000 WTNT42 KNHC 260240 TCDAT2 TROPICAL STORM PHILIPPE DISCUSSION NUMBER 8 NWS NATIONAL HURRICANE CENTER MIAMI FL AL172011 1100 PM AST SUN SEP 25 2011 RECENT MICROWAVE DATA INDICATE THAT THE LOW-LEVEL CENTER OF PHILIPPE IS MOST LIKELY NEAR THE NORTHERN EDGE OF AN AREA OF CONVECTION THAT HAS PULSED A COUPLE OF TIMES SINCE THIS AFTERNOON. THE APPEARANCE OF THE CYCLONE ON CONVENTIONAL INFRARED IMAGERY IS QUITE RAGGED... AND DVORAK ESTIMATES ARE 35 KT FROM SAB AND 45 KT FROM TAFB. THE LATEST ADT ESTIMATES ARE BETWEEN 50 AND 55 KT. PHILIPPE IS BEING KEPT AT 50 KT...BUT THAT COULD BE GENEROUS. PHILIPPE IS LOCATED ON THE SOUTHWESTERN PERIPHERY OF A MID-LEVEL RIDGE THAT EXTENDS FROM MAURITANIA TO THE CAPE VERDE ISLANDS...AND ITS MOTION IS CURRENTLY 305 DEGREES AT 10 KT. OVER THE NEXT 2 DAYS...ALL OF THE GLOBAL MODELS SHOW THE RIDGE BUILDING WESTWARD AS A SHORTWAVE TROUGH ALONG 40W LIFTS NORTHEASTWARD TOWARDS THE AZORES. THIS SHOULD KEEP PHILIPPE ON A NORTHWESTWARD BUT SLOWER TRACK THROUGH 48 HOURS. THERE IS GREATER UNCERTAINTY AFTER 48 HOURS. PHILIPPE SHOULD BE MOVING INTO AN ENVIRONMENT OF STRONGER SOUTHWESTERLY SHEAR TO THE EAST OF AN UPPER-LEVEL CUT-OFF LOW BY DAY 3...BUT THE MODELS APPEAR TO DIFFER ON HOW MUCH THAT WILL AFFECT THE INTENSITY. MOST OF THE GUIDANCE MAINTAINS A DEEP VORTEX AND TURNS THE CYCLONE NORTHWARD AND NORTHEASTWARD FROM DAYS 3 THROUGH 5 IN RESPONSE TO AN AMPLIFYING LONGWAVE TROUGH NEAR THE AZORES. HOWEVER...THE ECMWF MAINTAINS A NORTHWESTWARD MOTION DURING THAT TIME...PRESUMABLY BECAUSE IT HAS PHILIPPE DEGENERATING INTO A TROUGH AND BEING STEERED BY LOWER-LEVEL FLOW. ASSUMING THAT THE REAL STORY WILL END UP BEING SOMEWHERE BETWEEN THESE TWO SCENARIOS...THE NHC TRACK FORECAST IS ON THE WEST SIDE OF THE MAIN CLUSTER OF MODELS BUT SLOWER THAN THE TVCA CONSENSUS TO GIVE SOME CREDENCE TO THE WEAKER ECMWF. THE OFFICIAL INTENSITY FORECAST NO LONGER SHOWS PHILIPPE REACHING HURRICANE STATUS...BUT IT STILL SHOWS STRENGTHENING AND IS HIGHER THAN ALL OF THE MAIN INTENSITY MODELS THROUGH 48 HOURS. GRADUAL WEAKENING IS ANTICIPATED AFTER 48 HOURS AS PHILIPPE MOVES OVER INCREASINGLY COOLER WATERS AND IS AFFECTED BY STRONGER SHEAR. FORECAST POSITIONS AND MAX WINDS INIT 26/0300Z 14.1N 32.5W 50 KT 60 MPH 12H 26/1200Z 15.0N 33.8W 55 KT 65 MPH 24H 27/0000Z 16.0N 34.9W 60 KT 70 MPH 36H 27/1200Z 16.9N 35.9W 55 KT 65 MPH 48H 28/0000Z 17.8N 37.0W 55 KT 65 MPH 72H 29/0000Z 20.0N 39.5W 50 KT 60 MPH 96H 30/0000Z 23.0N 40.0W 50 KT 60 MPH 120H 01/0000Z 25.0N 40.0W 45 KT 50 MPH $$ FORECASTER BERG