000 WTNT42 KNHC 010245 TCDAT2 TROPICAL STORM PHILIPPE DISCUSSION NUMBER 28 NWS NATIONAL HURRICANE CENTER MIAMI FL AL172011 1100 PM AST FRI SEP 30 2011 A PAIR OF MICROWAVE PASSES FROM LATE THIS AFTERNOON WERE VERY HELPFUL IN FIXING THE CENTER OF PHILIPPE AFTER THE CENTER BECAME OBSCURED...AND INDICATED THE CYCLONE WAS A LITTLE TO THE RIGHT OF THE PREVIOUS TRACK. THE INITIAL MOTION IS 320/8. THE MICROWAVE DATA ALSO SHOWED A VERY WELL-DEFINED LOW-LEVEL CONVECTIVE RING...BUT THE CURRENT INFRARED DEPICTION SUGGESTS THAT UPPER-LEVEL NORTHWESTERLY FLOW FROM OPHELIA IS BEGINNING TO TAKE A TOLL. DVORAK INTENSITY ESTIMATES FROM TAFB AND SAB WERE 45 AND 35 KT...RESPECTIVELY...AND THE ADVISORY INTENSITY IS HELD AT 45 KT. WATER VAPOR IMAGERY AND GLOBAL MODEL FORECASTS SUGGEST THAT THE NORTHWESTERLY SHEAR WILL LIKELY EXCEED 40 KT OVER THE NEXT COUPLE OF DAYS...SUCH THAT PHILIPPE COULD WELL SUFFER A BEHEADING AT THE HANDS OF OPHELIA. THE LGEM...TRADITIONALLY THE BEST INTENSITY GUIDANCE...SHOWS A SLOW DECREASE IN STRENGTH AND THE OFFICIAL FORECAST IS IN GOOD AGREEMENT WITH THIS MODEL. THE REMAINING GUIDANCE IS INEXPLICABLY INDIFFERENT TO THE SHEAR AND SHOWS LITTLE NET CHANGE IN STRENGTH. NEAR THE END OF THE FORECAST PERIOD... SHOULD PHILIPPE SURVIVE...THE SHEAR IS EXPECTED TO LESSEN AND SO THE OFFICIAL FORECAST SHOWS A LITTLE STRENGTHENING AT THAT TIME. A MID-LEVEL RIDGE IN BETWEEN THE TWO TROPICAL CYCLONES IS EXPECTED TO TURN PHILIPPE TO THE WEST-NORTHWEST AND PERHAPS WEST OVER THE NEXT COUPLE OF DAYS. HOWEVER...THE STRENGTH OF THIS TURN WILL DEPEND ON HOW MUCH CONVECTION PHILIPPE CAN MAINTAIN AS THE NORTHWESTERLY SHEAR INCREASES...WITH A WEAKER OR SHALLOWER SYSTEM MAINTAINING A NORTHWARD COMPONENT OF MOTION LONGER. BY DAY FOUR...PHILIPPE SHOULD BE APPROACHING A LARGE TROUGH OFF THE U.S. EAST COAST AND TURN NORTHWARD. MODEL GUIDANCE DIVERGES SIGNIFICANTLY AT THAT POINT...WITH THE ECMWF AND UKMET SHOWING PHILIPPE TURNING NORTHEASTWARD AND THE GFS MUCH FARTHER SOUTHWEST. THE OFFICIAL FORECAST HAS BEEN ADJUSTED TO THE RIGHT OF THE PREVIOUS FORECAST TOWARDS THE ECMWF AND SHALLOW BAM...UNDER THE ASSUMPTION THAT PHILIPPE WILL NOT BE ABLE TO MAINTAIN MUCH VERTICAL COHERENCE OVER THE NEXT TWO TO THREE DAYS. FORECAST POSITIONS AND MAX WINDS INIT 01/0300Z 24.0N 46.4W 45 KT 50 MPH 12H 01/1200Z 24.7N 47.5W 45 KT 50 MPH 24H 02/0000Z 25.5N 49.4W 40 KT 45 MPH 36H 02/1200Z 26.1N 51.5W 40 KT 45 MPH 48H 03/0000Z 26.5N 53.4W 35 KT 40 MPH 72H 04/0000Z 27.0N 57.5W 30 KT 35 MPH 96H 05/0000Z 28.0N 60.0W 30 KT 35 MPH 120H 06/0000Z 31.0N 60.0W 35 KT 40 MPH $$ FORECASTER FRANKLIN