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Tropical Storm KIRK


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TROPICAL STORM KIRK DISCUSSION NUMBER   6
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL112012
1100 PM AST WED AUG 29 2012
 
THE SMALL CLOUD PATTERN ASSOCIATED WITH KIRK HAS BECOME BETTER
ORGANIZED DURING THE LAST SEVERAL HOURS. DEEP CONVECTION HAS FULLY
WRAPPED AROUND THE CENTER IN THE FORM OF A CENTRAL DENSE OVERCAST.
AN EARLIER WINDSAT PASS SHOWED A CLOSED LOW-LEVEL RING OF
CONVECTION...LIKELY PORTENDING AN INTENSIFICATION PHASE. DVORAK
T-NUMBERS AT 0000 UTC WERE A CONSENSUS 3.0/45 KT. A 0056 UTC ASCAT
PASS SHOWED SEVERAL RELIABLE 45 KT WIND VECTORS. SINCE THAT
TIME...AN INTERMITTENT EYE HAS BEEN VISIBLE BUT THAT FEATURE HAS NOT
PERSISTED. THE INITIAL INTENSITY ESTIMATE IS RAISED TO 50 KT BASED
ON THE OVERALL INCREASE IN ORGANIZATION.
 
A SERIES OF MORE RELIABLE FIXES HAS YIELDED A MORE CONFIDENT INITIAL
MOTION OF 300/08.  KIRK IS ALREADY ROUNDING THE WESTERN PERIPHERY
OF A SUBTROPICAL RIDGE OVER THE EASTERN ATLANTIC...AND GLOBAL
MODELS RESPOND BY SHOWING THE CYCLONE TURNING NORTHWESTWARD AND THEN
NORTHWARD DURING THE NEXT DAY OR SO. A RAPIDLY ADVANCING SHORTWAVE
TROUGH CURRENTLY OVER THE NORTHEASTERN UNITED STATES WILL SWEEP
SOUTHEASTWARD AND ERODE THE RIDGE FURTHER IN ABOUT TWO DAYS...
LEADING TO A RECURVATURE OF KIRK INTO THE WESTERLIES.  A MORE
COMPLEX SHORTWAVE TROUGH MOVING THROUGH THE CANADIAN MARITIME
PROVINCES AROUND THAT TIME WILL CAUSE KIRK TO ACCELERATE FOR THE
REMAINDER OF THE FORECAST.  THE NEW NHC TRACK FORECAST IS SHIFTED A
BIT TO THE RIGHT...AND IS IN GOOD AGREEMENT WITH THE GENERALLY
RELIABLE GFS AND ECWMF MODEL SOLUTIONS.
 
SOUTHWESTERLY SHEAR OVER KIRK APPEARS TO BE RELAXING AND IS EXPECTED
TO REMAIN LOW FOR AT LEAST A COUPLE OF DAYS WHILE THE CYCLONE
REMAINS OVER WARM WATERS. KIRK ALSO SEEMS TO BE AT LEAST PARTIALLY
INSULATED FROM DRY AIR LURKING TO THE NORTHWEST. STRENGTHENING IS
FORECAST UNTIL WESTERLY SHEAR INCREASES IN ABOUT 72 HOURS. THE
INCREASE IN SHEAR ALONG WITH THE PASSAGE OF KIRK OF PROGRESSIVE
LOWER SEA SURFACE TEMPERATURES SHOULD LEAD TO WEAKENING AROUND THAT
TIME. GLOBAL MODELS SHOW A RAPIDLY ADVANCING FRONTAL BOUNDARY
ENCROACHING ON KIRK IN 72-96 HOURS...AND THIS FEATURE IS FORECAST
TO ABSORB THE CYCLONE IN ABOUT 96 HOURS. THE NHC INTENSITY FORECAST
IS ADJUSTED UPWARD OVER THE PREVIOUS ONE BASED ON NOT ONLY SHORT-
TERM TRENDS BUT ALSO THE LATEST GUIDANCE SHOWING A STRONGER SYSTEM.
  
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  30/0300Z 25.9N  48.3W   50 KT  60 MPH
 12H  30/1200Z 26.9N  49.4W   55 KT  65 MPH
 24H  31/0000Z 28.6N  50.5W   60 KT  70 MPH
 36H  31/1200Z 30.6N  50.8W   65 KT  75 MPH
 48H  01/0000Z 33.3N  49.7W   70 KT  80 MPH
 72H  02/0000Z 39.4N  43.7W   80 KT  90 MPH
 96H  03/0000Z 47.1N  34.9W   70 KT  80 MPH
120H  04/0000Z...DISSIPATED
 
$$
FORECASTER KIMBERLAIN
 
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