000 AXNT20 KNHC 200601 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 105 AM EST SUN NOV 20 2011 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0515 UTC. ...SPECIAL FEATURES... AN UPPER LEVEL LOW IS CENTERED NEAR 24N54W WITH AN UPPER LEVEL TROUGH AXIS ORIENTED N-NW TO S-SE ALONG 32N64W TO 13N52W. THIS UPPER LEVEL FEATURE SUPPORTS A COMPLEX AREA OF SURFACE TROUGHING ACROSS THE CENTRAL ATLC WITH A SURFACE TROUGH ANALYZED FROM 12N53W THROUGH A 1011 MB LOW NEAR 21N53W ALONG 27N53W TO BEYOND 32N50W AND WEAKER SURFACE TROUGH ANALYZED FROM 21N57W TO 24N62W. THE DOMINANT EASTERLY SURFACE TROUGH REMAINS THE FOCUS FOR POTENTIAL TROPICAL OR SUB-TROPICAL CYCLONE FORMATION WITH A MEDIUM CHANCE DURING THE NEXT 48 HOURS. ACTIVITY IN THE VICINITY IS ASSOCIATED MORE WITH THE UPPER RIDGE TO THE E RATHER THAN THE LOW/TROUGH ITSELF. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ACROSS AFRICA ENTERING THE E TROPICAL ATLC NEAR 13N17W TO 10N19W. THE ITCZ AXIS EXTENDS FROM 10N19W ALONG 7N27W 7N40W TO NEAR 6N50W. SCATTERED MODERATE/STRONG CONVECTION IS FROM 3N-9N BETWEEN 20W-32W. CLUSTERS OF SCATTERED MODERATE/STRONG CONVECTION ARE FROM 4N-7N BETWEEN 10W-20W. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE FROM 2N-9N BETWEEN 32W-38W. ...DISCUSSION... GULF OF MEXICO... BROAD UPPER RIDGE DOMINATES THE GULF ANCHORED IN THE E PACIFIC REGION WITH THE UPPER RIDGE AXIS EXTENDING ACROSS S MEXICO NEAR VERACRUZ TO OVER NE FLORIDA WITH DRY STABLE AIR ALOFT COVERING THE ENTIRE GULF. A SURFACE RIDGE DOMINATES THE GULF ANCHORED IN THE W ATLC EXTENDING AN AXIS SE CONUS ALONG 30N86W TO TUXPAN MEXICO. RETURN FLOW IS DEVELOPING OVER THE NW GULF TONIGHT. BROKEN LOW CLOUDS WITH SCATTERED SHOWERS ARE OVER THE NE GULF N OF 27N TO OVER THE FLORIDA PANHANDLE BETWEEN 85W-88W LEAVING THE REMAINDER OF THE GULF UNDER CLEAR SKIES TONIGHT. SURFACE RIDGE WILL PERSIST THROUGH MON WITH RETURN FLOW OVER THE NW GULF. A COLD FRONT WILL MOVE OFF THE TEXAS COAST LATE TUE AND EXTEND FROM THE FLORIDA BIG BEND AREA TO VERACRUZ MEXICO BY WED EVENING AND THEN E OF THE GULF THU. CARIBBEAN SEA... THE UPPER RIDGE OVER THE GULF OF MEXICO COVERS THE NW CARIBBEAN N OF 16N W OF 80W. A WEAK INVERTED UPPER TROUGH EXTENDS FROM JAMAICA TO NE NICARAGUA. A SECOND UPPER RIDGE COVERS THE REMAINDER OF THE CARIBBEAN ANCHORED NEAR 15N71W. DRY STABLE AIR ALOFT DOMINATES THE E CARIBBEAN E OF 75W WITH MOIST TROPICAL AIR OVER THE W CARIBBEAN. CLUSTERS OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS DOT THE W CARIBBEAN S OF 20N BETWEEN 73W-83W USHERED IN ON THE STRONG EASTERLY TRADE WINDS. THE MONSOON TROUGH EXTENDS FROM COLOMBIA NEAR 10N75W ALONG 11N80W ACROSS COSTA RICA INTO THE E PACIFIC REGION NEAR 10N85W. ISOLATED LOW LEVEL FAST MOVING SHOWERS ARE POSSIBLE ACROSS THE SE CARIBBEAN S OF 15N E OF 73W ALSO USHERED IN ON THE EASTERLY TRADE WINDS. FRESH TO STRONG NE WINDS WILL PERSIST OVER THE N CARIBBEAN THROUGH EARLY TUE. ATLANTIC OCEAN... A SURFACE RIDGE DOMINATES THE W ATLC EXTENDING INTO THE GULF OF MEXICO ANCHORED BY A 1034 MB HIGH ABOUT 600 NM NE BERMUDA. A SHEAR AXIS IS ANALYZED FROM 30N57W TO JUST E OF THE BAHAMA ISLANDS NEAR 26N76W WITH ISOLATED SHOWERS POSSIBLE WITHIN 75 NM NW OF THE SHEAR AXIS. THE ELONGATED UPPER LEVEL TROUGH/SURFACE FEATURES IN THE SPECIAL FEATURES SECTION ABOVE IS TO THE E OF THE SURFACE RIDGE...SEE ABOVE. A HIGHLY AMPLIFIED UPPER RIDGE IS TO THE E OF THE SPECIAL FEATURES EXTENDING FROM NEAR 12N41W ALONG 23N42W TO BEYOND 32N43W PROVIDING DIFFLUENCE ALOFT TO GENERATE SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS WITHIN 120/150 NM OF LINE FROM 14N47W TO 23N49W AND WITHIN 175 NM OF LINE FROM 22N51W TO BEYOND 32N46W. AN UPPER TROUGH CONTINUES TO DIG S OVER THE E ATLC TO 15N E OF 30W SUPPORTING A COLD FRONT N OF THE DISCUSSION AREA. THE REMAINDER OF THE E ATLC IS DOMINATED BY A SURFACE RIDGE ANCHORED BY A 1026 MB HIGH CENTERED NEAR 34N37W. THE SHEAR LINE WILL MOVE LITTLE AND BECOME DIFFUSE SUN. THE COMPLEX ELONGATED TROUGH WILL REMAIN STATIONARY THROUGH MON BEFORE BEGINNING TO DRIFT NE TUE AND WED. A NEW COLD FRONT WILL ENTER NW PORTIONS WED EVENING AND REACH FROM NEAR 28N65W TO FLORIDA KEYS LATE THU NIGHT. 0 FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ PAW