000 AXNT20 KNHC 272359 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT MON OCT 27 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 ABOUT MIDWAY BETWEEN THE CAPE VERDE ISLANDS AND THE LESSER ANTILLES ALONG 43W S OF 16N MOVING W 10-15 KT. A LARGE AREA OF SHOWERS AND TSTMS IS ASSOCIATED WITH THIS WAVE. ALTHOUGH THIS SYSTEM IS SHOWING SOME SIGNS OF ORGANIZATION...ANY FURTHER DEVELOPMENT SHOULD BE SLOW TO OCCUR AS THE SYSTEM CONTINUES TO MOVE SLOWLY WESTWARD OVER THE NEXT COUPLE OF DAYS. SCATTERED MODERATE CONVECTION IS WITHIN 200 NM E OF WAVE AXIS FROM 8N-14N. STRONG UPPER DIFFLUENCE IS ENHANCING CONVECTION IN THIS AREA. A TROPICAL WAVE IS ALONG 56W/57W S OF 15N MOVING W 10-15 KT. A DIFFLUENT PATTERN ALOFT BETWEEN AN UPPER-LEVEL HIGH OVER THE CARIBBEAN SEA AND AN UPPER-LEVEL TROUGH OVER THE N TROPICAL ATLC IS HELPING TO INDUCE SOME SHOWER ACTIVITY NEAR THE NORTHERN END OF THE WAVE AXIS. ...THE ITCZ... ITCZ AXIS IS ANALYZED ALONG 10N15W 8N30W 9N41W 7N50W 7N61W. SCATTERED MODERATE CONVECTION IS FROM 3N-11N BETWEEN 22W-34W... AND FROM 9N-14N BETWEEN 35W-40W. ...DISCUSSION... GULF OF MEXICO... AN UNUSUALLY STRONG 1040 MB SURFACE HIGH IS CENTERED OVER NORTHERN TEXAS. AT THE LEADING EDGE OF THIS CONTINENTAL POLAR AIRMASS IS A STRONG COLD FRONT THAT EXTENDS ACROSS NORTH FLORIDA AND THE NORTHERN GULF WATERS. A ROPE CLOUD DELINEATES THE FRONTAL BOUNDARY WHICH IS RAPIDLY MOVING ACROSS THE GULF REGION AS SEEN ON VIS SATELLITE PICTURES. THE FRONT IS EXPECTED TO CLEAR THE ENTIRE GULF BY EARLY TUE MORNING WITH TEMPERATURES DROPPING TO NEAR THE RECORDS ACROSS SOUTH FLORIDA TUESDAY NIGHT/ WEDNESDAY MORNING. AN EARLIER ASCAT PASS SHOWED INCREASING NLY WINDS OF 20 TO 30 KT BEHIND THE FRONT...AND NLY WINDS OF 15 TO 20 KT AHEAD OF THE FRONTAL SYSTEM. A DEEP LAYERED TROUGH OVER THE E CONUS SUPPORTS THE AFOREMENTIONED COLD FRONT...WITH STRONG MID/UPPER-LEVEL WESTERLY WINDS OVER THE N GULF. AS HIGH PRES BUILDS IN...A VERY TIGHT PRES GRADIENT HAS DEVELOPED ALONG AND INLAND THE MEXICAN COAST. AS A RESULT...STRONG NLY WINDS ARE BLOWING THROUGH THE ISTHMUS OF TEHUANTEPEC PRODUCING A GAP WIND EVENT IN THE E PACIFIC REGION. THESE WINDS ARE ALREADY REACHING GALE FORCE...AND ARE EXPECTED TO INCREASE TO STORM FORCE BY 1800 UTC TUESDAY. CARIBBEAN SEA... A NEARLY STATIONARY FRONTAL BOUNDARY STRETCHES ACROSS THE GULF OF HONDURAS AND WESTERN CUBA...THEN CONTINUES AS A COLD FRONT OVER THE BAHAMAS AND THE W ATLC TO A 1010 MB LOW LOCATED NEAR 39N67W. A 120 NM WIDE BAND OF MULTILAYERED CLOUDS WITH SCATTERED SHOWERS AND ISOLATED TSTMS IS RELATED TO THE FRONT ACROSS THE CARIBBEAN SEA WITH THE STRONGEST SHOWER ACTIVITY OVER CENTRAL CUBA. THE DEEP LAYERED TROUGH OVER THE EASTERN U.S. ALSO SUPPORTS THIS FRONT. AN UPPER-LEVEL HIGH CENTERED BETWEEN HISPANIOLA AND THE SE BAHAMAS EXTENDS A RIDGE OVER MOST OF THE BASIN. SWLY FLOW N OF THIS UPPER RIDGE CONTINUES TO TRANSPORT DEEP TROPICAL MOISTURE INTO THE NW CARIBBEAN WHICH IS INTERACTING WITH THE ABOVE MENTIONED STATIONARY FRONT. AN UPPER-LEVEL TROUGH FROM THE CENTRAL ATLC CLIPS THE FAR SE CARIBBEAN AND THE WINDWARD ISLANDS. A PATCH OF LOW LEVEL MOISTURE WITH EMBEDDED LIGHT SHOWERS IS MOVING ACROSS THE NORTHERN LEEWARD ISLANDS INTO THE VIRGIN ISLANDS AND EASTERN PUERTO RICO. THIS CLOUDINESS IS LIKELY ASSOCIATED WITH THE REMNANTS OF A FRONTAL BOUNDARY... ANALYZED AS A SFC TROUGH OVER THE CENTRAL ATLC ON THE 1800 UTC MAP. LOW-TOPPED TRADE WIND SHOWERS ARE SEEN OVER THE E AND CENTRAL CARIBBEAN. THE COLD FRONT CURRENTLY OVER THE GULF OF MEXICO...WHICH IS MOVING RAPIDLY SE WILL MERGE WITH THE STATIONARY FRONT OVER THE NW CARIBBEAN. THE MERGED FRONT WILL CONTINUE TO MOVE SE AND STALL FROM E CUBA TO NE HONDURAS TUE AFTERNOON. ATLANTIC OCEAN... A DEEP LAYERED TROUGH OVER THE E CONUS IS APPROACHING THE W ATLC...WITH STRONG MID/UPPER LEVEL FLOW ROTATING AROUND THE BASE OF THE TROUGH INTO THE W ATLC. THESE WINDS ARE ADVECTING MID/UPPER LEVEL MOISTURE FROM THE NW CARIBBEAN AND THE SE GULF OF MEXICO INTO THE W ATLC. A MUCH DRIER AND COOLER AIRMASS WILL BEGIN TO PUSH ACROSS THE W ATLC TONIGHT...WHICH IS BEING USHERED IN BY A COLD FRONT THAT IS CURRENTLY MOVING SOUTHWARD ACROSS NORTHERN FLORIDA. FURTHER TO THE E...UPPER LEVEL ANTICYCLONIC FLOW ASSOCIATED WITH THE UPPER-LEVEL HIGH LOCATED BETWEEN HISPANIOLA AND THE SE BAHAMAS COVERS MUCH OF THE CENTRAL ATLC. ANOTHER DEEP LAYERED TROUGH ENTERS THE FORECAST AREA NEAR 31N41W THEN CONTINUES SW TO THE WINDWARD ISLANDS/FAR SE CARIBBEAN. THIS TROUGH IS SUPPORTING THE SURFACE TROUGH THAT EXTENDS ACROSS THE CENTRAL ATLC ALONG 31N42W 22N50W TO THE NORTHERN LEEWARD ISLANDS. ISOLATED SHOWERS ARE ALONG THE TROUGH AXIS. THE E ATLC...WHERE GENERALLY FAIR WEATHER CONDITIONS PREDOMINATE...IS UNDER THE INFLUENCE OF A SFC RIDGE ANCHORED ON HIGH SITUATED WELL N OF THE AREA. AN EAST-TO-WEST UPPER-LEVEL RIDGE DOMINATES THE DEEP TROPICS...PARTICULARLY E OF 45W AND IS ENHANCING CONVECTION ALONG THE ITCZ AXIS. $$ GR