000 WTPZ43 KNHC 110252 TCDEP3 TROPICAL STORM HILDA DISCUSSION NUMBER 8 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 8 PM PDT SUN AUG 10 2003 THE LOW-LEVEL CIRCULATION OF HILDA HAS BECOME EXPOSED ON THE NORTH SIDE OF THE DEEP CONVECTION. THEREFORE...THE INITIAL POSITION HAS BEEN ADJUSTED FARTHER NORTH THAN ON THE PREVIOUS ADVISORY. WHILE THE LOW-LEVEL CENTER HAS BECOME PARTLY EXPOSED...THERE IS ENOUGH STRONG CONVECTION TO THE SOUTH SUCH THAT SHEAR-PATTERN SATELLITE ESTIMATES ARE STILL AT 35 KT...BUT JUST BARELY. THEREFORE...HILDA IS MAINTAINED AS A MINIMAL TROPICAL STORM FOR THIS ADVISORY. THE INITIAL MOTION ESTIMATE IS 300/13. HOWEVER...A GRADUAL TURN BACK TOWARD THE WEST IS EXPECTED TO OCCUR IN ABOUT 12 HOURS DUE TO THE STRONG SUBTROPICAL RIDGE TO THE NORTH PRODUCING MODERATE LOW-LEVEL EASTERLY STEERING FLOW. THE GFS AND UKMET MODELS TAKE HILDA SOUTHWESTWARD AFTER 48 HOURS...MAINLY DUE TO SIGNIFICANT WEAKENING OF THE CYCLONE AND SOME LOW-LEVEL RIDGING FORECAST ALONG 135W IN THE WAKE OF GUILLERMO. SINCE GUILLERMO IS EXPECTED TO REMAIN STEADY OR WEAKEN SLIGHTLY...IT IS DOUBTFUL THAT MUCH OF A SYMPATHETIC RIDGE WILL EXIST BETWEEN THE TWO CYCLONES. THE OFFICIAL FORECAST IS NORTH OF BUT SIMILAR TO THE PREVIOUS FORECAST TRACK AND CALLS FOR A WEST-NORTHWESTWARD MOTION FOR THE NEXT 12-24 HOURS...AND THEN A CONTINUED WESTWARD MOTION AFTER THAT. THIS IS SIMILAR TO THE CONSENSUS OF THE GFDL AND GFS ENSEMBLE MODELS. UNLIKE GUILLERMO...THE SHIPS INTENSITY MODEL FORECASTS HILDA TO SIGNIFICANTLY WEAKEN AFTER 72 HOURS AS THE VERTICAL SHEAR IS EXPECTED TO INCREASE TO MORE THAN 30 KT AND SSTS DROP FROM 27C DOWN TO 25C. THE OFFICIAL INTENSITY FORECAST IS SIMILAR TO THE PREVIOUS FORECAST AND BASICALLY HOLDS THE INTENSITY STEADY FOR 72 HOURS... WITH GRADUAL WEAKENING OCCURRING AFTERWARDS. THERE COULD BE SOME FLUCTUATIONS IN THE INTENSITY DEPENDING ON HOW MUCH AND HOW LONG ANY CONVECTION DEVELOPS NEAR THE LOW-LEVEL CENTER. HOWEVER... ENVIRONMENTAL CONDITIONS GENERALLY DO NOT FAVOR MORE THAN A 10 KT INCREASE...AND ARE ACTUALLY MORE CONDUCIVE FOR WEAKENING TO OCCUR. FORECASTER STEWART FORECAST POSITIONS AND MAX WINDS INITIAL 11/0300Z 17.0N 119.6W 35 KT 12HR VT 11/1200Z 17.3N 121.3W 35 KT 24HR VT 12/0000Z 17.5N 123.6W 40 KT 36HR VT 12/1200Z 17.6N 125.8W 40 KT 48HR VT 13/0000Z 17.7N 128.1W 40 KT 72HR VT 14/0000Z 17.8N 132.5W 35 KT 96HR VT 15/0000Z 18.0N 137.0W 30 KT 120HR VT 16/0000Z 18.0N 142.0W 25 KT