000 AXNT20 KNHC 300551 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT SAT SEP 30 2006 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHEASTERN 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...WEATHER OBSERVATIONS...RADAR... AND METEOROLOGICAL ANALYSIS. BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0515 UTC. ...SPECIAL FEATURES... THE CENTER OF TROPICAL STORM ISAAC AT 30/0300 UTC IS NEAR 30.1N 57.4W MOVING WEST-NORTHWEST 7 KT. THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 995 MB. THE MAXIMUM SUSTAINED WIND SPEEDS ARE 60 KT WITH GUSTS TO 75 KT. PLEASE READ THE LATEST NHC FORECAST/ ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC AND THE PUBLIC ADVISORY UNDER MIATCPAT4/WTNT34 KNHC FOR MORE DETAILS. THE CLOUD PATTERN HAS BECOME A LITTLE BETTER ORGANIZED AND MORE TYPICAL OF A TROPICAL STORM. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS ON THE NORTHERN SEMICIRCLE FROM 30N-32N BETWEEN 56W-59W. ACCORDING TO ALL INTENSITY MODELS...ISAAC COULD BECOME THE FIFTH HURRICANE OF THE SEASON TODAY. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 30/31W SOUTH OF 20N MOVING WEST 10 KT. A CYCLONIC TURNING IS SEEN AT LOW LEVELS. SCATTERED SHOWERS ARE ON THE NORTHERN END OF THE WAVE AXIS AND WITHIN THE ITCZ. TROPICAL WAVE IS ALONG 56W SOUTH OF 14N MOVING WEST 10 KT. SCATTERED SHOWERS AND ISOLATED TSTMS ARE AHEAD OF THE WAVE A AXIS FROM 10N-14N BETWEEN 56W-61W. A TROPICAL WAVE IS OVER THE U.S VIRGIN ISLANDS ALONG 65/66W MOVING WEST AT 10 TO 15 KT. THIS WAVE WILL MOVE ACROSS PUERTO RICO TONIGHT REACHING DOMINICAN REPUBLIC DURING THE MORNING HOURS. THE SAN JUAN DOPPLER RADAR IS SHOWING SCATTERED TO NUMEROUS SHOWERS WITH EMBEDDED TSTMS ACROSS THE U.S VIRGIN ISLANDS...PUERTO RICO AND COASTAL WATERS. THE HEAVIEST SHOWERS ARE OVER THE OCEAN. SCATTERED SHOWERS ARE WITHIN 60 NM OF THE WAVE AXIS. THE NORTHERN END OF THE WAVE IS INTERACTING WITH AN UPPER LOW LOCATED NEAR 22N64W. SCATTERED MODERATE CONVECTION IS FROM 24N-26W BETWEEN 62W-64W. A TROPICAL WAVE IS INLAND OVER CENTRAL AMERICA ALONG 90W SOUTH OF 18N MOVING WEST 10-15 KT. THIS WAVE EXTENDS ACROSS GUATEMALA INTO THE E PACIFIC. A CLUSTER OF MODERATE/ ISOLATED STRONG CONVECTION IS OVER THE GULF OF FONSECA AND THE EASTERN PORTION OF EL SALVADOR. SIMILAR CONVECTION IS ALSO FOUND ALONG THE WAVE AXIS FROM 13N-15N AND ACROSS SOUTHERN MEXICO. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 10N14W 12N28W 12N35W 11N50W 10N60W. OUTSIDE THE CONVECTION MENTIONED IN THE TROPICAL WAVE SECTION... SCATTERED MODERATE CONVECTION IS ALONG THE COAST OF W AFRICA FROM 6N-11N EAST OF 17W. WIDELY SCATTERED MODERATE CONVECTION IS FROM 4N-10N BETWEEN 18W-28W. ...DISCUSSION... THE GULF OF MEXICO... AS OF 0300 UTC...A COLD FRONT ENTERS THE AREA NEAR 31N72W THEN CONTINUES SOUTHWESTWARD ACROSS CENTRAL FLORIDA JUST NORTH OF LAKE OKEECHOBEE. A DYING STATIONARY FRONT EXTENDS FROM CENTRAL FLORIDA TO SE TEXAS ALONG 27N82W 27N90W 29N95W. A NARROW LINE OF CLOUDS WITH ISOLATED SHOWERS IS ASSOCIATED WITH THE FRONT. A PREFRONTAL TROUGH EXTENDS FROM 30N72W TO CENTRAL CUBA NEAR 22N78W. SCATTERED MODERATE CONVECTION IS WITHIN 80/100 NM SE OF THE FRONT FROM 25N-30N. IN THE UPPER LEVELS...THE BASE OF A LONGWAVE TROUGH IS OVER THE GULF OF MEXICO MOVING E. THE FRONTAL BOUNDARY WILL CONTINUE TO DISSIPATE ACROSS THE GULF. A STRONG HIGH PRESSURE WILL BUILD OVER THE AREA BEHIND THE FRONT WITH INCREASING EASTERLY WINDS MON THROUGH WED. THE CARIBBEAN SEA... MODERATE TRADEWINDS ARE BLOWING ACROSS THE BASIN. WIDELY SCATTERED MODERATE CONVECTION IS OVER THE NW CARIBBEAN WEST OF 80W. AN UPPER HIGH IS NEAR 10N86W. A RIDGE EXTENDS NE FROM THIS ANTICYCLONE ACROSS THE NW CARIBBEAN...CUBA AND THE BAHAMAS TO 27N68W. THIS FEATURE ALSO COVERS CENTRAL AMERICA. AN UPPER LOW IS CENTERED OVER HISPANIOLA NEAR 18N68W. A TROUGH RUNS FROM THE LOW TO WESTERN VENEZUELA. THE COMBINATION OF THIS TROUGH AND THE COLOMBIAN LOW IS GENERATING CLUSTERS OF SCATTERED MODERATE TO ISOLATED STRONG CONVECTION OVER WESTERN VENZUELA AND NORTHERN COLOMBIA. THE TRADE WINDS WILL SLIGHTLY INCREASE ON SUNDAY ACROSS THE CENTRAL CARIBBEAN...SOUTH OF 15N. THE ATLANTIC OCEAN... A COLD FRONT IS OVER THE W ATLANTIC AND EXTENDS SW TO CENTRAL FLORIDA MOSTLY VOID OF ALL CONVECTION. A PREFRONTAL TROUGH EXTENDS FROM 30N72W TO CENTRAL CUBA NEAR 22N78W. A 1017 MB HIGH IS OVER THE CAROLINAS WHILE ANOTHER ONE IS OVER SE LOUISIANA. AN UPPER TROUGH IS ENTERING THE NW CORNER OF THE AREA SUPPORTING THE COLD FRONT MENTIONED ABOVE. A RIDGE IS JUST SE OF THIS TROUGH AND EXTENDS FROM A HIGH LOCATED NEAR 10N86W ACROSS CUBA AND THE BAHAMAS. A PAIR OF UPPER LOWS ARE SEEN IN THE EAST-CENTRAL ATLC NEAR 19N42W AND 27N32W. THERE IS A REFLECTION OF THE WRN MOST OF THESE UPPER LOWS AT THE SURFACE AS A TROUGH ALONG 26N42W 20N44W. AN UPPER HIGH OVER WRN AFRICA IS DOMINATING THE MID TO UPPER LEVELS OVER THE FAR ERN ATLC. CLOUDINESS AND ISOLATED SHOWERS COVER AN AREA FROM 20N-30N SEAT OF 34W TO THE CANARY ISLANDS. $$ GR