000 AXNT20 KNHC 311800 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT SUN AUG 31 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. ...SPECIAL FEATURES... HURRICANE GUSTAV IS CENTERED NEAR 25.9N 86.6W AT 31/1800 UTC OR ABOUT 235 NM...520 KM...SOUTHEAST OF THE MOUTH OF THE MISSISSIPPI RIVER MOVING NW OR 320 DEG AT 15 KT. THIS GENERAL MOTION IS EXPECTED TO CONTINUE WITH A DECREASE IN FORWARD SPEED DURING THE NEXT COUPLE OF DAYS. ON THE FORECAST TRACK...GUSTAV SHOULD MAKE LANDFALL ON THE NORTHERN GULF COAST ON MONDAY. THE MINIMUM CENTRAL PRESSURE JUST REPORTED BY A NOAA HURRICANE HUNTER AIRCRAFT IS 962 MB. MAXIMUM SUSTAINED WIND SPEED IS 100 KT WITH HIGHER GUSTS. PLEASE SEE THE LATEST NHC FORECAST/ ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/ WTNT22 KNHC AND/OR THE PUBLIC ADVISORY MIATCPAT2/ WTNT32 KNHC FOR MORE DETAILS. GUSTAV IS AN EXTREMELY DANGEROUS CATEGORY THREE HURRICANE ON THE SAFFIR-SIMPSON HURRICANE SCALE...AND COULD REGAIN CATEGORY FOUR STRENGTH LATER TODAY OR TONIGHT. FLUCTUATIONS IN STRENGTH ARE LIKELY THEREAFTER...BUT GUSTAV IS FORECAST TO REMAIN A MAJOR HURRICANE UNTIL LANDFALL. GUSTAV IS EXPECTED TO PRODUCE TOTAL RAINFALL ACCUMULATIONS OF 6 TO 12 INCHES OVER PORTION OF LOUISIANA...SOUTHERN MISSISSIPPI AND SOUTHERN ARKANSAS...WITH ISOLATED MAXIMUM AMOUNTS OF UP TO 20 INCHES POSSIBLE THROUGH WEDNESDAY MORNING. ADDITIONAL RAINFALL AMOUNTS OF ABOUT AN INCH ARE POSSIBLE OVER FLORIDA KEYS AND SOUTH FLORIDA. TROPICAL STORM HANNA IS CENTERED NEAR 23.5N 71.1W AT 31/1800 UTC OR ABOUT 120 NM...240 KM...NORTH OF GRAND TURK ISLAND MOVING WEST AT 10 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 997 MB. HANNA HAS WEAKENED A BIT MORE. MAXIMUM SUSTAINED WIND SPEED IS NOW 40 KT WITH HIGHER GUSTS. PLEASE SEE THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT3/WTNT23 KNHC AND/OR THE PUBLIC ADVISORY MIATCPAT3/ WTNT33 KNHC FOR MORE DETAILS. A BAND OF MODERATE TO STRONG CONVECTION ASSOCIATED WITH HANNA IS APPROACHING THE SE BAHAMAS. LONG-PERIOD SWELLS FROM THIS TROPICAL CYCLONE ARE EXPECTED TO INCREASE THE RISK OF DANGEROUS RIP CURRENTS ALONG PORTIONS OF THE SOUTHEASTERN UNITED STATES COAST DURING THE NEXT COUPLE OF DAYS. A TROPICAL WAVE IS ALONG 31W/32W S OF 21N WITH A 1010 MB SURFACE LOW ALONG THE WAVE AXIS NEAR 16N. AN EARLIER QSCAT PASS CLEARLY SHOWED THE CYCLONIC CIRCULATION ASSOCIATED WITH THIS SYSTEM WITH THE STRONGEST WINDS ON THE N SEMICIRCLE. SHOWER AND TSTMS ACTIVITY HAS INCREASED WITH A CLUSTER OF MODERATE CONVECTION COVERING THE AREA FROM 18N-20N BETWEEN 31.5W-34W. CONDITIONS APPEAR TO BE CONDUCIVE FOR DEVELOPMENT AND A TROPICAL DEPRESSION COULD FORM DURING THE NEXT DAY OR TWO AS THIS SYSTEM MOVES WESTWARD AT 10 TO 15 KT. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 49W/50W S OF 25N MOVING WNW NEAR 10 KT. A 1010 MB LOW IS EMBEDDED ON THE WAVE AXIS NEAR 20.5N50W WHERE AN EXPOSED SWIRL OF LOW CLOUDS IS NOTED ON VIS SATELLITE IMAGERY. A LARGE AREA OF CLOUDINESS WITH EMBEDDED SHOWERS EXTENDS FROM 21N-31N BETWEEN 43W-50W. UPPER-LEVEL WINDS ARE FORECAST TO REMAIN UNFAVORABLE FOR DEVELOPMENT DURING THE NEXT COUPLE OF DAYS. ...THE ITCZ... THE ITCZ AXIS IS ANALYZED ALONG 11N15W 13N27W 10N34W 11N50W 10N62W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS MOVING OFF THE AFRICAN COAST FROM 9N-13N EAST OF 19W. SCATTERED MODERATE CONVECTION IS WITHIN 100 NM SE OF LINE 14N27W 10N35W 9N40W. ...DISCUSSION... GULF OF MEXICO... ALL THE ATTENTION REMAINS FOCUSED ON GUSTAV THAT IS FORECAST TO MAKE LANDFALL ALONG THE LOUISIANA COAST THIS MONDAY AS A MAJOR HURRICANE. SEE SPECIAL FEATURES FOR DETAILS. WEATHER CONDITIONS WILL GRADUALLY DETERIORATE ALONG THE NORTHERN GULF COAST BUT MAINLY FROM CAMERON LOUISIANA EWD TO THE ALABAMA-FLORIDA BORDER WHERE A HURRICANE WARNING REMAINS IN EFFECT. PREPARATIONS TO PROTECT LIFE AND PROPERTY SHOULD BE RUSHED TO COMPLETION. RAIN...WINDS AND WAVES WILL BE ON INCREASE. CURRENTLY NOAA BUOY...42003...LOCATED IN THE EASTERN GULF IS REPORTING SUSTAINED WINDS OF 50 KT AND WAVE HEIGHTS OF 34 FEET WHILE PRES HAS FALLEN TO 992 MB. OUTER RAINBANDS ASSOCIATED WITH THE OVERALL CIRCULATION OF GUSTAV WILL CONTINUE TO AFFECT THE STATE OF FLORIDA WITH THE THREAT OF ISOLATED TORNADOES. ISOLATED SHOWERS ARE SEEN ACROSS THE WESTERN HALF OF THE GULF UNDER A N-NW WIND FLOW. A MID-UPPER LEVEL RIDGE ANCHORED ON A HIGH OVER THE NW BAHAMAS IS STEERING GUSTAV NWWD. THE RIDGE COVERS THE SE CONUS...THE WESTERN ATLC WEST OF 70W...CUBA...THE EASTERN GULF AND THE FLORIDA PENINSULA. AN-UPPER-LEVEL LOW IS TO THE WEST OF GUSTAV OVER THE WESTERN GULF NEAR 24N92W PRODUCING MODERATE TO STRONG SUBSIDENCE. CARIBBEAN SEA... GUSTAV AS A POWERFUL AND DESTRUCTIVE CATEGORY FOUR HURRICANE WITH SUSTAINED WINDS OF 150 MPH...240 KM/H MOVED YESTERDAY ACROSS WESTERN CUBA DURING THE AFTERNOON AND EVENING HOURS. THIS AFTERNOON IT CONTINUES TO MOVE AWAY FROM CUBA BUT A FEW NARROW RAINBANDS ARE STILL AFFECTING THE ISLAND. SEE SPECIAL FEATURES ABOVE. ELSEWHERE...SCATTERED SHOWERS REMAIN OVER THE NRN LEEWARD ISLANDS AND THE VIRGIN ISLANDS ASSOCIATED WITH OUTER RAINBANDS OF T.S. HANNA. IN THE UPPER LEVELS...MOSTLY EASTERLY FLOW IS NOTED OVER THE CARIBBEAN MOSTLY DUE TO OUTFLOW FROM GUSTAV AND HANNA. UPPER LEVEL MOISTURE/HIGH CLOUDS ARE OVER THE CENTRAL CARIBBEAN . ATLANTIC OCEAN... T.S. HANNA AND THE TROPICAL WAVES ARE THE MAIN FEATURES IN THE TROPICAL ATLANTIC. WV IMAGERY INDICATED THAT THE UPPER-LEVEL LOW THAT HAS BEEN LIMITING THE INTENSIFICATION OF HANNA OVER THE PAST FEW DAYS HAS BEGUN TO DROP SOUTHWARD TOWARD HISPANIOLA... WHICH MAY ALLOW HANNA TO TRANSITION BACK INTO A FULL WARM CORE TROPICAL CYCLONE LATER TODAY. AN AREA OF SCATTERED MODERATE CONVECTION HAS DEVELOPED EAST OF THE LEEWARD ISLANDS LIKELY DUE TO UPPER DIFFLUENCE RELATED TO AN UPPER-LEVEL HIGH LOCATED JUST N OF PUERTO RICO. AN UPPER-LEVEL TROUGH IS TO THE EAST EXTENDING FROM AN UPPER-LEVEL LOW SITUATED NEAR 27N50W...AND IS PRODUCING STRONG SLY WINDS OVER THE TROPICAL WAVE/LOW LOCATED ALONG 49W/50W. AN UPPER LEVEL HIGH IS OVER THE E ATLANTIC NEAR 22N35W.` $$ GR