000 AXNT20 KNHC 151749 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 105 PM EST SAT NOV 15 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. ...THE ITCZ... THE ITCZ AXIS IS ANALYZED ALONG 6N10W 5N30W 7N40W 9N50W 10N57W. A SURFACE TROUGH...WHICH EXTENDS FROM 14N57W TO 6N58W...IS EMBEDDED WITHIN THE ITCZ. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS NEAR THE INTERSECTION OF THE TROUGH WITH THE ITCZ COVERING THE AREA FROM 6N-11N BETWEEN 56W-62W. A DIFFLUENT PATTERN ALOFT IS ENHANCING THIS ACTIVITY. ELSEWHERE...SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 4N-10N BETWEEN 21W-33W. SIMILAR CONVECTION IS WITHIN 80 NM SOUTH OF AXIS BETWEEN 13W-20W. ...DISCUSSION... GULF OF MEXICO... A DEEP LAYERED TROUGH OVER THE EAST-CENTRAL CONUS AND THE NORTHERN GULF WATERS SUPPORTS A STRONG COLD FRONT WHICH IS MOVING SE ACROSS THE GULF REGION. AS OF 15/1500 UTC...THE FRONTAL SYSTEM EXTENDS FROM THE FLORIDA BIG BEND ALONG THE CENTRAL GULF NEAR 25N90W INTO NE MEXICO NEAR 23N98W. A PRE- FRONTAL TROUGH LIES WITHIN 100-120 NM SE OF FRONT. A WIDE BAND OF LOW/MID CLOUDS WITH EMBEDDED SHOWERS IS ASSOCIATED WITH THE FRONT/TROUGH. SHOWERS ARE CONCENTRATED NEAR THE LEADING EDGE OF THE BAND. STRONG NLY WIND...ALREADY REACHING GALE FORCE PER A RECENT QSCAT PASS...ARE FOUND BEHIND THE FRONT WHILE SLY WINDS OF 10 TO 15 KT ARE AHEAD OF THE FRONTAL BOUNDARY. A GALE WARNING IS ALREADY IN EFFECT WEST OF THE COLD FRONT WHICH IS EXPECTED TO MOVE RAPIDLY SE AND LIE FROM CEDAR KEY FLORIDA TO THE EASTERN BAY OF CAMPECHE THIS AFTERNOON AND SE OF THE AREA EARLY TONIGHT. THE FRONT IS ALSO FORECAST TO MOVE ACROSS SOUTH FLORIDA EARLY THIS EVENING BRINGING A COOLER AIR MASS WITH TEMPERATURES DROPPING FROM THE UPPER 80S SATURDAY AFTERNOON TO THE LOWER 70S SUNDAY AFTERNOON. AS HIGH PRESSURE RAPIDLY BUILDS IN THE WAKE OF THE FRONT...THE STRONG WINDS SHOULD BEGIN TO SURGE FROM THE NW TO THE SW PORTION OF THE GULF...INCLUDING THE BAY OF CAMPECHE THIS AFTERNOON. DENSE FOG DEVELOPED AHEAD OF THE FRONT OVER SOUTH FLORIDA AND THE YUCATAN PENINSULA THIS MORNING. MERIDA IN THE STATE OF YUCATAN MEXICO REPORTED VISIBILITIES IN THE FOG NEAR ZERO EARLY THIS MORNING. CARIBBEAN SEA... AN UPPER-LEVEL RIDGE ANCHORED ON A HIGH NEAR THE CAYMAN ISLANDS IS AFFECTING THE WESTERN CARIBBEAN...WITH THE UPPER RIDGE AXIS EXTENDING FROM HONDURAS/NICARAGUA THROUGH E-CENTRAL CUBA INTO THE BAHAMAS. SUBSIDENCE IN THE VICINITY OF THIS UPPER RIDGE IS BRINGING MOSTLY FAIR WEATHER TO MUCH OF THE W CARIBBEAN AND CUBA AS WELL AS OVER NORTHERN CENTRAL AMERICA. AN UPPER-LEVEL LOW LOCATED NEAR 15N70W DOMINATES THE REMAINDER OF THE BASIN. SWLY FLOW AHEAD OF THIS LOW IS ENHANCING CONVECTION ASSOCIATED WITH THE TROUGH OVER THE TROPICAL N ATLC ALONG 57W/58W. PART OF THIS ACTIVITY IS AFFECTING THE WINDWARD ISLANDS. TRINIDAD REPORTED 1.16 INCHES OF RAIN THIS MORNING. THE UPPER LOW IS ALSO HELPING TO INDUCE SCATTERED SHOWERS AND ISOLATED TSTMS OVER THE EAST AND CENTRAL CARIBBEAN...INCLUDING PUERTO RICO AND DOMINICAN REPUBLIC. MODERATE TRADE WINDS ARE BLOWING ACROSS THE AREA. THE COLD FRONT CURRENTLY MOVING ACROSS THE GULF OF MEXICO WILL REACH THE YUCATAN CHANNEL AND WESTERN CUBA TONIGHT. INCREASING WINDS IN THE 20 TO 25 KT RANGE WILL FOLLOW THE PASSAGE OF THE FRONT. ATLANTIC OCEAN... AN UPPER-LEVEL RIDGE EXTENDS FROM EAST-CENTRAL CUBA AND THE BAHAMAS BEYOND THE BERMUDAS. SUBSIDENCE RELATED TO THE UPPER FEATURE IS INHIBITING DEEP CONVECTION ACROSS MUCH OF THE W ATLC. FARTHER TO THE E...THE AXIS OF A DEEP LAYERED TROUGH ENTERS THE FORECAST DISCUSSION NEAR 31N42W THEN CONTINUES SW ENTERING THE CARIBBEAN SEA THROUGH THE VIRGIN ISLANDS TO THE ABOVE MENTIONED UPPER-LEVEL LOW. THE ATTENDANT COLD FRONT IS NORTH OF THE AREA BUT A SFC TROUGH EXTENDS FROM THE TAIL END OF THE FRONT NEAR 31N36W ALONG 27N37W TO 23N40W. SCATTERED MODERATE CONVECTION IS WITHIN 200 NM E OF THE TROUGH AND N OF 28N. STRONG WESTERLY FLOW ASSOCIATED WITH A JET STREAM BRANCH WITH CORE WINDS OF 70-90 KT DOMINATES MUCH OF THE TROPICAL ATLC. THE STRONGEST WINDS ARE NOTED JUST N OF THE CAPE VERDE ISLANDS. A WIDE BAND OF TRANSVERSE HIGH CLOUDS IS ASSOCIATED WITH THE JET STREAM AND GOES FROM 14N55W ALL THE WAY E AND THE SE TO THE WEST AFRICAN COAST. AT THE SURFACE...A 1026 MB HIGH CENTERED NEAR 34N57W ENVELOPS THE WEST AND CENTRAL ATLC WITH ANOTHER RIDGE COVERING THE EAST ATLANTIC OCEAN E OF 30W. BETWEEN RIDGES...THE AFOREMENTIONED SFC TROUGH LIES. ANOTHER SFC TROUGH IS ALONG 57W/58W ACCOMPANIED BY A WIND SURGE. MOISTURE FROM THIS TROUGH IS AFFECTING THE WINDWARD ISLANDS. $$ GR