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#47418 (Received by flhurricane at: 4:31 AM 21.Sep.2005) TCDAT2 TROPICAL STORM PHILIPPE DISCUSSION NUMBER 16 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 5 AM EDT WED SEP 21 2005 SATELLITE IMAGES CONTINUE TO SHOW A DISORGANIZED CLOUD PATTERN... AS PERSISTENT WESTERLY SHEAR ASSOCIATED WITH A LARGE UPPER- TROPOSPHERIC CYCLONE CENTERED NEAR 23N 60W IMPINGES ON PHILIPPE. THE GFS HAS BEEN INDICATING THAT THE UPPER CYCLONE WILL WEAKEN... AND THAT THE SHEAR OVER PHILIPPE WILL LESSEN. THIS IS DIAGNOSED BY THE SHIPS MODEL WHICH BRINGS THE SYSTEM BACK TO HURRICANE STRENGTH IN 24-36 HOURS. GIVEN THE DIFFICULTIES THAT THE GLOBAL MODELS CAN HAVE IN PREDICTING TROPICAL UPPER-LEVEL FLOWS...I AM SOMEWHAT DUBIOUS ABOUT THE UPPER-LEVEL WINDS BECOMING MORE FAVORABLE...SO THE OFFICIAL FORECAST HAS BEEN BACKED OFF A LITTLE ON RESTRENGTHENING. BY THE END OF THE FORECAST PERIOD...PHILIPPE IS LIKELY TO BECOME ABSORBED BY A LARGE EXTRATROPICAL CYCLONE OVER THE NORTH ATLANTIC AS SUGGESTED BY THE NOGAPS AND U.K. MET OFFICE MODEL FORECAST FIELDS. IT CONTINUES TO BE A CHALLENGE TO FIND THE CENTER OF CIRCULATION... ALTHOUGH AN AMSU-B PASS FROM 0201Z SUGGESTED THAT THE CENTER WAS NOT AS FAR NORTH AS PREVIOUSLY ESTIMATED. THUS THE INITIAL MOTION ESTIMATE...350/4...IS A LITTLE SLOWER THAN BEFORE. THE SLOWER STARTING SPEED DICTATES A LITTLE SLOWER FORECAST FOR THE FIRST COUPLE OF DAYS. OTHERWISE THE OFFICIAL FORECAST IS ALONG THE SAME GENERAL PATH AS IN PREVIOUS ADVISORIES...AND CLOSE TO THE GFDL/ UKMET/NOGAPS/GFS CONSENSUS. IT IS STILL ANTICIPATED THAT PHILIPPE WILL RECURVE AND ACCELERATE NORTHEASTWARD BY DAY 4 IN RESPONSE TO A STRONG MID-LATITUDE TROUGH MOVING OFF THE CANADIAN MARITIMES. A SLIGHTLY UNSETTLING ASPECT OF THE GUIDANCE IS THE 00Z GFS RUN...WHICH DOES NOT SHOW PHILIPPE GETTING COMPLETELY PICKED UP BY THE TROUGH...AND LEAVES A PIECE OF THE SYSTEM WANDERING ABOUT IN THE SUBTROPICS. THIS SCENARIO IS REJECTED AT THE PRESENT TIME. FORECASTER PASCH FORECAST POSITIONS AND MAX WINDS INITIAL 21/0900Z 19.5N 57.5W 55 KT 12HR VT 21/1800Z 21.2N 57.8W 55 KT 24HR VT 22/0600Z 23.3N 58.2W 60 KT 36HR VT 22/1800Z 25.7N 59.0W 60 KT 48HR VT 23/0600Z 28.2N 59.6W 60 KT 72HR VT 24/0600Z 33.5N 58.0W 55 KT 96HR VT 25/0600Z 38.5N 50.0W 50 KT 120HR VT 26/0600Z...DISSIPATED |