Tropical Storm DELTA

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TROPICAL STORM DELTA DISCUSSION NUMBER   5
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
4 PM EST THU NOV 24 2005
 
THE EYE FEATURE MENTIONED IN THE PREVIOUS ADVISORY HAS BECOME RAGGED
AND LESS DISTINCT DURING THE PAST FEW HOURS. WHILE IT IS POSSIBLE
THAT DELTA MAY HAVE BRIEFLY REACHED HURRICANE STRENGTH BETWEEN
14-16Z WHEN THE EYE WAS BEST DEFINED...THE INITIAL INTENSITY WILL
REMAIN AT 60 KT FOR THIS ADVISORY BASED ON A SATELLITE INTENSITY
ESTIMATE OF T3.5/55 KT FROM TAFB/SAB AND A 1638Z UW-CIMSS INTENSITY
ESTIMATE OF 978 MB AND 72 KT. WHILE THE AMSU WIND ESTIMATE IS
PROBABLY TOO HIGH FOR A HYBRID-TYPE TROPICAL CYCLONE LIKE DELTA...
THE CENTRAL PRESSURE HAS ESSENTIALLY REMAINED UNCHANGED SINCE
0519Z... SUGGESTING THAT DELTA HAS NOT STRENGTHENED MUCH... IF
ANY... SINCE THEN. A QUIKSCAT OVERPASS AT 2048Z MAY PROVIDE SOME
QUANTITATIVE WIND INFORMATION TO HELP SETTLE THIS QUESTION.
 
THE INITIAL MOTION ESTIMATE IS STATIONARY...ALTHOUGH THE CYCLONE MAY
BE DRIFTING SLOWLY SOUTHWARD AT LESS AT 1 KT. THERE REMAINS
ESSENTIALLY NO CHANGE TO THE PREVIOUS FORECAST TRACK OR REASONING.
ALL OF THE NHC MODELS...EXCEPT FOR THE UKMET MODEL... NOW DRIFT
DELTA SLOWLY SOUTH OR EASTWARD... BEFORE TURING THE CYCLONE
NORTHWARD IN 36-72 HOURS. AFTER THAT... ALL OF THE MODELS EXCEPT
NOGAPS AND THE GFDN TAKE DELTA NORTH-NORTHEAST OR NORTHEASTWARD
THROUGH 72 HOURS. NOGAPS SHOWS SOME BINARY INTERACTION OCCURRING
WITH AN EXTRATROPICAL LOW THAT IS FORECAST TO DEVELOP TO THE WEST
OF DELTA BY 96 HOURS. THE OFFICIAL FORECAST TRACK REFLECTS THIS
INTERACTION BY A SLOW TURN TOWARD THE NORTHWEST IN 96-120 HOURS.
 
DELTA HAS REMAINED BENEATH AN UPPER-LEVEL SHEAR AXIS WHERE THE
VERTICAL SHEAR IS THE LEAST. HOWEVER... CIRRUS CLOUD MOTIONS
SUGGEST THAT A SMALL UPPER-LEVEL LOW MAY HAVE SLID OVER THE TOP OF
DELTA... WHICH HAS HELPED TO SUPPRESS THE ANTICYCLONIC OUTFLOW.
WHILE THE EYE FEATURE IS LESS DISTINCT THAN EARLIER... CONVECTION
HAS ACTUALLY INCREASED SLIGHTLY AROUND THE CENTER... SO THERE IS
STILL SOME OPPORTUNITY FOR DELTA TO BRIEFLY STRENGTHEN BEFORE
SIGNIFICANT WESTERLY SHEAR INDUCES SLOW WEAKENING BY 36-48 HOURS.

FORECASTER STEWART

FORECAST POSITIONS AND MAX WINDS
 
INITIAL      24/2100Z 24.6N  38.9W    60 KT
 12HR VT     25/0600Z 25.0N  38.7W    65 KT
 24HR VT     25/1800Z 25.5N  38.8W    60 KT
 36HR VT     26/0600Z 26.2N  38.9W    60 KT
 48HR VT     26/1800Z 27.1N  39.0W    55 KT
 72HR VT     27/1800Z 29.5N  39.5W    55 KT...BECOMING EXTRATROPICAL
 96HR VT     28/1800Z 32.0N  40.0W    50 KT...EXTRATROPICAL
120HR VT     29/1800Z 34.0N  41.5W    50 KT...EXTRATROPICAL

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