000 AXNT20 KNHC 301049 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1115 UTC. ...SPECIAL FEATURES... THE CENTER OF TROPICAL STORM ISAAC AT 30/0900 UTC IS NEAR 30.3N 58.0W MOVING WEST-NORTHWEST AT 6 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. ISAAC LOOKS MUCH MORE TROPICAL THAN IT DID 24 HR AGO...WITH CONVECTIVE TOPS COLDER THAN -60C NOT FAR NORTHWEST OF THE CENTER AND THE FIRST SIGNS OF A 30-35 NM WIDE EYE. A BAND OF MODERATE TO STRONG CONVECTION IS WRAPPING AROUND THE CENTER. SOME STRENGTHENING IS FORECAST DURING THE NEXT 24 HOURS...AND ISAAC COULD BECOME THE FIFTH HURRICANE OF THE SEASON LATER TODAY. INTERESTS IN BERMUDA...THE CANADIAN MARITIME PROVINCES...AND NEWFOUNDLAND SHOULD MONITOR THE PROGRESS OF ISAAC. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 31/32W 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 59W SOUTH OF 16N MOVING WEST 10 KT. SCATTERED SHOWERS AND ISOLATED TSTMS ARE MAINLY AHEAD OF THE WAVE A AXIS FROM 10N-14N BETWEEN 58W-63W. THIS WAVE IS ALREADY PRODUCING LIGHT SHOWERS OVER THE WINDWARD ISLANDS. A TROPICAL WAVE IS OVER PUERTO RICO ALONG 67W MOVING WEST AT 10 TO 15 KT. THIS WAVE WILL REACH DOMINICAN REPUBLIC THIS MORNING. ST.CROIX REPORTED HEAVY RAIN WITH THE PASSAGE OF THE WAVE. THE SAN JUAN DOPPLER RADAR IS SHOWING SCATTERED TO NUMEROUS SHOWERS WITH EMBEDDED TSTMS ACROSS THE U.S VIRGIN ISLANDS MOVING INTO THE EASTERN PORTION OF PUERTO RICO AS WELL AS ACROSS THE COASTAL WATERS. THE NORTHERN END OF THE WAVE IS INTERACTING WITH AN UPPER LOW LOCATED NEAR 20N64W. A CLUSTER OF MODERATE TO ISOLATED STRONG CONVECTION IS FROM 23N-26W BETWEEN 63W-65W. A TROPICAL WAVE IS INLAND OVER THE YUCATAN PENINSULA AND GUATEMALA INTO THE EPAC. IT AXIS LIES ALONG 91W SOUTH OF 20N MOVING WEST 10-15 KT. CLUSTERS OF MODERATE/ISOLATED STRONG CONVECTION HAS DEVELOPED ALONG THE PACIFIC COAST FROM NICARAGUA TO GUATEMALA AND OVER THE GULF OF TEHUANTEPEC. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 12N16W 12N29W 11N35W 10N45W 11N58W. OUTSIDE THE CONVECTION MENTIONED IN THE TROPICAL WAVE SECTION... SCATTERED MODERATE CONVECTION IS FROM 4N-11N EAST OF 30W. ISOLATED SHOWERS ARE SEEN ELSEWHERE. ...DISCUSSION... THE GULF OF MEXICO... AS OF 0900 UTC...A COLD FRONT ENTERS THE AREA NEAR 31N70W THEN CONTINUES SOUTHWESTWARD ACROSS SOUTH FLORIDA. DOPPLER RADAR SHOWS A LINE OF SHOWERS WITH EMBEDDED TSTMS ALONG THE FLORIDA KEYS AND JUST EAST OF THE CITY OF MIAMI OVER THE OCEAN. A PREFRONTAL TROUGH EXTENDS FROM 29N72W TO CENTRAL CUBA NEAR 22N80W. SCATTERED MODERATE CONVECTION IS BETWEEN THE COLD FRONT AND THE PREFRONTAL TROUGH. SIMILAR CONVECTION IS ALSO BETWEEN CUBA AND THE BAHAMAS. IN THE UPPER LEVELS...THE BASE OF A LONGWAVE TROUGH OVER THE EASTERN U.S. IS OVER THE GULF OF MEXICO MOVING E. ABUNDANT UPPER LEVEL MOISTURE COVERS THE MAJORITY OF MEXICO. DRY AIR IS OVER THE NORTHERN GULF WATERS. A STRONG HIGH PRESSURE WILL BUILD OVER THE AREA DURING THE NEXT FEW DAYS WITH INCREASING EASTERLY WINDS. THE CARIBBEAN SEA... MODERATE TRADEWINDS ARE BLOWING ACROSS THE CARIBBEAN SEA. WIDELY SCATTERED MODERATE CONVECTION IS OVER THE NW CARIBBEAN WEST OF 80W AND NORTH OF JAMAICA. AN UPPER HIGH SITUATED 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...SUPPORTING THE DEVELOPMENT OF MODERATE TO STRONG CONVECTION OVER THE SW CARIBBEAN...PANAMA...NORTHERN COLOMBIA AND THE GULF OF FONSECA. AN UPPER LOW IS CENTERED OVER HISPANIOLA NEAR 18N68W. A TROUGH RUNS FROM THE LOW TO WESTERN VENEZUELA. 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 ALONG 31N70W 27N76W THEN CONTINUES ACROSS THE NORTHERN BAHAMAS AND SOUTH FLORIDA. A PREFRONTAL TROUGH EXTENDS FROM 29N72W TO CENTRAL CUBA NEAR 22N80W. A RIDGE COVERS THE SE U.S. AND NORTHERN FLORIDA. 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 20N44W AND 27N32W. A SURFACE TROUGH... REFLECTION OF THE WRN MOST OF THESE UPPER LOWS GOES FROM 25N44W TO 16N47W. SOME CYCLONIC TURNING IS ALSO SEEN IN THE LOW LEVELS. OVER THIS AREA. AN UPPER RIDGE DOMINATES THE E ATLC AND WEST AFRICA. CLOUDINESS AND ISOLATED SHOWERS COVER AN AREA FROM 20N-30N EAST OF 35W TO THE CANARY ISLANDS. $$ GR