000 WTNT42 KNHC 271434 TCDAT2 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