000 AXNT20 KNHC 112344 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT TUE MAR 11 2008 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN SECTIONS OF SOUTH AMERICA...AND THE 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. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 7N12W 3N20W CROSSING THE EQUATOR NEAR 24W THEN ALONG 3S30W TO 3S40W. CLUSTERS OF SCATTERED MODERATE/STRONG CONVECTION ARE FROM EQUATOR TO THE COAST OF SW AFRICA BETWEEN THE PRIME MERIDIAN AND 14W. SIMILAR CONVECTION IS SEEN OVER NE BRAZIL. ...DISCUSSION... GULF OF MEXICO... A WEAK SHORTWAVE TROUGH OVER THE LOWER MISSISSIPPI VALLEY SUPPORTS A COLD FRONT THAT IS MOVING EWD ACROSS THE CENTRAL GULF. AT 2100 UTC...THE FRONT EXTENDS FROM A 1013 MB LOW LOCATED NEAR 28N87W THROUGH THE CENTRAL GULF INTO THE BAY OF CAMPECHE. THE COLD FRONT SHOULD ONLY MAKE SLOW SEWD PROGRESS TONIGHT AND EARLY WED...UNTIL A SECOND SOUTHERN STREAM SHORTWAVE MOVING THROUGH THE SOUTHERN PLAINS REACHES THE GULF COAST EARLY WED AND DRIVES THE FRONT THROUGH THE REMAINDER OF THE GULF AND SOUTH FLORIDA LATE WED. HIGH PRES CURRENTLY OVER TEXAS WILL BUILD IN GIVING THE AREA LIGHT TO MODERATE NLY FLOW. MEANWHILE...A DISSIPATING FRONTAL BOUNDARY REMAINS NEARLY STATIONARY ACROSS SOUTH FLORIDA AND THE KEYS GENERATING SOME CLOUDINESS. DOPPLER RADAR SHOWS SCATTERED SHOWERS AND TSTMS OVER THE STRAITS OF FLORIDA JUST SOUTH OF THE FLORIDA KEYS AS WELL AS SOME SHOWER ACTIVITY OVER THE NE CORNER OF THE GULF AND THE FLORIDA PANHANDLE ASSOCIATED WITH THE ABOVE MENTIONED SFC LOW. ADDITIONAL SHOWERS AND ISOLATED TSTMS ARE DEVELOPING OVER THE YUCATAN PENINSULA AND REGIONAL WATERS ASSOCIATED WITH A SFC TROUGH THAT RUNS FROM 24N87W TO 19N89W. ALOFT...NEARLY WLY UPPER LEVEL WINDS DOMINATES THE ENTIRE GULF. A JET STREAM BRANCH WITH CORE WINDS OF 90-110 KT EXTENDS ACROSS THE N GULF WATERS AND N FLORIDA INTO THE W ATLC. CARIBBEAN SEA... A MID TO UPPER-LEVEL RIDGE ANCHORED ON A HIGH LOCATED JUST SOUTH OF JAMAICA AT UPPER LEVELS CONTINUES TO DOMINATE THE WEATHER PATTERN ACROSS THE CARIBBEAN SEA AND CENTRAL AMERICA...WITH AN AXIS ALONG 15N-16N. AN UPPER TROUGH FROM THE CENTRAL ATLC EXTENDS INTO THE FAR SE CARIBBEAN AND CENTRAL VENEZUELA. STRONG SUBSIDENCE IS ASSOCIATED WITH THESE UPPER FEATURES. AS USUAL... PATCHES OF LOW LEVEL MOISTURE EMBEDDED IN THE TRADE WIND FLOW ARE MOVING ACROSS THE AREA PRODUCING ISOLATED TO SCATTERED PASSING SHOWERS PARTICULARLY OVER JAMAICA AND COASTAL WATERS. SIMILAR CLOUDINESS IS OBSERVED OVER CENTRAL AMERICA BETWEEN WEST PANAMA AND NE HONDURAS. WEAK ATLC HIGH PRES WILL MAINTAIN MAINLY LIGHT TO MODERATE TRADES THROUGH FRI. THE GULF FRONT DESCRIBED ABOVE SHOULD REACH THE YUCATAN CHANNEL EARLY WED. ATLANTIC OCEAN... A DEEP LAYERED TROUGH IS OVER THE WESTERN ATLC WITH THE ATTENDANT COLD FRONT ENTERING THE FORECAST AREA NEAR 32N50W THEN CONTINUES SW TO NEAR 28N60W. AT THIS POINT...THE FRONT BECOMES STATIONARY CROSSING AS A DIFFUSE FRONTAL BOUNDARY THE NW BAHAMAS AND SOUTH FLORIDA. A BROKEN BAND OF LOW/MID CLOUDS IS RELATED TO THE FRONT MAINLY EAST OF 70W. A WEAK 1022 MB HIGH IS BEHIND THE FRONT...WEST OF BERMUDAS NEAR 32N68W. THIS HIGH WILL MOVE EWD AS A COLD FRONT ENTERS THE W ATLC WED MORNING. FARTHER EAST...A WEAK SFC TROUGH...REFLECTION OF AN UPPER TROUGH OVER THE CENTRAL ATLC EXTENDS FROM 32N44W TO 23N48W. LITTLE OR NO SHOWER ACTIVITY IS ASSOCIATED WITH THE TROUGH DUE TO THE DRY AND STABLE ENVIRONMENT OVER THE AREA. A 1026 MB HIGH CENTERED E OF THE AZORES EXTENDS A RIDGE ACROSS THE E ATLC. THE COMBINATION OF THIS HIGH AND LOWER PRES OVER AFRICA IS PRODUCING A SWATH OF NE WINDS UP TO 25 KT BETWEEN THE CANARY/CAPE VERDE ISLANDS AND THE WEST COAST OF AFRICA. ELSEWHERE...MID TO UPPER LEVEL HIGH PRESSURE OVER THE CARIBBEAN THIS EVENING SHOULD BUILD EWD INTO THE TROPICAL ATLC MIDDLE AND LATE WEEK...REPLACING THE CURRENT SHORTWAVE TROUGH LYING FROM 27N37W TO 11N62W. A BROAD RIDGE REMAINS OVER THE EASTERN ATLC WITH A HIGH LOCATED SW OF THE CAPE VERDE ISLANDS. STRONG SWLY UPPER FLOW BETWEEN THESE UPPER FEATURES IS ADVECTING ABUNDANT UPPER LEVEL MOISTURE FROM N SOUTH AMERICA ALL THE WAY NE BEYOND 30N25W. $$ GR