000 AXNT20 KNHC 251739 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT TUE SEP 25 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 1715 UTC. ...SPECIAL FEATURES... TROPICAL STORM NADINE IS CENTERED NEAR 31.9N 30.0W AT 25/1500 UTC OR ABOUT 395 NM SSW OF THE AZORES MOVING WSW AT 5 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 997 MB. MAXIMUM SUSTAINED WIND SPEED IS 40 KT WITH GUSTS TO 50 KT. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS. SCATTERED MODERATE CONVECTION IS WITHIN 30/45 NM OF LINE FROM 32N30W TO 31N32W. ...TROPICAL WAVES... TROPICAL WAVE IN THE E CARIBBEAN EXTENDS FROM 17N64W TO 11N65W MOVING W 10-15 KT. WAVE IS EMBEDDED WITHIN A BROAD AREA OF DEEP MOISTURE AS DEPICTED ON THE TOTAL PRECIPITABLE WATER IMAGERY. WAVE REMAINS TO THE E OF AN UPPER LOW/TROUGH COVERING THE CENTRAL CARIBBEAN. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE E TROPICAL ATLC NEAR 13N16W CONTINUING ALONG 8N24W TO 10N34W. THE ITCZ IS NOT CLEARLY DEFINED IN THE ATLC BASIN. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE FROM 10N-16N BETWEEN 18W-22W. CLUSTERS OF SCATTERED MODERATE CONVECTION ARE FROM 3N-7N BETWEEN 18W-24W...FROM 9N-13N BETWEEN 42W-45W...AND FROM 12N-15N BETWEEN 54W-58W. ...DISCUSSION... GULF OF MEXICO... A BROAD UPPER TROUGH COVERS THE E CONUS INTO THE W ATLC NARROWING AS IT EXTENDS ACROSS NE FLORIDA TO OVER THE E GULF SUPPORTING A STATIONARY FRONT IN THE W ATLC THAT AT 25/1500 UTC DISSIPATES AS IT ENTERS THE GULF OF MEXICO OVER EXTREME S FLORIDA THEN OVER KEY WEST FLORIDA TO 23N88W. SCATTERED SHOWERS/ ISOLATED THUNDERSTORMS ARE WITHIN 120 NM EITHER SIDE OF THE FRONT. AN UPPER RIDGE IS BUILDING OVER THE FAR W GULF ALONG THE COAST OF MEXICO AND TEXAS DRAWING DRY CONTINENTAL AIR OVER THE GULF W OF A LINE FROM 23N90W TO CEDAR KEY FLORIDA. A SURFACE TROUGH IS IN THE SW GULF EXTENDING FROM 23N97W INTO THE BAY OF CAMPECHE TO NEAR 19N93W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 120 NM E OF THE TROUGH S OF 21N. A SURFACE RIDGE ANCHORED IN THE NW ATLC IS BUILDING SW ACROSS THE GULF IN THE WAKE OF THE FRONT CURRENTLY IN THE SE GULF LEAVING THE REMAINDER OF THE GULF WITH CLEAR SKIES THIS AFTERNOON. THE FRONT WILL GRADUALLY DISSIPATE THROUGH EARLY TONIGHT. HIGH PRESSURE BUILDING ACROSS THE GULF WILL REMAIN STRONG THROUGH WED AND GRADUALLY WEAKEN THU THROUGH SAT. CARIBBEAN SEA... AN UPPER RIDGE AXIS EXTENDS FROM AN UPPER HIGH IN THE E PACIFIC REGION ACROSS CENTRAL AMERICA AND THE GULF OF HONDURAS INTO THE W ATLC ACROSS CENTRAL CUBA. THE DISSIPATING STATIONARY FRONT IN THE SE GULF OF MEXICO COUPLED WITH THE UPPER RIDGE IN THE CARIBBEAN IS GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS N OF 21N BETWEEN 83W-87W TO INLAND OVER CUBA AND THROUGH THE YUCATAN CHANNEL. AN UPPER LOW IS IN THE CENTRAL CARIBBEAN CENTERED NEAR 15N72W COVERING THE AREA BETWEEN 64W-81W GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM 11N-18N BETWEEN 63W-73W FURTHER ENHANCED BY THE E CARIBBEAN TROPICAL WAVE. THE MONSOON TROUGH EXTENDS ACROSS THE S CARIBBEAN FROM COLOMBIA TO COSTA RICA INTO THE E PACIFIC REGION ALONG 10N GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS S OF 14N W OF W OF 81W. THIS IS LEAVING THE REMAINDER OF THE CARIBBEAN WITH MOSTLY CLEAR SKIES THIS AFTERNOON. THE TROPICAL WAVE WILL REACH THE CENTRAL CARIBBEAN EARLY WED AND THE W CARIBBEAN EARLY FRI THEN MOVE ACROSS THE REMAINDER OF THE CARIBBEAN LATER FRI AND SAT. ATLANTIC OCEAN... BROAD UPPER TROUGH COVERS THE E CONUS INTO THE NW ATLC EXTENDING ALONG THE EASTERN SEABOARD TO NE FLORIDA SUPPORTING A COLD FRONT N OF THE DISCUSSION AREA AND A STATIONARY FRONT ENTERING THE REGION AT 25/1500 UTC NEAR 32N68W ALONG 28N75W TO OVER S FLORIDA S OF MIAMI DISSIPATING AS IT ENTERS THE GULF OF MEXICO. A BROAD UPPER RIDGE COVERS THE W ATLC ANCHORED NEAR 26N70W EXTENDING A RIDGE AXIS SW ACROSS CENTRAL CUBA INTO THE CARIBBEAN AND NE TO BEYOND 32N65W PROVIDING DIFFLUENCE ALOFT TO GENERATE CLUSTERS OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS NW OF A LINE FROM THE COAST OF CUBA IN THE STRAITS OF FLORIDA NEAR 23N81W ALONG 27N73W TO 31N65W AND E OF A LINE FROM SAINT AUGUSTINE FLORIDA TO 31N78W. AN UPPER LOW IS IN THE CENTRAL ATLC NEAR 24N58W SUPPORTING A SURFACE TROUGH THAT EXTENDS FROM 24N48W TO 19N50W AND GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN 75 NM EITHER SIDE OF THE TROUGH AXIS. A SURFACE RIDGE IS BUILDING SW FROM A 1030 MB HIGH NW OF THE AZORES WITH A RIDGE AXIS EXTENDING THROUGH 32N58W TO NEAR 25N73W. TROPICAL STORM NADINE REMAINS IN THE NE ATLC...SEE SPECIAL FEATURES ABOVE. THE W ATLC STATIONARY FRONT WILL GRADUALLY DISSIPATE BY WED AS HIGH PRESSURE BUILDS S ACROSS THE W ATLC. A WEAK COLD FRONT WILL MOVE ACROSS THE FAR NORTHERN WATERS FRI AND SAT. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ PAW