000 AXNT20 KNHC 292347 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 705 PM EST SAT NOV 29 2008 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 2300 UTC. ...THE ITCZ... THE ITCZ AXIS IS ANALYZED ALONG 6N9W 5N20W 3N30W 4N40W 7N50W AND INTO SOUTH AMERICA NEAR 6N58W. A CLUSTER OF SCATTERED MODERATE/ ISOLATED STRONG CONVECTION IS WITHIN 100NM NORTH OF THE AXIS BETWEEN THE COAST OF AFRICA AND 16W. SCATTERED MODERATE CONVECTION FROM 1N-6N BETWEEN 20W-38W. ...DISCUSSION... GULF OF MEXICO... A STRONG COLD FRONT CONTINUES TO DOMINATE THE WEATHER PATTERN IN THE GULF THIS EVENING. AS OF 2100 UTC...THE FRONT STRETCHED ACROSS SE LOUISIANA ENTERING THE GULF WATERS NEAR 29N91W AND CONTINUING ALONG 27N95W TO THE MEXICO/TEXAS BORDER AND THEN INLAND OVER MEXICO. DOPPLER RADAR MOSAIC AND VISIBLE SATELLITE IMAGERY DEPICT NUMEROUS SHOWERS AND EMBEDDED THUNDERSTORMS BEHIND THE FRONT TO THE GULF COAST IN ADDITION TO WIDESPREAD RAIN ACROSS THE SE CONUS AND OVER THE GULF WATERS NORTH OF 28N. THE FRONTAL BOUNDARY WILL CONTINUE MOVING SE ACROSS THE GULF OVER THE WEEKEND BEFORE EXITING THE REGION MONDAY MORNING. WINDS ARE EXPECTED TO APPROACH GALE FORCE ON EITHER SIDE OF THE FRONT AS IT TRAVERSES THE GULF. THE REMAINDER OF THE GULF IS COVERED BY THE WESTERN PERIPHERY OF A SFC RIDGE CENTERED ON A 1018 MB SFC HIGH IN THE W ATLC. AS SOUTHERLY RETURN FLOW AROUND THIS HIGH DRAWS INCREASED MOISTURE AND INSTABILITY OVER THE GULF REGION...THE THREAT FOR STRONG THUNDERSTORMS WILL EXIST ALONG AND AHEAD OF THE COLD FRONT. LOOKING AHEAD...SFC HIGH PRESSURE WILL BUILD IN THE WAKE OF THE FRONT AND QUICKLY MOVE W-E AHEAD OF THE NEXT COLD FRONT WHICH IS FORECAST TO MOVE OFF THE TEXAS COAST ON WED. CARIBBEAN SEA... A 1010 MB SFC LOW REMAINS SITUATED JUST NORTH OF COSTA RICA NEAR 10N81W. SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ASSOCIATED WITH THIS FEATURE COVER THE SW CARIBBEAN S OF 11N. UPPER LEVEL DIVERGENCE IS SUPPORTING MODERATE CONVECTION FROM 16N-18N WEST OF 74W. PATCHES OF LOW LEVEL MOISTURE EMBEDDED IN THE TRADE WIND FLOW ARE NOTED ACROSS THE REMAINDER OF THE BASIN. A SFC RIDGE CENTERED ON A 1018 MB HIGH IN THE WEST ATLC COVERS THE CARIBBEAN NORTH OF 14N. THIS RIDGE IS EXPECTED TO SHIFT EAST...INCREASING TRADE WIND FLOW THROUGHOUT THE REGION. SOUTHERLY FLOW WILL INCREASE IN THE NW CARIBBEAN IN ADVANCE OF A GULF OF MEXICO COLD FRONT...WHICH IS FORECAST TO REACH THE YUCATAN CHANNEL SUNDAY NIGHT. ATLANTIC OCEAN... A 1018 MB SFC HIGH CENTERED NEAR 28N64W EXTENDS A RIDGE ACROSS THE WEST ATLC MAINTAINING TRANQUIL CONDITIONS. A STATIONARY FRONT NORTH OF THE AREA IS EXPECTED TO GRADUALLY MOVE SOUTH...IMPACTING THE DISCUSSION AREA SUNDAY EVENING. FURTHER EAST...A DEEP-LAYER TROUGH COVERS THE CENTRAL ATLC. AN ASSOCIATED SFC TROUGH EXTENDS FROM 28N45W TO 19N49W. A WEAK SFC LOW HAS DEVELOPED ALONG THE SFC TROUGH NEAR 23N46W. CONVECTION ALONG THE SFC TROUGH HAS BEEN SHEARED TO THE NE WITH SCATTERED SHOWERS NORTH OF 27N BETWEEN 25W-46W. A PERSISTENT SFC TROUGH...REMNANTS OF A COLD FRONT...STRETCHES FROM 20N39W ALONG 14N49W TO 8N60W. SCATTERED MODERATE CONVECTION IS WITHIN 150 NM OF THE TROUGH NE OF 14N53W. A SFC RIDGE AXIS EXTENDS FROM THE AZORES TO THE CANARY ISLANDS AND CONTINUES TO DOMINATE THE E ATLC. ALOFT...A DIFFLUENT PATTERN AROUND AN UPPER RIDGE IS ENHANCING CONVECTION ALONG THE ITCZ. $$ RJW