WTPA42 PHFO 100258 TCDCP2 TROPICAL STORM FELICIA DISCUSSION NUMBER 26 NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP082009 500 PM HST SUN AUG 09 2009 DESPITE STRONG SHEAR AFFECTING FELICIA...AIR FORCE RECONNAISSANCE AIRCRAFT DATA THROUGH 0000 UTC CONTINUED TO INDICATE TROPICAL STORM FORCE WINDS IN THE NORTHERN SEMICIRCLE OF THE SYSTEM...WITH THE CENTRAL PRESSURE REMAINING LEVEL AT 1002 MB. A MAXIMUM FLIGHT-LEVEL WIND OF 56 KT AT 850 MB WAS OBSERVED 40 NM TO THE NORTHEAST OF THE CENTER. ALSO..A DROPSONDE RELEASED IN THE NORTHEAST QUADRANT AROUND 2300 UTC...BUT RADIALLY JUST INWARD FROM THE DEEPEST CONVECTION... MEASURED A MEAN BOUNDARY LAYER WIND OF 46 KT. STRONGER WINDS ARE LIKELY STILL OCCURRING WITHIN THE CONVECTION FARTHER NORTHEAST AS SHOWN BY AN EARLIER SONDE. BASED ON THESE DATA AND A SUPPORTING DVORAK CI NUMBER FROM CPHC OF 3.0...45 KT...THE INITIAL INTENSITY WILL BE HELD AT 45 KT FOR THIS FORECAST PACKAGE. SINCE THE CIRCULATION CENTER HAS BEEN FULLY EXPOSED THROUGHOUT THE DAY...THERE IS HIGH CONFIDENCE IN POSITION AND MOTION ESTIMATES... CURRENTLY 280 DEG AT 12 KT. FELICIA IS A SHEARED SYSTEM AND ITS MOTION IS PRIMARILY UNDER THE INFLUENCE OF THE LOWER LEVEL EASTERLY FLOW. HOWEVER...THERE IS STILL A FAIR AMOUNT OF DISPARITY BETWEEN THE TRUSTED DYNAMICAL MODELS REGARDING TRACK. THE GFS AND ECMWF KEEP FELICIA NORTH OF THE STATE. GFDL AND HWRF CLIP THE NORTHERN HALF OF THE ISLAND CHAIN AND NOGAPS IS THE SOUTHERN TRACK IN THE GROUP. NONE OF THE OBJECTIVE AIDS PUT THE CENTER OF FELICIA OVER THE BIG ISLAND. THIS DIFFERENCE IN TRACK HAS SIGNIFICANT IMPACTS ON EXPECTED CONDITIONS IN THE HAWAIIAN ISLANDS. THE GFS AND ECMWF SOLUTION TRANSLATES TO MUCH LOWER WIND SPEEDS ACROSS THE STATE. THE REMAINING FORECAST AIDS SUGGEST STRONGER WIND AND RAINFALL IMPACTS...ESPECIALLY FROM MAUI WESTWARD TO KAUAI. IT IS EXPECTED THAT FELICIA WILL REMAIN UNDER THE INFLUENCE OF THE LOW LEVEL EASTERLIES AS A SHEARED SYSTEM OVER THE NEXT 2 TO 3 DAYS. THIS PUTS THE TRACK DOWN THE MID-SECTION OF THE STATE AND IS CONSISTENT WITH BOTH THE PREVIOUS FORECAST PACKAGE AND THE DYNAMICAL MODEL CONSENSUS. IN TERMS OF THE LARGER SCALE UPPER LEVEL PATTERN...AN ANTICYCLONE IS CENTERED ABOUT 200 MILES SOUTHEAST OF THE BIG ISLAND OF HAWAII AND A LOW IS CENTERED FAR NORTHEAST OF THE STATE. THIS HAS RESULTED IN UPPER LEVEL DIFFLUENCE OVER FELICIA WHICH HAS HELPED SUPPORT DEEP CONVECTION. AS FELICIA MOVES WESTWARD...IT WILL LEAVE THE AREA OF DIFFLUENCE AND BE UNDER STEADY HIGH LEVEL WESTERLIES OVER LOW LEVEL EASTERLIES...THUS STRONG VERTICAL SHEAR. THE PRESENCE OF THIS SHEAR SHOULD CONTINUE TO WEAKEN FELICIA DESPITE SLIGHTLY WARMING SSTS ALONG THE FORECAST TRACK. THE CURRENT FORECAST KEEPS FELICIA AT TROPICAL STORM INTENSITY THROUGH 48 HOURS...SIMILAR TO THE GFDL AND HWRF...THEN INDICATES CONTINUED WEAKENING TO A REMNANT LOW BY 120 HOURS. FORECAST POSITIONS AND MAX WINDS INITIAL 10/0300Z 21.2N 148.4W 45 KT 12HR VT 10/1200Z 21.2N 150.2W 40 KT 24HR VT 11/0000Z 21.2N 152.6W 35 KT 36HR VT 11/1200Z 21.3N 154.8W 35 KT 48HR VT 12/0000Z 21.4N 156.9W 35 KT 72HR VT 13/0000Z 21.9N 161.2W 30 KT 96HR VT 14/0000Z 22.9N 165.2W 25 KT...DISSIPATING 120HR VT 15/0000Z 24.4N 169.2W 20 KT...REMNANT LOW $$ FORECASTER KODAMA/KNABB