000 AXNT20 KNHC 252353 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SAT OCT 25 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 2330 UTC. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 30W S OF 12N MOVING W NEAR 15 KT. WAVE IS EMBEDDED WITHIN THE ITCZ AND AN AREA OF DEEP LAYER MOISTURE WITH CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION FROM 7N-12N BETWEEN 28W-31W. POSITION OF AXIS COINCIDES WITH A REL VORTICITY MAXIMUM AS SEEN ON THE CIMSS WAVETRAK PRODUCT. TROPICAL WAVE IS ALONG 40W S OF 11N MOVING W NEAR 10 KT. DRY AIR ASSOCIATED WITH AN UPPER-LEVEL TROUGH OVER THE CENTRAL ATLC IS LIMITING CONVECTION IN THE VICINITY OF THE WAVE. POSITION OF AXIS IS BASED ON CONTINUITY. TROPICAL WAVE IS ALONG 62W S OF 15N MOVING W NEAR 10 KT. SFC PRESSURES OBSERVED IN THE LESSER ANTILLES ARE BEGINNING TO RISE FOLLOWING THE WAVE PASSAGE. STRONG SUBSIDENCE ALOFT IS PREVENTING CONVECTIVE DEVELOPMENT. ...THE ITCZ... ITCZ AXIS IS ANALYZED ALONG 12N16W 8N25W 7N35W 7N45W 10N60W. IN ADDITION TO CONVECTION ASSOCIATED WITH TROPICAL WAVES...ISOLATED MODERATE CONVECTION IS SOUTH OF THE AXIS FROM 5N-6N BETWEEN 39W-44W. ...DISCUSSION... GULF OF MEXICO... DENSE CLOUD COVER WITH NUMEROUS SHOWERS AND ISOLATED THUNDERSTORMS ARE OBSERVED OVER SOUTHERN FLORIDA AND THE SE GULF AHEAD OF A FRONTAL BOUNDARY. AS OF 2100 UTC...THE COLD FRONT ENTERS THE GULF NEAR EVERGLADES CITY AND STRETCHES ALONG 25N83W TO 24N86W WHERE IT BECOMES STATIONARY TO 22N88W...JUST WEST OF A 1012 MB SFC LOW CENTERED NEAR 23N87W. SOUTHERLY WINDS NEAR 10 KT AHEAD OF THE FRONT INCREASE AND BECOME NORTHERLY AT 15-20 KT BEHIND THE FRONT TO 90W. EXPECT THE FRONT TO CONTINUE MOVING TOWARD THE SE...REACHING THE FLORIDA STRAIGHTS ON SUN AND EXITING THE REGION BY SUN NIGHT. E TO NE WINDS 10-15 KT FLOW AROUND A WEAK SFC RIDGE THAT COVERS THE REMAINDER OF THE GULF. AN UPPER-LEVEL HIGH OVER THE NW CARIBBEAN CONTINUES TO SUPPLY MID-UPPER LEVEL TROPICAL MOISTURE TO THE AREA...MAINTAINING PARTLY CLOUDY CONDITIONS ACROSS THE GULF WEST OF THE FRONT. CARIBBEAN SEA... A BROAD UPPER-LEVEL RIDGE COVERS THE ENTIRE CARIBBEAN ANCHORED JUST SOUTH OF THE CAYMAN ISLANDS NEAR 19N80W. A DIFFLUENT PATTERN ON THE NW PORTION OF THIS UPPER-LEVEL HIGH IS GENERATING SCATTERED SHOWERS AND THUNDERSTORMS IN THE NW CARIBBEAN W OF 83W AND N OF 15N. LOW-LEVEL WIND SPEED CONVERGENCE IS GENERATING A SECOND AREA OF SCATTERED SHOWERS ALONG THE COASTS OF NICARAGUA AND COSTA RICA S OF 12N AND W OF 81W. STRONG UPPER-LEVEL SUBSIDENCE AND THE ASSOCIATED DRY...STABLE AIR MASS IS INHIBITING DEEP CONVECTION EAST OF 78W. MODERATE EASTERLY TRADE WINDS COVER THE BASIN. ATLANTIC OCEAN... HEAVY SHOWERS AND ISOLATED THUNDERSTORMS COVER THE W ATLC AHEAD OF A COLD FRONT THAT...AS OF 2100 UTC...ENTERS THE DISCUSSION AREA NEAR 31N77W AND EXTENDS ALONG 29N78W AND CROSSES THE FLORIDA PENINSULA NEAR WEST PALM BEACH. AS OF 1800 UTC WINDS IN THE VICINITY OF THE FRONT DECREASED BELOW GALE FORCE AND SUBSEQUENTLY THE GALE WARNING WAS DROPPED. A BROAD SFC RIDGE CONTINUES TO MAINTAIN FAIR CONDITIONS N OF 22N BETWEEN 51W-76W. FURTHER EAST...A NARROW BUT DEEP-LAYER TROUGH EXTENDS INTO THE CENTRAL ATLC AND STRETCHES SW TO THE NORTHERN LEEWARD ISLANDS. THE ASSOCIATED COLD FRONT ENTERS THE AREA NEAR 31N44W AND CONTINUES ALONG 25N50W TO 22N58W WHERE IT BECOMES STATIONARY TO 21N70W. A PRE-FRONTAL TROUGH EXTENDS FROM 26N49W TO 19N53W. SCATTERED CLOUDS ARE OBSERVED ALONG THE ENTIRE FRONTAL BOUNDARY...HOWEVER SHOWERS ARE LIMITED TO THE AREA N OF 24N WITHIN 130 NM OF THE COLD FRONT. A STABLE RIDGE ANCHORED BY A 1031 MB SFC HIGH NE OF THE AZORES COVERS THE EAST ATLC. $$ WADDINGTON