WDPN31 PGTW 120300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 02W (SANBA) WARNING NR 14// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM 02W (SANBA), LOCATED APPROXIMATELY 108 NM NORTH OF SONSOROL, HAS TRACKED WESTWARD AT 11 KNOTS OVER THE PAST SIX HOURS. THE INITIAL POSITION IS PLACED WITH FAIR CONFIDENCE BASED ON THE ANIMATED LOOP AND EXTRAPOLATION FROM AN 112053Z 91GHZ SSMIS MICROWAVE IMAGE. THE MICROWAVE IMAGE SHOWS WEAK BANDING WRAPPING INTO THE LOW LEVEL CIRCULATION CENTER WITH DEEP CONVECTION IN THE NORTHWEST QUADRANT. THE INITIAL INTENSITY OF 35 KNOTS IS BASED ON THE UPPER END OF MULTI-AGENCY DVORAK CURRENT INTENSITY ESTIMATES RANGING FROM T2.0 TO T2.5 (30-35 KNOTS) FROM RJTD AND PGTW RESPECTIVELY. ENVIRONMENTAL ANALYSIS INDICATES THE SYSTEM IS IN AN AREA OF LOW TO MODERATE (15-20 KNOT) VERTICAL WIND SHEAR AND IS TRACKING THROUGH AN AREA OF WARM (29 CELSIUS) SEA SURFACE TEMPERATURES. UPPER LEVEL ANALYSIS REVEALS THAT THE SYSTEM HAS STRONG POLEWARD OUTFLOW ENHANCED BY MID-LATITUDE WESTERLIES. TS 02W IS TRACKING ALONG THE SOUTHERN EXTENT OF A SUBTROPICAL RIDGE (STR) LOCATED TO THE NORTHEAST. 3. FORECAST REASONING. A. THERE IS NO CHANGE IN THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TS 02W WILL TRACK WEST-NORTHWESTWARD ALONG AN EXTENSION OF THE STEERING STR TOWARD THE SOUTHERN PHILIPPINES. THE SYSTEM IS FORECAST TO MAKE LANDFALL SHORTLY AFTER TAU 24. MARGINALLY FAVORABLE ENVIRONMENTAL CONDITIONS WILL ALLOW FOR LIMITED ADDITIONAL INTENSIFICATION UP TO 40 KNOTS PRIOR TO LANDFALL. AFTER LANDFALL, THE FRICTIONAL EFFECTS OF THE TERRAIN WILL SLIGHTLY WEAKEN THE SYSTEM. A BUILDING EXTENSION OF THE STR WILL CAUSE THE SYSTEM TO TRACK WESTWARD ACROSS MINDANAO AND EXIT INTO THE SULU SEA SHORTLY AFTER TAU 36. MARGINALLY FAVORABLE CONDITIONS OVER THE SULU SEA WILL ALLOW THE SYSTEM TO MAINTAIN WEAK TROPICAL STORM STRENGTH AND SLIGHTLY RE-INTENSIFY AS IT TRACKS SOUTH OF PUERTO PRINCESA. DYNAMIC MODEL GUIDANCE IS IN TIGHT AGREEMENT THROUGH TAU 72, LENDING HIGH CONFIDENCE IN THIS PORTION OF THE JTWC TRACK FORECAST. C. AFTER TAU 72, TS SANBA WILL TRACK MORE NORTHWESTWARD DUE TO THE STR EXTENSION RETROGRADING WHILE THE SYSTEM ROUNDS THE SOUTHWESTERN PERIPHERY OF THE STR. UNFAVORABLE CONDITIONS IN THE SOUTH CHINA SEA, SPECIFICALLY INCREASING VWS RESULTING FROM A COLD SURGE, WILL CAUSE THE SYSTEM TO GRADUALLY WEAKEN TO 30 KNOTS BY TAU 120. AVAILABLE DYNAMIC MODEL GUIDANCE SPREADS SIGNIFICANTLY IN BOTH TRACK DIRECTION AND ALONG TRACK SPEED AFTER TAU 72. THE JTWC TRACK FORECAST IS PLACED NEAR THE MULTI-MODEL CONSENSUS HOWEVER, DUE TO THE SPREAD IN MODEL GUIDANCE THERE IS LOW CONFIDENCE IN THE LONG RANGE JTWC TRACK FORECAST.// NNNN