000 AXNT20 KNHC 011052 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT SUN OCT 01 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... HURRICANE ISAAC IS CENTERED NEAR 33.1N 60.1W AT 01/0900 UTC MOVING NORTH-NORTHWEST AT 8 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 985 MB. MAXIMUM SUSTAINED WIND SPEED IS 75 KT WITH GUSTS TO 90 KT. SEE THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS. ISAAC STRENGTHENS SLIGHTLY AND THE RAGGED EYE CONTINUED TO BE PRESENT OVERNIGHT. A BAND OF MODERATE/STRONG CONVECTION IS SURROUNDING THE EYE. THE HURRICANE WILL BEGIN TO INTERACT WITH A LARGE MID-LATITUDE TROUGH MOVING OFF THE EAST COAST OF THE UNITED STATES AND WILL BECOME EXTRATROPICAL IN ABOUT 36 HOURS. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 38W S OF 21N MOVING W 10-15 KT. THE WAVE HAS A WEAK INVERTED-V SIGNATURE AND IS EMBEDDED WITHIN DRY AIR...THUS ONLY ISOLATED SHOWERS ARE NOTED. TROPICAL WAVE IS ALONG 64W S OF 18N MOVING W 10-15 KT. WAVE IS MOVING ACROSS THE EASTERN CARIBBEAN ENHANCING THE DEVELOPMENT OF MODERATE TO STRONG CONVECTION OVER EASTERN VENEZUELA. THE WAVE WILL PASS MAINLY SOUTH OF THE VIRGIN ISLANDS AND PUERTO RICO TODAY. THE SAN JUAN DOPPLER RADAR IS SHOWING SCATTERED TO NUMEROUS SHOWERS WITH EMBEDDED TSTMS MOVING ACROSS THE U.S. VIRGIN ISLANDS AND THE EASTERN HALF OF PUERTO RICO. TROPICAL WAVE IS ALONG 75W MOVING W AT AROUND 15 KT. THE WAVE IS INTERACTING WITH A SURFACE TROUGH OVER THE BAHAMAS GENERATING CLUSTERS OF MODERATE TO ISOLATED STRONG CONVECTION BETWEEN JAMAICA AND CUBA AND FROM 20N-25N BETWEEN 72W-75W. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 11N14W 6N25W 7N36W 11N45W 9N60W. SCATTERED MODERATE CONVECTION ARE FROM 2N-10N EAST OF 34W. ISOLATED SHOWERS ARE ELSEWHERE. ...DISCUSSION... GULF OF MEXICO... DEEP LAYERED TROUGH LIES ALONG THE EASTERN U.S. AND THE E GULF WITH THE BASE OF THE TROUGH REACHING WESTERN CUBA. BROAD UPPER HIGH ANCHORED OVER CENTRAL AMERICA EXTENDS A RIDGE ACROSS THE WESTERN HALF OF THE GULF INTO TEXAS. DRY AIR RESULTING IN MODERATE TO STRONG SUBSIDENCE DOMINATES THE GULF EAST OF 90W AND THE STATE OF FLORIDA WHILE ABUNDANT UPPER LEVEL MOISTURE IS SPREADING EWD ACROSS MEXICO AND THE WEST GULF. AS OF 0900 UTC...A 1018 MB HIGH IS OVER THE FLORIDA PANHANDLE WITH A RIDGE COVERING THE GULF. THIS IS GIVING THE MAJORITY OF THE AREA FAIR CONDITIONS THIS MORNING. HIGH PRESSURE WILL BUILD OVER THE SOUTHEAST U.S. MONDAY AND TUESDAY WITH INCREASING EASTERLY WINDS ACROSS THE GULF. CARIBBEAN SEA... BROAD UPPER RIDGE ANCHORED OVER CENTRAL AMERICA AND IN THE E PACIFIC REGION COVERS THE W CARIBBEAN W OF 73W WITH AN EXTENSION OF THE RIDGE EXTENDING ACROSS E CUBA AND THE BAHAMAS INTO THE W ATLC. A SURFACE TROUGH THAT EXTENDS ALONG 73/74W IS PRODUCING HEAVY SHOWERS/SCATTERED THUNDERSTORMS OVER THE CENTRAL-SOUTHERN BAHAMAS. AN UPPER LOW IN THE CARIBBEAN IS S OF THE MONA PASSAGE NEAR 16N68W COVERING THE REMAINDER OF THE CARIBBEAN. AN UPPER TROUGH EXTENDS FROM THE LOW TO THE ABC ISLANDS INTO VENEZUELA. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE OVER THE E CARIBBEAN E OF 70W ASSOCIATED WITH THE TROPICAL WAVE AND THE UPPER LOW/TROUGH OVER THE AREA. MODERATE TRADE WINDS ARE BLOWING ACROSS THE BASIN. ATLANTIC OCEAN... DEEP LAYERED TROUGH OVER THE E US EXTENDS INTO THE W ATLC W OF 73W. THE ASSOCIATED FRONTAL SYSTEM ENTERS THE AREA NEAR 32N68W THEN CONTINUES SW TO THE NORTHERN BAHAMAS. A SURFACE PRE-FRONTAL TROUGH EXTENDS FROM 26N72W TO 21N75W...GENERATING SCATTERED MODERATE/ISOLATED STRONG CONVECTION FROM 20N-25N BETWEEN 72W-75W. ANOTHER SURFACE TROUGH RUNS FROM 27N64W TO 21N67W. A DIFFLUENT PATTERN ALOFT IS ENHANCING THE SHOWER ACTIVITY ASSOCIATED WITH THIS TROUGH. A CUT-OFF UPPER LOW IS IN THE CENTRAL ATLC NEAR 20N48W DRIFTING WESTWARD. BROAD UPPER RIDGE COVERS THE E ATLC E OF 30W AND WESTERN AFRICA. A COLD FRONT IS APPROACHING THE E-CENTRAL ATLC FROM THE NORTH. WIDELY SCATTERED MODERATE CONVECTION IS AHEAD OF THE FRONT FROM 27N-31N BETWEEN 25W-35W. $$ GR