000 WTPZ41 KNHC 310849 TCDEP1 TROPICAL STORM HOWARD DISCUSSION NUMBER 3 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 2 AM PDT TUE AUG 31 2004 ENHANCED BD INFRARED SATELLITE ANIMATION AND EARLIER SSMI AND AMSR-E MICROWAVE PASSES DEPICT THAT ELEVEN-E HAS SIGNIFICANTLY BECOME BETTER ORGANIZED OVER THE PAST 6 HOURS. IMAGERY REVEALS WELL DEVELOPED BANDING FEATURES OVER THE NORTH AND SOUTH QUADRANTS AND THAT THE LOW-LEVEL CIRCULATION CENTER HAS TUCKED BENEATH THE DEEP CONVECTION. CURRENT INTENSITY ESTIMATES FROM ALL AGENCIES IS 35 KT. THE LATEST AMSU INTENSITY ESTIMATE IS 53 KT AT 993 MB. BASED ON THE AFOREMENTIONED DATA...TROPICAL DEPRESSION ELEVEN-E IS UPGRADED TO TROPICAL STORM HOWARD. BASED ON THE MICROWAVE PASSES...THE TROPICAL STORMS BEST TRACK HAS BEEN ADJUSTED ABOUT 30 NM NORTH OF THE PREVIOUS POSITIONS. INITIAL MOTION IS WEST-NORTHWESTWARD OR 300 AT 10 KT. TROPICAL STORM HOWARD IS MOVING WITHING THE SOUTHWEST PERIPHERY OF A MID-LEVEL RIDGE SITUATED OVER THE SOUTHWEST U.S. AND BAJA. A GENERALLY WEST-NORTHWESTWARD MOTION IS EXPECTED DURING THE NEXT 72 HOURS. AFTERWARD...THE RIDGE SHOULD BEGIN TO WEAKEN AS A MID-LATITUDE TROUGH APPROACHES FROM THE NORTHWEST. THIS SHOULD CAUSE HOWARD TO REDUCE IN FORWARD SPEED AND BEGIN A MORE NORTHWEST MOTION THROUGH THE REMAINING FORECAST PERIOD. THE GFS...NOGAPS...GFDL...AND THE UKMET ARE IN GOOD AGREEMENT THROUGH 72 HOURS. BEYOND DAY 3...BOTH THE NOGAPS AND THE GFS SHOW LESS OF A RESPONSE TO THE WEAKENING RIDGE WITH A SLOW NORTHWEST DRIFT AFTER DAY 4. THE GFDL...UKMET AND THE NAVY GFDN REVEAL A VERY LARGE TROPICAL CYCLONE BY 72 HOURS WHICH AGGRESSIVELY BEGINS TO ERODE THE RIDGE CREATING AN ABRUPT TURN TO THE NORTH. THE OFFICIAL FORECAST IS BASED OFF OF THE MODEL CONSENSUS THROUGH 48...THEN IS ADJUSTED SLIGHTLY TO THE LEFT OF CONU TO CONFORM WITH A BLEND OF THE NOGAPS...GFS...AND THE PREVIOUS FORECAST. THE SEA SURFACE IS WARM AND GUIDANCE SUGGESTS A WEAK VERTICAL SHEAR ENVIRONMENT THROUGH THE ENTIRE FORECAST. THEREFORE...THE INTENSITY FORECAST CALLS FOR STRENGTHENING TO HURRICANE STRENGTH IN 36 HOURS WITH FURTHER STRENGTHENING POSSIBLE THROUGH 72 HOURS. BEYOND DAY 4...THE TROPICAL CYCLONE IS FORECAST TO MOVE OVER COOLER WATERS AND COMMENCE A GRADUAL WEAKENING TREND. THIS AGREES WITH THE SHIPS AND GFDL MODELS. FORECASTER ROBERTS/BEVEN FORECAST POSITIONS AND MAX WINDS INITIAL 31/0900Z 14.0N 106.0W 35 KT 12HR VT 31/1800Z 14.8N 107.4W 45 KT 24HR VT 01/0600Z 15.9N 109.5W 55 KT 36HR VT 01/1800Z 16.8N 111.6W 65 KT 48HR VT 02/0600Z 17.6N 113.4W 75 KT 72HR VT 03/0600Z 19.3N 116.0W 75 KT 96HR VT 04/0600Z 21.0N 118.0W 60 KT 120HR VT 05/0600Z 23.0N 119.5W 50 KT $$