000 AXNT20 KNHC 282346 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT TUE OCT 28 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 2315 UTC. ...TROPICAL WAVES... A TROPICAL WAVE IS ALONG 50W S OF 16N MOVING W 10-15 KT. THE CIMSS VORTICITY PRODUCT SUPPORTS THE WAVE POSITION INDICATED. CONVECTION IS MAINLY WITHIN THE ITCZ. A CLUSTER OF MODERATE TO ISOLATED STRONG CONVECTION COVERS THE AREA FROM 9N-12N BETWEEN 45W-47W. THIS WAVE IS INTERACTING WITH AN UPPER-LEVEL LOW LOCATED AHEAD OF THE WAVE AXIS NEAR 13N53W. A TROPICAL WAVE IS OVER THE LESSER ANTILLES ALONG 61W GENERATING SOME SHOWER ACTIVITY PARTICULARLY BETWEEN GUADELOUPE AND SAINT VINCENT INCLUDING ALSO BARBADOS. ACCORDING TO THE GFS MODEL... THE WAVE WILL SLOWLY MOVE WWD ACROSS THE EASTERN CARIBBEAN TONIGHT AND TOMORROW CROSSING MAINLY SOUTH OF PUERTO RICO AND THE VIRGIN ISLANDS. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 11N14W 8N24W 9N36W 9N45W 10N60W. A SURFACE TROUGH IS EMBEDDED WITHIN THE ITCZ AND RUNS FROM 16N38W TO 6N39W. A 1011 MB SFC LOW IS ALONG THE TROUGH AXIS NEAR 11N. SHOWER ACTIVITY ASSOCIATED WITH THIS LOW REMAINS DISORGANIZED AND UPPER-LEVEL WINDS ARE BECOMING LESS CONDUCIVE. THEREFORE... ANY DEVELOPMENT OF THIS SYSTEM SHOULD BE SLOW TO OCCUR AS IT MOVES SLOWLY WEST-NORTHWESTWARD OVER THE NEXT COUPLE OF DAYS. ELSEWHERE...CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE FROM 7N-11N BETWEEN 21W-28W. SIMILAR CONVECTION IS NEAR 8N33W. ...DISCUSSION... GULF OF MEXICO... A DEEP LAYERED TROUGH EXTENDS FROM THE NE CONUS TO THE NORTHERN BAHAMAS WHILE A RIDGE IS BUILDING ALONG THE MEXICAN COAST/FAR WEST GULF. UNDER THIS PATTERN...STRONG WLY FLOW PREVAILS ACROSS MOST OF THE GULF REGION AND THE STATE OF FLORIDA. THE ASSOCIATED COLD FRONT IS OUT OF AREA OVER THE W ATLC...EASTERN CUBA AND THE NW CARIBBEAN. A SURFACE RIDGE CONTINUES TO BUILD IN BEHIND THE FRONT ANCHORED ON A 1035 MB HIGH LOCATED NEAR THE TEXAS/ OKLAHOMA BORDER. BROKEN TO OVERCAST COLD AIR STRATOCUMULUS CLOUDS COVER THE GULF SOUTH OF 26N. THE COOL AIR IS ALSO BAKING UP AGAINST THE E SLOPE OF THE SIERRA MADRE AND A STATIONARY FRONT IS INDICATED THERE. NLY WINDS OF 20 TO 25 KT ARE BLOWING ACROSS THE GULF. AN UNSEASONABLY COLD NIGHT WITH RECORD LOW LIKELY AT SOME LOCALES IS EXPECTED IN SOUTH FLORIDA UNDER MOSTLY CLEAR SKIES AND DIMINISHING WINDS. CARIBBEAN SEA... A STRONG COLD FRONT OVER THE WEST ATLC AND THE SE BAHAMAS ENTERS THE CARIBBEAN SEA THROUGH EASTERN CUBA THEN CONTINUES SW CROSSING JUST SOUTH OF THE CAYMAN ISLANDS TO THE GULF OF HONDURAS NEAR 16N88W. A REINFORCING COLD FRONT IS OVER CENTRAL CUBA. A 100 NM WIDE BAND OF MULTILAYERED CLOUDS WITH SCATTERED SHOWERS AND TSTMS IS ASSOCIATED WITH THE MAIN FRONT OVER THE CARIBBEAN SEA PARTICULARLY SOUTH OF THE CAYMAN ISLANDS. THE FRONT IS ALSO PRODUCING SOME SHOWER ACTIVITY OVER HONDURAS AND EASTERN CUBA. COLD AIR STRATOCUMULUS CLOUDS NOTICED BEHIND THE COLD FRONT IMPLY THAT A COOL AND DRIER AIR MASS HAS INVADED ALSO THE NW CARIBBEAN AND WESTERN CUBA. A TROPICAL WAVE IS OVER THE LESSER ANTILLES. SEE ABOVE. ALOFT...AN UPPER-LEVEL RIDGE ANCHORED IN THE W ATLC NE OF PUERTO RICO DOMINATES THE AREA GIVING THE CARIBBEAN E OF THE FRONT STRONG SUBSIDENCE AND DRY/ STABLE ATMOSPHERE. A WEAK SFC TROUGH IS BETWEEN THE ISLANDS OF VIEQUES AND CULEBRA AND EASTERN PUERTO RICO. ONLY ISOLATED SHOWERS ARE ASSOCIATED WITH THIS TROUGH. THE STRONG COLD WILL CONTINUE TO MOVE SE AND STALL FROM THE WINDWARD PASSAGE TO THE HONDURAN/NICARAGUAN BORDER LATE WED. N TO NE WIND OF 20-25 KT ARE BLOWING W OF THE FRONT WHILE NE TO E WINDS OF 10-15 KT ARE AHEAD OF THE FRONT. MODERATE TRADE WINDS DOMINATE THE REMAINDER OF THE AREA REACHING 25 KT NEAR THE COLOMBIAN COAST. ATLANTIC OCEAN... THE DEEP LAYERED TROUGH THAT COVERS THE E US EXTENDS OVER THE W ATLC W OF 70W TO THE NORTHERN BAHAMAS PRODUCING STRONG SWLY FLOW. THESE WINDS ARE ADVECTING DEEP TROPICAL MOISTURE FROM THE GULF OF HONDURAS THROUGH CENTRAL CUBA INTO THE W ATLC. THE UPPER TROUGH SUPPORTS A STRONG COLD FRONT WHICH EXTENDS FROM THE BERMUDA ISLAND SW TO EASTERN CUBA AND THE NW CARIBBEAN. A SECONDARY FRONT IS BEHIND AND ENTERS THE AREA NEAR 31N68W THEN CONTINUES SW TO CENTRAL CUBA. THIS FRONT HAS DISSIPATED OVER THE CARIBBEAN SEA AND IS EXPECTED TO MERGE WITH THE MAIN FRONT TONIGHT. MODERATE TO STRONG NWLY WINDS ARE NOTED BEHIND THE SECONDARY FRONT. BROAD UPPER RIDGE COVERS THE REMAINDER OF THE W ATLC AND INTO THE CENTRAL ATLC ANCHORED NE OF PUERTO RICO NEAR 24N62W. UPPER DIFFLUENCE BETWEEN THIS UPPER-LEVEL HIGH AND AN UPPER-LEVEL TROUGH OVER THE CENTRAL ATLC IS HELPING TO INDUCE SOME SHOWER ACTIVITY N OF 22N BETWEEN 48W-54W. AT THE SURFACE...A TROUGH IS ANALYZED IN THIS AREA AND EXTENDS FROM 22N55W ALL THE WAY NE THEN N TO BEYOND 31N47W. A STRONG UPPER-LEVEL RIDGE CENTERED JUST SOUTH OF THE CAPE VERDE ISLANDS COVERS THE DEEP TROPICS EAST OF 45W AND IS ENHANCING CONVECTION ALONG THE ITCZ. $$ GR