MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 01W (VONGFONG) WARNING NR 010// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON (TY) 01W (VONGFONG), LOCATED APPROXIMATELY 339 NM EAST-SOUTHEAST OF MANILA, PHILIPPINES, HAS TRACKED WESTWARD AT 09 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTI-SPECTRAL VISIBLE SATELLITE IMAGERY INDICATES THE INTENSIFICATION TREND HAS STALLED, WITH THE EYE BECOMING MORE RAGGED AND INTERMITTENTLY PARTIALLY FILLING. VONGFONG HAS CONTINUED TO TRACK ALMOST DUE WEST, WITH LANDFALL OVER EASTERN SAMAR EXPECTED WITHIN THE NEXT FEW HOURS. A TUTT CELL OVER THE SOUTH CHINA SEA (SCS) MAY BE HELPING TO AMPLIFY RIDGING TO THE NORTH MORE THAN PREVIOUSLY EXPECTED, RESULTING IN THE CONTINUED WESTWARD MOTION. A 132101Z SSMIS PASS REVEALED A LARGE SWATH OF DEEP CONVECTION AROUND THE NORTHERN SEMI-CIRCLE, WHILE THE CORE CONVECTION ALONG THE SOUTHERN SIDE OF THE MICROWAVE EYE WAS DEGRADED. A SMAP PARTIAL PASS HELPED ESTABLISH THE 34 KNOT WIND RADII ALONG THE EASTERN SEMI-CIRCLE. THE INITIAL INTENSITY WAS LOWERED SLIGHTLY TO 95 KNOTS, IN AGREEMENT WITH ADT AND CONSISTENT WITH DVORAK CURRENT INTENSITY ESTIMATES OF T5.0 FROM PGTW AND RJTD. THE INITIAL POSITION WAS PLACED WITH HIGH CONFIDENCE BASED ON EYE FIXES FROM MULTIPLE AGENCIES. THE ENVIRONMENT REMAINS FAVORABLE WITH ROBUST RADIAL OUTFLOW AND WARM SSTS PARTIALLY OFFSETTING MID-LEVEL DRY AIR. TY VONGFONG IS BEING STEERED BY A DEEP-LAYER SUBTROPICAL RIDGE POSITIONED TO THE EAST NEAR GUAM WHICH IS EXTENDING WEST TOWARD THE LUZON STRAIT. 3. FORECAST REASONING. A. THERE HAS BEEN NO SIGNIFICANT CHANGE TO THE GENERAL TRACK FORECAST PHILOSOPHY, HOWEVER, DUE TO A WESTWARD SHIFT IN TRACK OVER LAND THE INTENSITY FORECAST HAS BEEN LOWERED SIGNIFICANTLY. ADDITIONALLY, THE TAU 96 AND 120 FORECAST POSITIONS HAVE BEEN MOVED BACK SLIGHTLY DUE TO THE TRACK SHIFT. B. TY VONGFONG IS EXPECTED TO GRADUALLY SHIFT TO A WEST-NORTHWEST AND THEN NORTHWESTWARD TRACK OVER THE NEXT 24-36 HOURS AS THE TUTT CELL OVER THE SCS WEAKENS AND MOVES SOUTH, ALLOWING THE EXTENSION OF THE STEERING RIDGE TO RECEDE BACK TO THE EAST. AS A RESULT OF THE ADDITIONAL WESTWARD MOTION OVER THE PAST SIX HOURS, THE TRACK HAS BEEN SHIFTED WESTWARD TOWARDS THE MULTI-MODEL CONSENSUS SOLUTION. AFTER TAU 36, TY 01W SHOULD BEGIN TO ROUND THE RIDGE AND TURN MORE NORTHWARD. LITTLE ADDITIONAL INTENSIFICATION IS EXPECTED IN THE FEW HOURS PRIOR TO LANDFALL. A SLOW WEAKENING TREND IS FORECAST AS VONGFONG TRAVELS OVER THE MARITIME CONTINENT AS FAVORABLE CONDITIONS OFFSET FRICTIONAL EFFECTS OF THE ISLANDS. A MORE PRONOUNCED WEAKENING TREND IS EXPECTED BEGINNING BY TAU 36 AS THE SYSTEM TRACKS OVER LUZON. THE OFFICIAL JTWC FORECAST TRACK IS NOW HEDGED CLOSE TO THE CONSENSUS TRACK, WHICH TAKES INTO ACCOUNT THE MORE WESTERLY UKMET SOLUTION. DUE TO UNCERTAINTY OF WHEN THE NORTHWARD TURN WILL OCCUR OVERALL CONFIDENCE IS POOR FOR THIS PORTION OF THE FORECAST. C. AFTER TAU 72, TY VONGFONG WILL COMPLETE RECURVATURE AND BEGIN A NORTHEASTWARD TRACK AFTER ENTERING THE LUZON STRAIT. INCREASING VWS (25-30 KNOTS) AS TY 01W NEARS A BAROCLINIC BOUNDARY, ALONG WITH COOLING SSTS WILL LEAD TO FURTHER WEAKENING OF THE SYSTEM TO 35 KTS BY TAU 96. AT THIS TIME, INTERACTION WITH STRONG UPPER LEVEL WESTERLY FLOW WILL CAUSE THE SYSTEM TO BEGIN EXTRATROPICAL TRANSITION, WITH FURTHER WEAKENING TO A 25 KTS SYSTEM BY TAU 120 AS IT IS FULLY ABSORBED INTO THE BAROCLINIC ZONE. THERE IS SIGNIFICANT ALONG TRACK SPREAD OF MODEL SOLUTIONS AFTER TAU 72. THE LARGE SPREAD IN MODEL GUIDANCE LENDS HIGH UNCERTAINTY DURING THIS PERIOD AND THUS LOW CONFIDENCE IN THIS PORTION OF THE JTWC FORECAST TRACK.// NNNN NNNN