Tropical Depression TWENTY-FOUR

ZCZC MIATCDAT4 ALL
TTAA00 KNHC DDHHMM
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
 
$$
NNNN