000 AXNT20 KNHC 251727 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 105 PM EST SUN NOV 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1630 UTC. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ACROSS WEST AFRICA TO THE COAST OF SIERRA LEONE AT 7N12W TO 6N17W. THE ITCZ BEGINS AT 6N17W AND CONTINUES ALONG 5N30W 6N44W 5N54W. ISOLATED MODERATE/STRONG CONVECTION IS FROM 5N-7N BETWEEN 11W-16W. ISOLATED MODERATE CONVECTION IS FROM 4N-9N BETWEEN 25W-47W. ...DISCUSSION... GULF OF MEXICO... ZONAL WESTERLY FLOW ALOFT CONTINUES TO COVER THE GULF OF MEXICO TODAY ACCOMPANIED BY A DRY AIRMASS. A BROAD UPPER TROUGH OVER THE NW ATLC SUPPORTS A COLD FRONT THAT EXTENDS THROUGH THE SW NORTH ATLC AND CONTINUES THROUGH THE FLORIDA STRAITS INTO THE SOUTHERN GULF ALONG 25N80W 24N84W 24N91W...AS OF 1500 UTC. A SURFACE TROUGH IS IN THE WESTERN CARIBBEAN ALONG 26N95W TO 19N94W...THE REMNANTS OF THE TAIL END OF THE FRONT WHICH HAS NOW DISSIPATED. DUE TO THE DRY AIRMASS...ONLY A FEW ISOLATED SHOWERS ARE WITHIN 45 NM SOUTH OF THE FRONTAL BOUNDARY AND WITHIN 75 NM EITHER SIDE OF THE SURFACE TROUGH. SURFACE RIDGING AROUND A 1023 MB HIGH CENTERED OVER ALABAMA AND GEORGIA CONTINUES INTO THE NORTHERN GULF BEHIND THE FRONT. THE FRONT WILL CONTINUE EASTWARD INTO THE ATLC ALLOWING SURFACE RIDGING TO DOMINATE UNTIL ANOTHER FRONT MOVES INTO THE GULF ON TUESDAY. CARIBBEAN SEA... MAINLY ZONAL WESTERLY FLOW ALOFT ALSO COVERS THE CARIBBEAN AROUND A BROAD UPPER LEVEL RIDGE WITH A RATHER HORIZONTAL AXIS ALONG 12N. ONLY A SMALL AREA OF MORE SOUTHWESTERLY WINDS COVER THE AREA FROM THE SW CARIBBEAN TO HISPANIOLA WHERE MORE MODERATE MOISTURE IS PRESENT. THIS ALSO IS ATOP AN AREA OF SURFACE CONVERGENCE NEAR A SURFACE TROUGH ALONG 17N73W TO 10N80W. THE CONVERGENCE IS OCCURRING BETWEEN STRONG NORTHERLY WINDS UP TO 20 KT ACROSS THE WESTERN CARIBBEAN AND 15-20 KT EASTERLY TRADEWIND FLOW ACROSS THE EASTERN CARIBBEAN. ISOLATED SHOWERS ARE WITHIN 120 NM OF THE AXIS WITH SCATTERED SHOWERS/THUNDERSTORMS ACROSS THE EXTREME SW CARIBBEAN NORTH OF COSTA RICA AND PANAMA. THIS STRONGER ACTIVITY IS ALSO LIKELY INFLUENCED BY THE MONSOON TROUGH THAT IS JUST SOUTH OF BOTH THE COUNTRIES. AN AREA OF SHOWERS/THUNDERSTORMS IS ALSO IN THE SE CARIBBEAN FROM 11N-14N BETWEEN 63W-71W. THIS ACTIVITY IS ASSOCIATED WITH A SMALL AREA OF ENHANCED MOISTURE THAT TRACKED WESTWARD FROM THE TROPICAL ATLC. THIS AREA OF MOISTURE IS EXPECTED TO CONTINUE MOVING WESTWARD AND WILL THEN MERGE WITH THE SURFACE TROUGH IN THE CENTRAL CARIBBEAN LIKELY INCREASING SHOWER/THUNDERSTORM ACTIVITY. ATLANTIC OCEAN... A BROAD UPPER LEVEL TROUGH COVERS THE NW ATLC SUPPORTING A COLD FRONT THAT ENTERS THE DISCUSSION AREA NEAR 32N61W AND CONTINUES TOWARDS THE NW BAHAMAS ALONG 27N73W 25N80W. DUE TO MOSTLY DRY AIR ALOFT...ONLY A FEW POSSIBLE ISOLATED SHOWERS ARE ALONG THE AXIS. THE SYSTEM ALSO SUPPORTS A SECOND COLD FRONT FARTHER EAST ENTERING THE AREA NEAR 32N45W AND CONTINUES ALONG 27N48W 24N55W WHERE IT CONTINUES AS A SURFACE TROUGH TO 19N64W. SIMILAR TO THE WESTWARD FRONT....ONLY POSSIBLE ISOLATED SHOWERS ARE ALONG THE FRONT/TROUGH AXIS. AN UPPER LEVEL RIDGE COVERS THE CENTRAL ATLC WITH AXIS EXTENDING FROM THE SOUTHERN CARIBBEAN AND CONTINUING NE UNTIL IT BECOMES VERTICAL ALONG 34W. THE UPPER RIDGE SUPPORTS A SURFACE RIDGE ACROSS THE MAJORITY OF THE EASTERN TROPICAL ATLC ANCHORED BY A 1030 MB AZORES HIGH. HOWEVER...A DEEP LAYERED LOW WITH SURFACE CENTER NEAR THE MADEIRA ISLANDS SUPPORTS A COLD FRONT THAT CROSS THE CANARY ISLANDS AND EXTENDS TO 22N28W. THE TIGHT GRADIENT NEAR THE SURFACE LOW IS PRODUCING GALE FORCE WINDS NEAR 30N BEHIND THE FRONT WITH STORM FORCE WINDS FARTHER NORTH. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ WALTON