000 AXNT20 KNHC 202349 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 705 PM EST SAT NOV 20 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 07N12W 04N25W 06N37W 06N45W 06N54W. SCATTERED MODERATE CONVECTION IS WITHIN 120 NM OF THE W AFRICA COAST FROM 05N-08N BETWEEN 10W-13W. WIDELY SCATTERED MODERATE CONVECTION IS FROM 01N-09N BETWEEN 18W-30W. FARTHER WEST...A SURFACE TROUGH IS EMBEDDED WITHIN THE ITCZ EXTENDING FROM 05N42W TO 13N43W. NO SIGNIFICANT CONVECTION IS ASSOCIATED WITH THE SURFACE TROUGH. ...DISCUSSION... GULF OF MEXICO... AN BROAD UPPER LEVEL RIDGE REMAINS ANCHORED IN THE CARIBBEAN SEA AND EXPANDS NORTHWARD OVER THE FLORIDA PENINSULA AND WEST- NORTHWESTWARD OVER MUCH OF MEXICO. WATER VAPOR IMAGERY INDICATES A FAIRLY DRY AND SUBSIDENT AIRMASS RESIDE OVER MUCH OF THE GULF THIS EVENING SUPPORTING OVERALL FAIR CONDITIONS AND MOSTLY CLEAR SKIES. HOWEVER...EMBEDDED WITHIN THE UPPER LEVEL RIDGING...A WEAK UPPER LEVEL SHORTWAVE TROUGH AXIS EXTENDS FROM SE LOUISIANA NEAR 30N89W INTO THE WESTERN GULF NEAR 24N95W. AS A RESULT...A SURFACE TROUGH EXTENDS FROM MOBILE BAY TO 27N90W WITH POSSIBLE ISOLATED SHOWERS OCCURRING WITHIN 45 NM EITHER SIDE OF THE SURFACE TROUGH. ELSEWHERE OVER THE REMAINDER OF THE GULF...A SURFACE RIDGE EXTENDS FROM THE FLORIDA PENINSULA TO THE SW GULF AND EAST-CENTRAL MEXICO NEAR 21N99W PROVIDING FOR E TO SE WINDS UP TO 20 KT. AS SOUTHERLY SURFACE FLOW RE-ESTABLISHES ITSELF OVER THE WESTERN GULF...THE NEXT COLD FRONT IS FORECAST TO EMERGE OFF THE TEXAS COAST LATE THURSDAY. CARIBBEAN SEA... AN UPPER LEVEL ANTICYCLONIC CIRCULATION IS ANCHORED OVER THE EASTERN CARIBBEAN NEAR 15N66W AND EXTENDS AN UPPER LEVEL RIDGE AXIS WESTWARD ALONG 16N TO BEYOND SOUTHERN MEXICO AND INTO THE E PACIFIC. EMBEDDED BENEATH THE UPPER LEVEL RIDGING...A DISSIPATING STATIONARY FRONT IS ANALYZED FROM CENTRAL CUBA NEAR 22N77W OVER THE NW CARIBBEAN TO THE NORTHERN COAST OF HONDURAS NEAR 15N87W. NORTHEASTERLY SURFACE FLOW DOMINATES OVER THE NW CARIBBEAN WITH ISOLATED SHOWERS OCCURRING WITHIN 90 NM EITHER SIDE OF THE FRONT BETWEEN 76W-82W AND WITHIN 210 NM WEST OF THE FRONT W OF 84W...INCLUDING PORTIONS OF THE YUCATAN PENINSULA... BELIZE...AND NORTHERN GUATEMALA. ALSO LOCATED BENEATH THE UPPER LEVEL ANTICYCLONE...A SHEAR LINE EXTENDS ALONG 13N BETWEEN 62W-75W OVER THE SOUTHERN CARIBBEAN. ASIDE FROM WIND SPEED DISCONTINUITIES ACROSS THE SHEAR LINE NOTED ON EARLIER MORNING ASCAT PASSES...MOISTURE CONTINUES TO POOL ALONG THE BOUNDARY WITH WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS OCCURRING FROM 11N-15N BETWEEN 59W-80W. THIS ACTIVITY IS LIKELY ENHANCED DUE TO THE DIFFLUENT ENVIRONMENT ALOFT. AS HIGH PRESSURE CURRENTLY LOCATED OVER THE SW NORTH ATLC STRENGTHENS...NE TO E TRADES ARE FORECAST TO REMAIN STRONG THROUGH TUESDAY. ATLANTIC OCEAN... WITH AN UPPER LEVEL ANTICYCLONE CENTERED OVER THE EASTERN CARIBBEAN SEA...WEST-NORTHWESTERLY UPPER LEVEL FLOW PREVAILS OVER MUCH OF THE WESTERN AND CENTRAL ATLC W OF 40W. WATER VAPOR IMAGERY INDICATES MODERATE TO STRONG SUBSIDENCE RESIDES OVER THIS AREA WHICH CONTINUES TO SUPPORT A 1028 MB HIGH CENTERED IN THE W ATLC NEAR 32N77W. ALONG 40W HOWEVER...BROAD UPPER LEVEL TROUGHING EXISTS NORTH OF THE DISCUSSION AREA AND SUPPORTS A COLD FRONT EXTENDING INTO THE REGION NEAR 32N44W THEN SW TO 22N60W AND WEST TO THE TURKS AND CAICOS ISLANDS NEAR 22N73W. 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. FARTHER EAST...A WEAKNESS WITHIN THE SUBTROPICAL RIDGE IS LOCATED BETWEEN 35W-50W...WITH A SURFACE TROUGH EXTENDING FROM 27N42W TO 22N46W. LOW-LEVEL CONVERGENCE EAST OF THE SURFACE TROUGH IS GENERATING ISOLATED SHOWERS FROM 23N-30N BETWEEN 35W-41W. THE REMAINDER OF THE EASTERN ATLC IS UNDER THE INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1021 MB HIGH CENTERED WEST OF THE MADEIRA ISLANDS NEAR 33N20W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN