACE TROUGH IS ALSO ANALYZED ACROSS THE SW GULF FROM 23N95W TO 17N93W AND IS ALSO LIKELY A FOCUS FOR THE SCATTERED SHOWERS AND TSTMS OCCURRING OVER THE SW GULF S OF 23N W OF 90W. THE FRONT IS FORECAST TO BECOME MORE AND MORE DIFFUSE OVER THE NEXT 24 TO 36 HOURS AS SURFACE HIGH PRESSURE REMAINS OVER THE NORTHERN GULF WATERS AND COASTAL PLAINS THROUGH LATE TUESDAY. MOSTLY EASTERLY FLOW IS EXPECTED TO PERSIST ON THE SOUTHERN PERIPHERY OF THE HIGH IN THE RANGE OF 10 TO 20 KT. AS THE HIGH SHIFTS EASTWARD BY EARLY WEDNESDAY...E TO SE WINDS ARE FORECAST TO RE-ESTABLISH ACROSS THE WESTERN GULF. CARIBBEAN SEA... AN UPPER LEVEL RIDGE AXIS EXTENDS FROM OVER PORTIONS OF CENTRAL AMERICA NEAR 17N90W EAST-NORTHEASTWARD TO BEYOND 30N64W. WITH A STATIONARY FRONT DRAPED ACROSS THE SE GULF OF MEXICO AND DIFFLUENCE MAXIMIZED IN ASSOCIATION WITH THE UPPER LEVEL RIDGING...SCATTERED SHOWERS AND TSTMS ARE OCCURRING OVER MUCH OF THE NW CARIBBEAN NW OF A LINE FROM THE WINDWARD PASSAGE NEAR 20N74W TO 12N84W. THE MOST INTENSE ACTIVITY THIS EVENING IS LOCATED OVER CUBA...THE YUCATAN CHANNEL...AND PORTIONS OF THE YUCATAN PENINSULA...INCLUDING NORTHERN GUATEMALA. FARTHER SE... THE MONSOON TROUGH AXIS EXTENDS INTO THE SW CARIBBEAN ALONG 10N AND IS PROVIDING FOCUS FOR SCATTERED SHOWERS AND ISOLATED TSTMS S OF 12N BETWEEN 76W-85W...INCLUDING PORTIONS OF PANAMA...COSTA RICA...AND SOUTHERN NICARAGUA. THE CENTRAL CARIBBEAN REMAINS UNDER MOSTLY FAIR CONDITIONS AND CLEAR SKIES BETWEEN 70W-76W. AN UPPER LEVEL LOW CENTERED OVER PUERTO RICO NEAR 18N66W EXTENDS TROUGHING TO ANOTHER UPPER LEVEL LOW NEAR 13N74W AND NE FLOW ALOFT IS LIKELY PROVIDING A SUBSIDENT ENVIRONMENT FOR THE CENTRAL CARIBBEAN. FINALLY...EAST OF THE UPPER LEVEL TROUGHING...MOIST SOUTHWESTERLY FLOW DOMINATES EAST OF A PUERTO RICO TO ARUBA LINE WITH SCATTERED SHOWERS AND TSTMS OCCURRING EAST OF THAT LINE...INCLUDING PUERTO RICO AND THE LESSER ANTILLES THIS EVENING. THE APPROACH OF A TROPICAL WAVE ALONG 58W WILL LIKELY CONTINUE TO ENHANCE THIS CONVECTIVE ACTIVITY THROUGH THE OVERNIGHT HOURS INTO TUESDAY. ATLANTIC OCEAN... AN UPPER LEVEL TROUGH HAS EMERGED OFF THE EASTERN SEABOARD OF THE CONUS AND SUPPORTS A COLD FRONT ANALYZED INTO THE DISCUSSION AREA ALONG 32N70W TO 27N76W TO THE SOUTHERN FLORIDA PENINSULA NEAR 26N80W. LOW-LEVEL CONVERGENCE ALONG THE FRONT IN CONCERT WITH MIDDLE TO UPPER LEVEL DIFFLUENCE EAST OF THE TROUGH AXIS IS GENERATING SCATTERED SHOWERS AND ISOLATED TSTMS OVER MUCH OF THE SW NORTH ATLC WEST OF A LINE FROM BERMUDA NEAR 32N65W TO 24N69W TO 22N77W. THE COLD FRONT IS FORECAST TO CONTINUE LIFTING NORTH- NORTHEASTWARD OVER THE NEXT 24 TO 36 HOURS WITH A STATIONARY FRONT FORECAST TO LINGER ACROSS THE NW BAHAMAS AND SOUTHERN FLORIDA PENINSULA THROUGH TUESDAY AS THE UPPER LEVEL SUPPORT LIFTS NORTHWARD. FARTHER EAST...THE CENTRAL ATLC IS UNDER THE INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1030 MB HIGH CENTERED NEAR 42N41W. THE SURFACE RIDGE AXIS EXTENDS SOUTHWEST FROM THE HIGH TO 26N65W. THE ONLY AREA OF ACTIVE WEATHER WITHIN REACH OF THE SURFACE RIDGE IS AN UPPER LEVEL LOW CENTERED NEAR 27N59W WHICH IS GENERATING WIDELY SCATTERED SHOWERS FROM 25N-32N BETWEEN 55W-59W. THE REMAINDER OF THE EASTERN ATLC IS UNDER THE INFLUENCE OF TROPICAL STORM NADINE N OF 27N BETWEEN 22W-35W... AND A 1016 MB HIGH CENTERED SOUTH OF NADINE NEAR 20N31W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN