000 AXNT20 KNHC 292355 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 705 PM EST THU NOV 29 2007 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... THE ITCZ IS PRETTY ACTIVE THIS EVENING. IT AXIS IS CENTERED ALONG 5N10W 5N25W 5N35W 4N45W 1N50W. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS NOTED FROM 2N-8N BETWEEN 15W-43W. A CLUSTER OF SIMILAR CONVECTION IS ALONG THE COASTLINE OF LIBERIA NEAR 5N9W. DISCUSSION... GULF OF MEXICO... A FEW WEAK SFC FEATURES ARE OVER THE GULF THIS EVENING. ONE IS A COLD FRONT EXTENDING FROM SE LOUISIANA TO THE DEEP SOUTH. THIS FRONT WILL DISSIPATE ON FRI AS HIGH PRES BUILDS IN. A BAND OF MAINLY LOW/MID CLOUDS IS ASSOCIATED WITH THE FRONT. SOME OF THESE CLOUDS ARE BANKING UP AGAINST THE EASTERN SLOPES OF THE SIERRA MADRE MOUNTAINS IN MEXICO...MAINLY N OF TAMPICO. AS OF 2100 UTC...A SFC TROUGH WAS ANALYZED OVER THE NE QUADRANT OF THE GULF AND NORTHERN PORTION OF THE FLORIDA PENINSULA. MOSAIC DOPPLER RADAR FROM THE SE U.S. DEPICTS SCATTERED SHOWERS AND ISOLATED TSTMS OVER NE FLORIDA. A WEAK COASTAL LOW-LEVEL TROUGH IS OVER THE SW SECTOR OF THE GULF GENERATING ISOLATED TO SCATTERED SHOWERS. ALOFT... RIDGING DOMINATES THE PATTERN EXTENDING NW FROM THE CARIBBEAN SEA. ABUNDANT MID/UPPER LEVEL MOISTURE IS FOUND ACROSS THE REGION...PARTICULARLY N OF 24N. LOOKING AHEAD...A STRONG COLD FRONT IS FORECAST TO MOVE OFF THE TEXAS COAST LATE SUN BRINGING AN INCREASE IN WINDS AND SEAS. CARIBBEAN SEA... MAINLY QUIET CONDITIONS PREVAIL ACROSS THE CARIBBEAN SUPPORTED BY WIDESPREAD DRY STABLE AIR. THE DRIEST AIR IS E OF 80W WHERE THE UPPER FLOW BECOMES INCREASINGLY CONFLUENT TO THE SW OF A BROAD CENTRAL ATLC TROUGH. PATCHES OF LOW LEVEL CLOUDS ARE MOVING ACROSS THE NE CARIBBEAN...INCLUDING PUERTO RICO AND THE VIRGIN ISLANDS. THE SAN JUAN DOPPLER RADAR IS SHOWING SCATTERED SHOWERS AND ISOLATED TSTMS OVER THOSE ISLANDS AND ADJACENT COASTAL WATERS. THIS SHOWER ACTIVITY IS AHEAD OF A SFC TROUGH... REFLECTION OF A MID/UPPER-LEVEL LOW LOCATED OVER THE CENTRAL ATLC. THIS FEATURE WILL CONTINUE TO HELP THE SHOWER ACTIVITY OVER THE ATLANTIC WATERS TO MOVE TOWARD THOSE ISLANDS AS IT MOVES WWD. SOME SHOWER ACTIVITY IS ALSO SEEN OVER PANAMA DUE TO THE CLOSE PROXIMITY OF THE EPAC ITCZ...AIDED BY A DIFFLUENT PATTERN ALOFT. FRAGMENTS OF LOW LEVEL MOISTURE ARE ALSO OVER THE CENTRAL CARIBBEAN BETWEEN JAMAICA AND COLOMBIA. TRADE WINDS REMAIN ON THE STRONG SIDE ACROSS THE S PORTION OF THE BASIN. THE STRONGEST WINDS ARE AROUND 25 KT NEAR THE COLOMBIAN COAST AS NOTED IN AN EARLIER QSCAT PASS. WINDS AND SEAS WILL GRADUALLY DECREASE THROUGH FRI AS STRONG HIGH PRES OVER THE W ATLC WEAKENS AND SHIFTS E. IN THE UPPER LEVELS...A RIDGE EXTENDS NW FROM W VENEZUELA/N COLOMBIA TO THE YUCATAN PENINSULA/CHANNEL. ATLANTIC OCEAN... AN ELONGATED MID TO UPPER RIDGE EXTENDS NE FROM THE CARIBBEAN COVERING MUCH OF THE AREA W OF 70W. ABUNDANT SUBSIDENCE IS EMBEDDED IN THE RIDGE PROVIDING FAIR WEATHER ACROSS THE WRN ATLC. IN THE LOWER LEVELS...SFC HIGH PRES EXTENDING SSW FROM THE MID-LATITUDES DOMINATES THE PATTERN. THE TAIL END OF A WEAK COLD FRONT BARELY CLIPS THE AREA ENDING NEAR 31N60W. A SFC TROUGH WAS ANALYZED OVER THE FAR NW PORTION OF THE AREA AND NORTHERN FLORIDA. DOPPLER RADAR SHOWS SCATTERED SHOWERS AND ISOLATED TSTMS RELATED TO THE TROUGH OVER NE FLORIDA. THE MAIN FEATURE IN THE CENTRAL ATLC IS A VERY BROAD MID TO UPPER TROUGH WHICH HAS BEEN NEARLY STATIONARY OVER THE PAST COUPLE OF DAYS. A WELL DEFINED CUT OFF LOW IS EMBEDDED IN THE TROUGH NEAR 25N55W. AN ASSOCIATED WWD MOVING LOW-LEVEL TROUGH IS ALONG 29N49W 23N54W 17N55W. SOME CYCLONIC TURNING IN THE WINDS AND LOWER PRES ARE FOUND NEAR THE TROUGH AXIS. THE COMBINATION OF INSTABILITY ALOFT AND LOW-LEVEL CONVERGENCE IS PRODUCING SCATTERED SHOWERS AND ISOLATED TSTMS MAINLY E OF THE SFC TROUGH FROM 20N-27N BETWEEN 40W-52W. A SFC RIDGE DOMINATES THE E ATLC ANCHORED ON A 1028 MB HIGH LOCATED JUST WEST OF THE AZORES. THIS SYSTEM IS PRODUCING MODERATE TO FRESH TRADE WINDS ACROSS THE REGION. ALOFT...AN UPPER LEVEL TROUGH EXTENDS MAINLY EAST TO WEST ALONG 28N CROSSING THE CANARY ISLANDS. SOUTH OF THE TROUGH...A RIDGE IS IN CONTROL HELPING TO INDUCE THE SHOWER/TSTM ACTIVITY ALONG THE ITCZ AXIS. $$ GR