Tropical Storm KAREN

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TROPICAL STORM KAREN DISCUSSION NUMBER  11
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL122007
1100 AM EDT THU SEP 27 2007
 
THIS MORNING'S NOAA P-3 HURRICANE HUNTER EXPERIMENTAL MISSION
REVEALED AN SFMR MAXIMUM SURFACE WIND OF 56 KT...A MAXIMUM FLIGHT
LEVEL WIND OF 57 KT ABOUT 120 NM EAST OF THE EXPOSED SURFACE
CIRCULATION...AND ANOTHER PEAK WIND ABOUT 20 NM NORTHWEST OF THE
CENTER.  THE WIND PROFILE RESEMBLES LAST NIGHT'S MISSION WHICH ALSO
INDICATED AN UNUSUAL HORIZONTAL WIND PROFILE.  BASED ON THE SFMR
DATA...THE INITIAL INTENSITY REMAINS AT 55 KT.
 
THE 20 TO 30 KT SOUTHWESTERLY SHEAR IS EXPECTED TO PERSIST DURING
THE NEXT 3 DAYS...WITH ONLY A SLIGHT DECREASE THROUGH THE REMAINING
PORTION OF THE FORECAST.  THIS IS IN AGREEMENT WITH THE GLOBAL
MODELS...SHIPS...AND THE LOGISTICAL GROWTH EQUATION MODEL.  THE
OFFICIAL FORECAST CALLS FOR GRADUAL WEAKENING THROUGH THE ENTIRE
PERIOD...BUT MAINTAINING TROPICAL STORM STRENGTH.
 
THE INITIAL MOTION IS 295/10.  A DEEP-LAYERED SUBTROPICAL RIDGE
NORTH OF THE CYCLONE SHOULD INDUCE A WEST-NORTHWESTWARD MOTION
DURING THE NEXT DAY OR SO.  AFTERWARD...THERE ARE GENERALLY TWO
DYNAMICAL MODEL CLUSTERS INDICATING TWO POSSIBLE SOLUTIONS.  THE
ECMWF AND THE GFS SHOW MOTION INDICATIVE OF THE LOW- TO MID-LEVEL
STEERING FLOW...WHILE THE REMAINING MODELS REFLECT A STRONGER
TROPICAL CYCLONE AND SUGGEST A MORE NORTHWESTWARD MOTION INFLUENCED
BY AN AMPLIFYING MID- TO UPPER TROUGH.  THE OFFICIAL FORECAST IS
BASED ON THE GFS AND ECMWF SOLUTION AND IS VERY CLOSE TO THE
PREVIOUS ADVISORY.
 
NOAA BUOY 41041 REPORTED A MAXIMUM 1-MINUTE WIND OF 37 KT AROUND
1300 UTC...ABOUT 80 N MI EAST-NORTHEAST OF THE ESTIMATED CENTER
LOCATION.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      27/1500Z 13.7N  47.3W    55 KT
 12HR VT     28/0000Z 14.7N  48.7W    50 KT
 24HR VT     28/1200Z 16.0N  50.6W    45 KT
 36HR VT     29/0000Z 17.0N  52.0W    45 KT
 48HR VT     29/1200Z 18.0N  53.3W    45 KT
 72HR VT     30/1200Z 19.5N  55.5W    40 KT
 96HR VT     01/1200Z 21.0N  57.0W    40 KT
120HR VT     02/1200Z 23.0N  58.5W    40 KT
 
$$
FORECASTER ROBERTS/AVILA
 
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