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Tropical Storm DANNY


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TROPICAL STORM DANNY DISCUSSION NUMBER   8
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL052009
500 AM EDT FRI AUG 28 2009
 
AN AIR FORCE RECONNAISSANCE PLANE HAS BEEN IN THE AREA OF DANNY
SINCE AROUND 05 UTC AND FOUND THAT DANNY IS BARELY A TROPICAL
STORM...WITH THE STRONGEST WINDS CONFINED ONLY TO THE NORTHEAST OF
THE CENTER. THE INITIAL INTENSITY HAS BEEN LOWERED TO 35 KNOTS.
AFTER SEVERAL HOURS OF THE CENTER BEING COMPLETELY EXPOSED DUE TO
STRONG WESTERLY SHEAR...A NEW ROUND OF CONVECTION HAS RECENTLY
DEVELOPED NEAR THE CENTER. THE STRONG SHEAR NEARBY MOST LIKELY WILL
REMOVE THE CONVECTION ONCE AGAIN AT ANY TIME. SINCE GLOBAL MODELS
ARE BUILDING A WEAK UPPER-LEVEL RIDGE OVER THE CYCLONE WITHIN THE
NEXT 12 TO 24 HOURS...THERE IS A SMALL OPPORTUNITY FOR SLIGHT
STRENGTHENING DURING THIS PERIOD. THEREAFTER...WITH A LARGE TROUGH
APPROACHING DANNY...THE MOST LIKELY SCENARIO IS THAT THE CYCLONE
WILL INTERACT WITH THE MID-LATITUDE TROUGH AND BEGIN THE TRANSITION
TO AN EXTRATROPICAL CYCLONE BY 48 HOURS.

THE CENTER HAS BEEN MOVING BETWEEN THE NORTHWEST AND NORTH-NORTHWEST
DURING THE PAST FEW HOURS...BUT THE BEST LONG-TERM ESTIMATE OF THE
INITIAL MOTION IS 330 DEGREES AT 8 KT. THE LARGE TROUGH ALONG THE
EASTERN UNITED STATES WILL FORCE DANNY TO MOVE TOWARD THE NORTH AND
THEN NORTHEAST WITH INCREASING FORWARD SPEED AFTER 24 HOURS. 

MOST OF THE TRACK MODELS KEEP THE CENTER OF DANNY AWAY FROM THE
UNITED STATES EAST COAST...AND SINCE THE TROPICAL STORM FORCE WINDS 
ARE CONFINED TO THE EASTERN PORTION OF THE CYCLONE...IT IS NOT
NECESSARY TO ISSUE A TROPICAL STORM WARNING FOR THE REGION
CURRENTLY UNDER A TROPICAL STORM WATCH. THE TROPICAL STORM WATCH
REMAINS IN EFFECT IN CASE THE WIND FIELD BECOMES BETTER DEFINED ON
THE WESTERN SIDE OF DANNY DURING THE NEXT SEVERAL HOURS OR THE
FORECAST UNEXPECTEDLY SHIFTS TO THE WEST.
 
  
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      28/0900Z 29.5N  74.4W    35 KT
 12HR VT     28/1800Z 31.3N  74.7W    40 KT
 24HR VT     29/0600Z 34.2N  74.0W    45 KT
 36HR VT     29/1800Z 38.5N  71.5W    40 KT
 48HR VT     30/0600Z 42.5N  67.0W    40 KT
 72HR VT     31/0600Z 47.5N  59.0W    40 KT...EXTRATROPICAL
 96HR VT     01/0600Z 52.0N  47.0W    40 KT...EXTRATROPICAL
120HR VT     02/0600Z 54.0N  26.0W    45 KT...EXTRATROPICAL
 
$$
FORECASTER AVILA
 
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