000 AXNT20 KNHC 171136 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 705 AM EST SAT NOV 17 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1115 UTC. ...ITCZ/MONSOON TROUGH... MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE E TROPICAL ATLC NEAR 11N15W ALONG 8N16W TO 6N19W WHERE THE ITCZ AXIS CONTINUES ALONG 4N33W 9N48W TO SOUTH AMERICA NEAR 6N58W. A SURFACE TROUGH IS ALONG THE E SIDE OF AN UPPER TROUGH FROM 20N34W TO 12N40W WITH SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS WITHIN 350 NM E OF THE TROUGH AXIS AND W OF THE TROUGH WITHIN 120 NM OF LINE FROM 17N40W TO 8N45W. A SECOND SURFACE TROUGH IS AT THE BASE OF THE SAME UPPER TROUGH ALONG 48W FROM 10N-16N WITH SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS FROM 10N-12N BETWEEN 45W-48W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 120 NM N AND 60 NM S OF THE ITCZ BETWEEN 20W-23W AND FROM 8N-10N BETWEEN 26W-29W. ...DISCUSSION... GULF OF MEXICO... BROAD UPPER TROUGH EXTENDS FROM THE CANADIAN MARITIMES OVER THE E CONUS INTO THE E GULF OF MEXICO CONTINUING S INTO THE NW CARIBBEAN. A BROAD UPPER RIDGE ANCHORED OVER THE E PACIFIC REGION COVERS THE W GULF. THIS IS GIVING THE GULF MOSTLY NW FLOW ALOFT. A SURFACE RIDGE DOMINATES THE GULF EXTENDING FROM THE GREAT LAKES REGION WITH A 1031 MB HIGH OVER KANSAS. THE UPPER RIDGE IS DRAWING MOIST TROPICAL AIR ACROSS MEXICO INTO THE W GULF AND COUPLED WITH A SURFACE TROUGH THAT IS ALONG THE COAST OF MEXICO FROM 24N97W TO 20N96W ARE GENERATING SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS S OF 24N W OF 93W. DRY STABLE AIR REMAINS OVER THE E GULF N OF 24N BETWEEN 84W-91W. HOWEVER...SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS ARE OVER THE SE GULF S OF 26N E OF 87W GIVING THE REMAINDER OF THE GULF FAIR WEATHER THIS MORNING. SURFACE RIDGE WILL SLOWLY MOVE E AND WEAKEN MON THROUGH WED. A SLIGHTER TIGHTER PRESSURE GRADIENT OVER THE AREA DUE TO THE SURFACE RIDGE AND BROAD TROUGHING OVER THE W ATLC WILL MAINTAIN FRESH NE WINDS OVER THE NE GULF THROUGH MUCH OF SUN. CARIBBEAN SEA... A WEAK PRESSURE PATTERN REMAINS ACROSS THE CARIBBEAN THIS MORNING. THE BROAD UPPER TROUGH OVER THE E GULF OF MEXICO EXTENDS OVER THE NW CARIBBEAN TO CENTRAL AMERICA W OF 77W WHILE AN UPPER RIDGE DOMINATES THE REMAINDER OF THE CARIBBEAN FROM AN UPPER HIGH OVER VENEZUELA WITH THE AXIS EXTENDING ALONG 63W CONTINUING OVER THE W/CENTRAL ATLC. A 1011 MB LOW HAS DEVELOPED IN THE SW CARIBBEAN NEAR 11N81W WITH A SURFACE TROUGH EXTENDING NW TO THE NE COAST OF NICARAGUA. THE MONSOON TROUGH EXTENDS FROM COLOMBIA NEAR 10N75W THROUGH THE ABOVE 1011 MB LOW THEN SW ACROSS COSTA RICA INTO THE E PACIFIC REGION. THESE FEATURES AND DIFFLUENCE ALOFT ON THE W SIDE OF THE UPPER RIDGE ARE GENERATING CLUSTERS OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ACROSS THE CENTRAL CARIBBEAN WITHIN 300 NM OF LINE FROM PANAMA NEAR 9N81W TO ACROSS THE GREATER ANTILLES OVER THE WINDWARD PASSAGE. THIS IS LEAVING THE NW AND E CARIBBEAN WITH FAIR WEATHER THIS MORNING. A WEAK PRESSURE PATTERN WILL MAINTAIN GENERALLY MODERATE TRADE WINDS ACROSS THE AREA THROUGH TUE INCREASING NW CARIBBEAN ON WED. SURFACE LOW IN COMBINATION WITH AN UPPER TROUGH WILL MAINTAIN UNSETTLED WEATHER OVER MUCH OF THE SW AND CENTRAL CARIBBEAN THROUGH SUN. ATLANTIC OCEAN... THE BROAD UPPER TROUGH IN THE GULF OF MEXICO COVERS THE FAR W ATLC W OF 73W SUPPORTING A WEAKENING STATIONARY FRONT THAT EXTENDS THROUGH 32N73W TO THE COAST OF FLORIDA N OF FORT LAUDERDALE. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE N OF THE FRONT TO 32N W OF 75W TO THE COAST OF FLORIDA. THE BROAD UPPER RIDGE OVER THE CARIBBEAN EXTENDS OVER THE W/CENTRAL ATLC ACROSS THE VIRGIN ISLANDS NEAR 18N63W TO BEYOND 32N57W. A SURFACE TROUGH IS BENEATH THE UPPER RIDGE EXTENDING THROUGH 32N62W ALONG 25N66W TO 19N68W. THE SURFACE TROUGH COUPLED WITH THE UPPER RIDGE THAT IS PROVIDING DIFFLUENCE ALOFT ARE GENERATING CLUSTERS OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN 250 NM OF LINE FROM THE GREATER ANTILLES NEAR 20N72W ALONG 25N67W TO 32N62W. AN UPPER TROUGH EXTENDS FROM AN UPPER LOW OVER PORTUGAL ALONG 32N15W CONTINUING TO A SECOND WEAKER UPPER LOW NEAR 23N33W THEN S INTO THE TROPICS TO NEAR 10N49W AND SUPPORTING A COLD FRONT THAT EXTENDS ALONG THE COAST OF AFRICA NEAR 32N9N JUST E OF THE CANARY ISLANDS NEAR 28N13W TO 26N20W. THIS UPPER TROUGH IS ALSO ENHANCING THE ACTIVITY ASSOCIATED WITH THE SURFACE TROUGHS IN THE ITCZ/MONSOON TROUGH SECTION ABOVE. A LARGE SURFACE RIDGE DOMINATES THE ATLC BETWEEN 20W-60W AND IS ANCHORED BY A 1029 MB HIGH ABOUT 300 NM W OF THE AZORES. W ATLC STATIONARY FRONT WILL REMAIN THROUGH TUE WHILE REINFORCING HIGH PRESSURE BUILDS OVER THE SE CONUS. A BROAD AREA OF LOW PRESSURE IS FORECAST TO DEVELOP SUN AND MON OVER THE N CENTRAL ATLC THEN LIFT N OF THE AREA LATE MON INTO TUE. A SURFACE TROUGH EXTENDING S FROM THE LOW WILL LINGER OVER THE CENTRAL ATLC INTO WED AS HIGH PRESSURE CONTINUES ACROSS THE W ATLC. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ PAW