000 AXNT20 KNHC 212347 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 705 PM EST SUN NOV 21 2010 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...METEOROLOGICAL ANALYSIS...WEATHER OBSERVATIONS...AND RADAR. BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...ITCZ... ITCZ AXIS IS ANALYZED ALONG 06N10W 04N18W 04N27W 04N36W 07N45W 06N53W. SCATTERED MODERATE CONVECTION IS FROM 02N-07N BETWEEN 06W-13W. WIDELY SCATTERED MODERATE CONVECTION IS FROM THE EQUATOR TO 08N BETWEEN 17W-24W. A SURFACE TROUGH IS EMBEDDED WITHIN THE ITCZ FROM 03N-10N ALONG 27W WITH ISOLATED MODERATE CONVECTION WITHIN 90 NM EITHER SIDE OF THE TROUGH AXIS. FARTHER WEST...ANOTHER SURFACE TROUGH EXTENDS FROM 05N-13N ALONG 49W WITH ISOLATED MODERATE CONVECTION FROM 07N-11N BETWEEN 42W-50W. ...DISCUSSION... GULF OF MEXICO... A SHORTWAVE UPPER LEVEL TROUGH AXIS IS EMBEDDED WITHIN DRY AIR ALOFT AND EXTENDS FROM THE SOUTHERN FLORIDA PENINSULA INTO THE SE GULF NEAR 24N88W. HOWEVER...DUE TO SUCH STRONG SUBSIDENCE... THE UPPER LEVEL TROUGH IS NOT SUPPORTING ANY SIGNIFICANT WEATHER BESIDES A FEW SHOWERS OCCURRING OVER THE SOUTHERN FLORIDA PENINSULA S OF 27N. ELSEWHERE...SURFACE RIDGING DOMINATES THE BASIN ANCHORED BY A 1029 MB HIGH CENTERED IN THE SW NORTH ATLC OFF THE COAST OF THE CAROLINAS NEAR 33N73W. FURTHERMORE...AN UPPER LEVEL RIDGE AXIS EXTENDS FROM THE SW GULF N-NE OVER THE SE CONUS THAT CONTINUES TO SUPPORT THE EXPANSIVE SURFACE RIDGE. AS THE SURFACE HIGH OVER THE W ATLC REMAINS NEARLY STATIONARY AND GRADUALLY WEAKENS THROUGH TUESDAY...A FRONTAL BOUNDARY WILL APPROACH THE TEXAS GULF COAST AND EMERGE INTO THE NW WATERS LATE THURSDAY. CARIBBEAN SEA... AN UPPER LEVEL ANTICYCLONIC CIRCULATION IS ANCHORED OVER THE SE CARIBBEAN NEAR 13N63W AND EXTENDS AN UPPER LEVEL RIDGE AXIS WESTWARD TO BEYOND NORTHERN GUATEMALA NEAR 17N90W. EMBEDDED BENEATH THE UPPER LEVEL RIDGING...A SURFACE TROUGH IS ANALYZED FROM 10N-15N ALONG 83W GENERATING SCATTERED SHOWERS AND ISOLATED TSTMS OVER THE SW CARIBBEAN WATERS SW OF A LINE FROM 15N83W TO 11N77W...INCLUDING INLAND PORTIONS OF WESTERN PANAMA...COSTA RICA...AND MUCH OF NICARAGUA. UPPER LEVEL DIFFLUENCE CONTINUES TO BE MAXIMIZED OVER THIS AREA AS SOUTHEASTERLY FLOW ALOFT FANS OUT OVER THE NW CARIBBEAN. ELSEWHERE...LOW-LEVEL SURFACE CONVERGENCE AND DIFFERENTIAL HEATING ALONG COASTAL REGIONS OF NORTHERN SOUTH AMERICA CONTINUE TO PRODUCE SCATTERED SHOWERS AND ISOLATED TSTMS WITHIN 120 NM EITHER SIDE OF A LINE FROM 09N62W TO 13N76W. THE REMAINDER OF THE CARIBBEAN IS UNDER THE INFLUENCE OF STRONG NE TRADES ON THE SOUTHERN PERIPHERY OF A WESTERN ATLC HIGH PRESSURE...THAT CONTINUES TO FEED ISOLATED SHOWERS OVER THE GREATER ANTILLES AND LEEWARD ISLANDS THIS EVENING. THE NE TO E TRADES ARE FORECAST TO REMAIN STRONG THROUGH LATE WEDNESDAY. ATLANTIC OCEAN... WITH AN UPPER LEVEL ANTICYCLONE CENTERED OVER THE SE CARIBBEAN SEA...WESTERLY ZONAL UPPER LEVEL FLOW PREVAILS OVER MUCH OF THE BASIN BETWEEN 15N AND 32N. WATER VAPOR IMAGERY INDICATES MODERATE TO STRONG SUBSIDENCE RESIDES OVER THIS AREA THAT CONTINUES TO SUPPORT A 1029 MB HIGH CENTERED IN THE W ATLC NEAR 33N73W. BETWEEN 28W-36W NORTH OF THE DISCUSSION AREA...BROAD UPPER LEVEL TROUGHING EXISTS AND SUPPORTS A COLD FRONT EXTENDING INTO THE REGION NEAR 32N33W THEN SW TO 20N56W. WHILE UPPER LEVEL DYNAMICS CONTINUE TO SUPPRESS DEEP CONVECTION ALONG THE FRONT...LOW-LEVEL MOISTURE AND POSSIBLE ISOLATED SHOWERS ARE FOUND WITHIN 90 NM EITHER SIDE OF THE FRONT. A PRE-FRONTAL SURFACE TROUGH IS ANALYZED FROM 23N43W TO BEYOND 32N30W WITH LOW-LEVEL CONVERGENCE MAXIMIZED EAST OF THE SURFACE TROUGH GENERATING ISOLATED SHOWERS FROM 24N-32N BETWEEN 27W-35W. THE REMAINDER OF THE EASTERN ATLC IS UNDER THE INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1018 MB HIGH CENTERED WEST OF THE MADEIRA ISLANDS NEAR 32N19W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN