000 WTPZ44 KNHC 222046 TCDEP4 TROPICAL STORM FRANK DISCUSSION NUMBER 5 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP092010 200 PM PDT SUN AUG 22 2010 EVEN THOUGH CLOUD TOPS HAVE WARMED A BIT OVER THE PAST SEVERAL HOURS ...A CURVED CONVECTIVE BAND CONTINUES TO WRAP INTO THE CENTER OF FRANK. THE INITIAL INTENSITY IS RAISED TO 50 KNOTS FOR THIS PACKAGE...BASED ON A BLEND OF DVORAK ESTIMATES FROM TAFB AND SAB. DESPITE SHOWING THE SHEAR INCREASING TO 25 KNOTS BY 12 HOURS...THE STATISTICAL INTENSITY MODELS HAVE TRENDED SHARPLY UPWARD IN THE FIRST 48 HOURS IN RESPONSE TO THE CURRENT STRENGTHENING AND AN OTHERWISE FAVORABLE ENVIRONMENT. THE OFFICIAL FORECAST IS AGAIN ADJUSTED UPWARD...BUT NOW LIES A LITTLE BELOW THE SHIPS AND LGEM THROUGH DAY 2 AND CLOSE TO A BLEND OF THOSE MODELS BEYOND THAT TIME. THE INITIAL MOTION ESTIMATE IS 270/07...AND THE OVERALL SYNOPTIC REASONING REMAINS UNCHANGED. THROUGH THE PERIOD FRANK SHOULD BE STEERED PRIMARILY WESTWARD AND THEN WEST-NORTHWESTWARD BY A DEEP-LAYER RIDGE CENTERED OVER WESTERN NORTH AMERICA. WHILE ALL OF THE GLOBAL MODEL AND ENSEMBLE GUIDANCE IS IN GOOD AGREEMENT WITH THE SYNOPTIC PATTERN...THE TRACK MODEL GUIDANCE SPREAD HAS INCREASED ...ESPECIALLY IN TERMS OF THE FORWARD SPEED OF THE CYCLONE. MOST OF THE GUIDANCE HAS TRENDED FASTER THROUGH 48 HOURS...AND THE OFFICIAL FORECAST HAS BEEN ADJUSTED IN THAT DIRECTION AND LIES NEAR THE CENTER OF THE GUIDANCE SUITE. LATE IN PERIOD THE OFFICIAL FORECAST IS A LITTLE SLOWER THAN THE MULTI-MODEL CONSENSUS DUE TO THE LARGE SPREAD IN THE GUIDANCE. GIVEN THE NEW FORECAST TRACK...THE GOVERNMENT OF MEXICO HAS EXTENDED THE TROPICAL STORM WARNING WESTWARD TO ACAPULCO. FORECAST POSITIONS AND MAX WINDS INITIAL 22/2100Z 13.9N 96.0W 50 KT 12HR VT 23/0600Z 14.0N 97.2W 60 KT 24HR VT 23/1800Z 14.3N 98.8W 65 KT 36HR VT 24/0600Z 14.8N 100.4W 70 KT 48HR VT 24/1800Z 15.4N 101.7W 75 KT 72HR VT 25/1800Z 16.5N 104.0W 75 KT 96HR VT 26/1800Z 17.5N 106.5W 70 KT 120HR VT 27/1800Z 18.5N 109.5W 70 KT $$ FORECASTER BRENNAN