Tropical Storm DELTA

ZCZC MIATCDAT3 ALL
TTAA00 KNHC DDHHMM
TROPICAL STORM DELTA DISCUSSION NUMBER   4
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
10 AM EST THU NOV 24 2005
 
CONVENTIONAL AND MICROWAVE SATELLITE IMAGERY INDICATE DELTA HAS
CONTINUED TO STRENGTHEN. AN EYE FEATURE HAS BECOME BETTER DEFINED
DURING THE PAST FEW HOURS AND A 24/0826Z QUIKSCAT OVERPASS
INDICATED SEVERAL 60-KT WIND VECTORS TO THE NORTH AND SOUTH OF THE
CENTER. THESE WINDS WERE IN AREAS OF NO OR WEAK RAIN REGIONS... SO
THEY ARE CONSIDERED TO BE VALID... ESPECIALLY SINCE THOSE VECTORS
AND THE ENTIRE EYE WERE SURROUNDED BY A LARGER AREA 50-55 KT WIND
VECTORS. DELTA IS CLOSE TO BECOMING A HURRICANE... AND THE ONLY
REASON THE INTENSITY WAS HELD DOWN WAS DUE TO THE LACK OF ANY
CONVECTION IMMEDIATELY SURROUNDING AROUND THE EYE FEATURE.
 
THE INITIAL MOTION ESTIMATE 090/02 KT. WATER VAPOR IMAGERY AND
RECENT SATELLITE POSITION ESTIMATES SUGGEST THAT DELTA MAY HAVE
BOTTOMED OUT AT THE BASE OF THE LARGE TROUGH/CYCLONIC GYRE IN WHICH
THE CYCLONE IS EMBEDDED. THE MAJORITY OF THE NHC MODEL GUIDANCE
CONTINUES TO TAKE DELTA SLOWLY SOUTHWEST AND THEN WESTWARD BEFORE
TURNING IT BACK TO THE NORTH... DESPITE THE BROAD COUNTER-CLOCKWISE
MOTION THE CYCLONE HAS MAINTAINED FOR THE PAST 48 HOURS. WHILE IT
IS POSSIBLE THAT DELTA COULD MAKE SOME SMALL LOOPS OR WOBBLES TO
THE SOUTH OR SOUTHWEST... THE OFFICIAL FORECAST CALLS FOR LITTLE
MOTION FOR THE NEXT 24 HOURS. THE CYCLONE IS EXPECTED TO TURN BACK
TO THE NORTH BY 36 HOURS. THE OFFICIAL TRACK IS A LITTLE TO THE
EAST OF THE PREVIOUS ADVISORY FOR THE FIRST 36 HOURS TO ACCOUNT FOR
THE MORE EASTWARD INITIAL POSITION... BUT THEN COMES BACK ON TRACK
BY 72-120 HOURS. A NORTHWESTWARD TURN BY 120H IS EXPECTED DUE TO 
SOME BINARY INTERACTION WITH AN EXTRATROPICAL LOW PRESSURE SYSTEM
THAT IS FORECAST TO DEVELOP TO THE WEST OF DELTA.

DELTA IS CURRENTLY LOCATED BENEATH AN UPPER-LEVEL SHEAR AXIS ALONG
38-39N LATITUDE. THIS HAS ALLOWED FOR THE VERTICAL SHEAR TO
DECREASE AND FOR ANTICYCLONIC OUTFLOW TO DEVELOP. THE 300 MB WINDS
ARE DEPICTED BY ALL THE GLOBAL MODELS AS BEING AT LEAST 20 KT LESS
THAN THEY ARE 200 MB... SO THE SHIPS MODEL VERTICAL SHEAR ANALYSIS
OF 42 KT APPEARS TO BE TOO STRONG. THE MODELS MAINTAIN RELATIVELY
WEAK 300 MB WINDS OVER DELTA FOR THE NEXT 24-36 HOURS... SO THERE
IS SOME OPPORTUNITY FOR THE CYCLONE TO REACH HURRICANE STATUS
BEFORE STRONGER UPPER-LEVEL WESTERLY SHEAR KICKS IN BY 48 HOURS.
 
FORECASTER STEWART

FORECAST POSITIONS AND MAX WINDS
 
INITIAL      24/1500Z 24.8N  38.8W    60 KT
 12HR VT     25/0000Z 24.8N  38.6W    65 KT
 24HR VT     25/1200Z 25.3N  38.5W    60 KT
 36HR VT     26/0000Z 25.9N  38.6W    60 KT
 48HR VT     26/1200Z 26.6N  38.7W    55 KT
 72HR VT     27/1200Z 29.0N  39.0W    55 KT
 96HR VT     28/1200Z 32.0N  40.0W    50 KT...BECOMING EXTRATROPICAL
120HR VT     29/1200Z 34.0N  41.5W    50 KT...EXTRATROPICAL

$$
NNNN