Tropical Storm DELTA

ZCZC MIATCDAT3 ALL
TTAA00 KNHC DDHHMM
TROPICAL STORM DELTA DISCUSSION NUMBER   3
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
4 AM EST THU NOV 24 2005
 
INFRARED IMAGERY THIS MORNING INDICATES THAT DELTA IS A LITTLE
BETTER ORGANIZED...WITH SOMEWHAT INCREASED CONVECTIVE BANDING AND
SOME ANTICYCLONIC OUTFLOW IN THE EASTERN SEMICIRCLE.  WHILE THE
CONVECTIVE AREA ASSOCIATED WITH THE STORM IS FAIRLY SMALL...DELTA
HAS A LARGE CYCLONIC ENVELOPE PROVIDED BY ITS DEVELOPMENT AS A
NON-TROPICAL LOW.  SATELLITE INTENSITY ESTIMATES ARE 55 KT FROM
TAFB AND SAB...AND THAT IS THE INITIAL INTENSITY.  IT SHOULD BE
NOTED THAT A TRMM OVERPASS AT 0403Z SUGGESTS THE CENTER IS
NORTHEAST OF THE POSTIONS FROM TAFB AND SAB...AND IF LATER
INFORMATION CONFIRMS THIS THE POSITION AND MOTION MAY NEED SOME
ADJUSTMENT ON THE NEXT ADVISORY.

THE INITIAL MOTION IS A SOMEWHAT UNCERTAIN 155/7.  DELTA IS
CURRENTLY BEING STEERED BY A MID/UPPER-LEVEL TROUGH TO THE NORTH
AND EAST...AND A HIGH-AMPLITUDE DEEP-LAYER RIDGE TO THE WEST. 
LARGE-SCALE MODELS FORECAST THE RIDGE TO SLOWLY WEAKEN DURING THE
NEXT 48 HR AS A SHORTWAVE TROUGH CURRENTLY OVER FLORIDA MOVES
EASTWARD.  BY 72 HR...THIS TROUGH WILL BE AMPLIFYING JUST WEST OF
DELTA...WITH THE LARGE-SCALE MODELS EITHER FORMING ANOTHER AREA OF
LOW PRESSURE WEST OF THE STORM OR SPLITTING THE STORM IN TWO AS A
RESULT.  THIS PATTERN EVOLUTION SHOULD ALLOW DELTA TO CONTINUE MORE
SOUTHWARD OR SOUTHEASTWARD FOR 24 HR OR SO...FOLLOWED BY A TURN
BACK TOWARD THE NORTH AS THE RIDGE WEAKENS.  BY 72 HR...THE FALLING
PRESSURES WEST OF THE STORM SHOULD MOVE IT ALONG FASTER TOWARD THE
NORTH OR NORTH-NORTHWEST.  THE NEW FORECAST TRACK CALLS FOR DELTA
TO CONTINUE SOUTH-SOUTHEASTWARD FOR 24 HR...BUT NOT AS FAR SOUTH AS
MOST OF THE MODELS ARE SUGGESTING.  AFTER THAT...THE FORECAST CALLS
FOR A TURN TOWARD THE NORTH.  THE NEW FORECAST IS SIMILAR TO...BUT
SLOWER THAN...THE PREVIOUS FORECAST AND IS IN BEST AGREEMENT WITH
THE GFDL.

ANALYSES FROM CIMSS AT THE UNIVERSITY OF WISCONSIN INDICATE ABOUT 30
KT OF VERTICAL SHEAR OVER DELTA.  HOWEVER...THE STORM DOES NOT
APPEAR QUITE THAT BADLY SHEARED IN SATELLITE IMAGERY.  THE
LARGE-SCALE MODELS FORECAST A STRONG NORTHERLY UPPER-LEVEL JET
STREAM TO PERSIST NEAR OR JUST WEST OF DELTA THROUGH 48 HR...AND
HOW MUCH THE STORM STRENGTHENS WILL DEPEND ON HOW FAR AWAY IT CAN
STAY FROM THAT SHEAR.  BETWEEN 48-72 HR...THERE IS A CHANCE THE
SHEAR COULD DECREASE FOR A SHORT TIME AS THE NEW SHORTWAVE
AMPLIFIES WEST OF DELTA...BUT BY THAT TIME THE STORM WILL LIKELY BE
MOVING INTO COOLER SEA SURFACE TEMPERATES.  THE INTENSITY FORECAST
IS BASED ON THE PREMISE THAT DELTA WILL AVOID THE WORST OF THE
SHEAR THROUGH 72 HR...WITH SLIGHT STRENGTHENING DURING THE NEXT 24
HR FOLLOWED BY GRADUAL WEAKENING AFTER 48 HR.  AFTER 72 HR...
INCREASING SHEAR...COOLER WATERS...AND THE DEVELOPMENT OF THE NEW
LOW WEST OF DELTA COULD CAUSE THE STORM TO START EXTRATROPICAL
TRANSITION AS SHOWN IN THE FORECAST.
 
THE 12 FT SEAS HAVE BEEN EXPANDED IN THE NORTHERN SEMICIRCLE BASED
ON SHIP REPORTS.
 
FORECASTER BEVEN
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      24/0900Z 24.7N  39.8W    55 KT
 12HR VT     24/1800Z 24.2N  39.6W    55 KT
 24HR VT     25/0600Z 23.9N  39.4W    60 KT
 36HR VT     25/1800Z 24.2N  39.3W    60 KT
 48HR VT     26/0600Z 24.9N  39.4W    55 KT
 72HR VT     27/0600Z 27.0N  39.5W    55 KT
 96HR VT     28/0600Z 31.0N  40.0W    50 KT...BECOMING EXTRATROPICAL
120HR VT     29/0600Z 34.0N  41.0W    50 KT...EXTRATROPICAL
 
 
$$
NNNN