000 WTPZ44 KNHC 232042 TCDEP4 TROPICAL STORM FRANK DISCUSSION NUMBER 9 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP092010 200 PM PDT MON AUG 23 2010 THE INNER-CORE CONVECTION ASSOCIATED WITH FRANK HAS CONTINUED TO ERODE SINCE THE PREVIOUS ADVISORY...ALTHOUGH SOME MODEST CONVECTION HAS RECENTLY DEVELOPED OVER AND TO THE SOUTHWEST OF THE CENTER. CURRENT INTENSITY ESTIMATES WERE T3.0/45 KT FROM BOTH TAFB AND SAB AT 1800 UTC...AND THAT WILL BE THE INTENSITY FOR THIS ADVISORY. MICROWAVE AND VISIBLE SATELLITE FIX POSITIONS INDICATE FRANK HAS BEEN MOVING AT 285/08...AFTER SMOOTHING THROUGH SOME RATHER LARGE WOBBLES. THE DEEP-LAYER RIDGE TO THE NORTH OF FRANK IS FORECAST TO REMAIN STRONG ENOUGH TO KEEP THE CYCLONE MOVING IN A GENERAL WEST-NORTHWESTWARD DIRECTION THROUGHOUT THE FORECAST PERIOD. THIS MOTION IS EXPECTED TO KEEP FRANK OFFSHORE AND ON A TRACK PARALLEL THE MEXICAN COAST. BY DAY 5...A DECREASE IN FORWARD SPEED AND PERHAPS A SLIGHT TURN TOWARD THE NORTHWEST WILL BE POSSIBLE AS THE WESTERN EXTENT OF THE RIDGE IS WEAKENED BY A MID-LATITUDE TROUGH FORECAST TO DIG SOUTHWARD OFF THE COAST OF BAJA CALIFORNIA. THE OFFICIAL FORECAST TRACK IS JUST AN EXTENSION OF THE PREVIOUS ADVISORY AND A LITTLE TO THE RIGHT OF THE CONSENSUS MODEL...TVCN. THE VERTICAL WIND SHEAR ACROSS FRANK IS NOT EXPECTED TO DECREASE SIGNIFICANTLY FOR THE NEXT 36-48 HOURS. ALTHOUGH THERE WILL BE PERIODIC BURSTS OF DEEP CONVECTION...ESPECIALLY AT NIGHT...THAT COULD RESULT IN BRIEF STRENGTHENING OF THE CYCLONE...ANY SUSTAINED INTENSIFICATION IS NOT EXPECTED TO OCCUR UNTIL AFTER 48 HOURS WHEN THE SHEAR IS FORECAST BY ALL THE GLOBAL MODELS TO DECREASE TO LESS THAN 15 KT. HOWEVER...BY 120 HOURS...FRANK IS EXPECTED TO BEGIN MOVING OVER SUB-26C SSTS...WHICH SHOULD INITIATE A GRADUAL WEAKENING TREND. THE OFFICIAL INTENSITY FORECAST REMAINS A BLEND OF THE SHIPS/LGEM AND GFDL/HWRF INTENSITY MODELS THROUGH 36 HOURS... AND THEN HIGHER THAN THE MODELS AFTER THAT DUE AN EXPECTED DECREASE IN THE SHEAR. NEARBY SHIP REPORTS CONTINUE TO INDICATE FRANK POSSESSES A SMALL WIND FIELD. THEREFORE...NO CHANGES TO THE EXISTING TROPICAL STORM WATCH AND WARNING AREAS FOR THE PACIFIC COAST OF MEXICO ARE REQUIRED AT THIS TIME. FORECAST POSITIONS AND MAX WINDS INITIAL 23/2100Z 14.9N 99.3W 45 KT 12HR VT 24/0600Z 15.2N 100.5W 50 KT 24HR VT 24/1800Z 15.8N 101.9W 50 KT 36HR VT 25/0600Z 16.5N 103.5W 55 KT 48HR VT 25/1800Z 17.2N 105.1W 60 KT 72HR VT 26/1800Z 18.3N 107.8W 65 KT 96HR VT 27/1800Z 19.5N 110.5W 70 KT 120HR VT 28/1800Z 20.5N 113.0W 65 KT $$ FORECASTER STEWART