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| #51996 (Received by flhurricane at: 4:46 AM 16.Oct.2005) TCDAT4 TROPICAL DEPRESSION TWENTY-FOUR DISCUSSION NUMBER 3 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 5 AM EDT SUN OCT 16 2005 TROPICAL DEPRESSION CONTINUES TO SLOWLY GET BETTER ORGANZIED... WITH EMPHASIS ON THE WORD SLOWLY. DEEP CONVECTION AND BANDING FEATURES HAVE INCREASED... BUT DRY MID-LEVEL AIR PUNCHING IN FROM THE NORTH HAS SPLIT THE CONVECTIVE PATTERN IN TWO. BOTH TAFB AND SAB CAME IN WITH A DVORAK SATELLITE INTENSITY ESTIMATE OF T2.5/35 KT. HOWEVER ...OFTENTIMES THE SURFACE WIND FIELD OF LARGE DEVELOPING LOW PRESSURE SYSTEMS LIKE THIS ONE WILL LAG ABOUT 12 HOURS BEHIND THE SATELLITE SIGNATURE. THEREFORE... THE INITIAL INTENSITY HAS ONLY BEEN INCREASED TO 30 KT... WHICH MAY BE A LITTLE GENEROUS BASED ON NEARBY NOAA BUOY WIND REPORTS. THE DEPRESSION HAS BEEN DRIFTING WEST TO SOUTHWESTWARD FOR THE PAST 12 HOURS... WITH A MOTION BETWEEN 240-270 DEGREES AND NO MORE THAN 3 KT. THE CYCLONE IS CAUGHT BETWEEN TWO MID-LEVEL HIGH PRESSURE CENTERS... WITH THE MORE DOMINANT ONE BEING LOCATED OVER THE CENTRAL GULF OF MEXICO. THIS WEAK WESTWARD STEERING PATTERN IS EXPECTED TO CONTINUE FOR THE NEXT 48 HOURS OR SO UNTIL A SHORTWAVE TROUGH OVER THE SOUTHERN AND CENTRAL PLAINS STATES MOVES OVER AND DOWN THE EAST SIDE OF THE MEAN LONGWAVE RIDGE AXIS THAT EXTENDS NORTHWARD FROM THE GULF HIGH CENTER THROUGH LOUISIANA AND INTO MISSOURI. THE GLOBAL MODELS HANDLES THIS FIRST SHORTWAVE DIFFERENTLY WITH THE GFDL...GFS...UKMET... AND ECMWF MODELS BEING MORE AGGRESSIVE AND MAINTAIN THIS FEATURE INTO THE SOUTHEASTERN U.S. THROUGH DAY 3... WHEREAS THE NOGAPS AND GFDN MODELS DAMPEN IT OUT AND KEEP A STRONG EAST-WEST ORIENTED RIDGE TO THE NORTH ACROSS FLORIDA AND THE GULF. IF ANYTHING... THE GLOBAL MODELS TEND TO DAMPEN THESE TYPES OF SHORTWAVES TOO MUCH... SO MY FEELING IS THAT THE GFS... GFDL... UKMET... AND ECMWF MODELS MAY NOT HAVE ENOUGH SHORTWAVE ENERGY EMERGING OVER THE SOUTHEASTERN U.S. BY DAYS 2-3 AND... THEREFORE... THE RIDGE TO THE NORTH SHOULD WEAKEN MORE THAN INDICATED BY THOSE MODELS. THE FIRST SHORTWAVE IS EXPECTED TO CREATE A SMALL WEAKNESS IN THE RIDGE OVER FLORIDA AND THE EASTERN GULF OF MEXICO. A SECOND AND STRONGER UPPER-LOW/SHORTWAVE TROUGH CURRENTLY OVER CALIFORNIA IS FORECAST BY DAY 5 TO MOVE ACROSS THE SOUTHERN PLAINS AND SOUTHEASTERN U.S. AND CREATE AN EVEN LARGER WEAKNESS IN THE RIDGE... WHICH SHOULD ALLOW THE TROPICAL CYCLONE TO MOVE NORTHWARD TOWARD WESTERN CUBA OR THE YUCATAN CHANNEL... OR POSSIBLY EVEN INTO THE SOUTHEASTERN GULF OF MEXICO BY DAY 5. THE OFFICIAL FORECAST TRACK IS A LITTLE FASTER AND TO THE LEFT...OR WEST... OF THE PREVIOUS FORECAST... BUT NOT AS FAR WEST AS THE NHC MODEL CONSENSUS DUE TO THE NEGATIVE CONTRIBUTION OF NOGAPS MODEL. MID-LEVEL DRY AIR ENTRAINMENT NOTED IN BOTH 00Z UPPER-AIR DATA ACROSS FLORIDA AND IN WATER VAPOR IMAGERY IS EXPECTED TO CONTINUE FOR THE NEXT 24 HOURS OR SO. AFTER THAT... A VERY FAVORABLE UPPER-LEVEL OUTFLOW PATTERN AND WARM SSTS OF MORE THAN 29C SHOULD ALLOW FOR STEADY INTENSIFICATION. IN FACT... THE GLOBAL MODELS MAINTAIN THE CURRENT DUAL OUTFLOW CHANNEL PATTERN FOR THE NEXT 5 DAYS... AND DECREASE THE VERTICAL SHEAR TO LESS THAN 5 KT AFTER 48 HOURS. SUCH AN ENVIRONMENTAL PATTERN IS USUALLY FAVORABLE FOR RAPID INTENSIFICATION TO OCCUR AND FOR TROPICAL CYCLONES TO BECOME MAJOR HURRICANES. THE OFFICIAL INTENSITY IS SLIGHTLY HIGHER THAN THE SHIPS MODEL... WHICH BRINGS THE CYCLONE UP TO 88 KT BY 96 HOURS. FORECASTER STEWART FORECAST POSITIONS AND MAX WINDS INITIAL 16/0900Z 17.0N 79.3W 30 KT 12HR VT 16/1800Z 16.9N 79.7W 35 KT 24HR VT 17/0600Z 16.9N 80.1W 40 KT 36HR VT 17/1800Z 17.0N 80.5W 50 KT 48HR VT 18/0600Z 17.3N 81.2W 60 KT 72HR VT 19/0600Z 18.0N 82.6W 70 KT 96HR VT 20/0600Z 19.5N 83.5W 80 KT 120HR VT 21/0600Z 22.0N 84.0W 95 KT...NEAR WESTERN CUBA |
