WDPN31 PGTW 220300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 30W (NOCK-TEN) WARNING NR 04// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM (TS) 30W (NOCK-TEN), LOCATED APPROXIMATELY 76 NM SOUTHEAST OF YAP, HAS TRACKED NORTHWESTWARD AT 14 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS PERSISTENT DEEP CONVECTION OBSCURING THE LOW LEVEL CIRCULATION CENTER (LLCC). A 212131Z SSMIS 91GHZ MICROWAVE IMAGE DEPICTS WELL- DEFINED LOW REFLECTIVITY BANDING WRAPPING INTO THE CENTER WITH BROKEN CURVED BANDING ALONG THE NORTHERN PERIPHERY. THE CURRENT POSITION IS EXTRAPOLATED WITH FAIR CONFIDENCE FROM THE LLCC IN THE MICROWAVE IMAGE AND POSITIONED UNDER THE EASTERN SIDE OF THE CDO FEATURE DUE TO THE EASTERLY SHEAR VECTOR. THE INTENSITY HAS BEEN INCREASED TO 40 KNOTS TO REFLECT THE INCREASED CENTRAL CONVECTION AND THE INCREASED DVORAK INTENSITY ESTIMATES RANGING FROM T2.0 TO T3.0 (30-45 KNOTS) FROM ALL AGENCIES. TS NOCK-TEN IS LOCATED IN A VERY FAVORABLE ENVIRONMENT WITH LOW (5-10 KNOTS) VERTICAL WIND SHEAR (VWS), GOOD DIVERGENT OUTFLOW, AND VERY WARM SEA SURFACE TEMPERATURES. TS 30W IS TRACKING NORTHWESTWARD ALONG THE SOUTHERN PERIPHERY OF A DEEP-LAYERED SUBTROPICAL RIDGE (STR). 3. FORECAST REASONING. A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TS 30W WILL TRACK NORTHWESTWARD ALONG THE SOUTHERN PERIPHERY OF THE STEERING STR THROUGHOUT THE FORECAST PERIOD. TS NOCK-TEN WILL CONTINUE TO INTENSIFY UNDER THE VERY FAVORABLE ENVIRONMENTAL CONDITIONS WITH THE POTENTIAL FOR A PERIOD OF RAPID INTENSIFICATION, DUE TO HIGH OCEAN HEAT CONTENT, PRIOR TO REACHING THE EASTERN COAST OF THE PHILIPPINES. DYNAMIC MODEL GUIDANCE IS IN VERY GOOD AGREEMENT, LENDING TO HIGH CONFIDENCE DURING THIS PORTION OF THE FORECAST. C. IN THE EXTENDED FORECAST, TS 30W WILL MAKE LANDFALL OVER SOUTHERN LUZON NEAR TAU 96. THE SYSTEM SHOULD WEAKEN SLIGHTLY DUE TO LAND INTERACTION JUST PRIOR TO LANDFALL; HOWEVER, IF THE TRACK SHIFTS SOUTH OVER THE CENTRAL PHILIPPINES, THE CYCLONE COULD CONTINUE TO INTENSIFY. ONCE THE SYSTEM EMERGES IN THE SOUTH CHINA SEA, MODELS DEPICT A COLD SURGE THAT WILL INCREASE THE VWS AND ADVECT COLD AND RELATIVELY DRY AIR INTO THE SYSTEM. TS 30W WILL TURN TO THE SOUTH AND WEAKEN UNDER THESE CONDITIONS. DYNAMIC MODEL GUIDANCE SHOWS A SPREAD OF 270NM AS THE CYCLONE PASSES OVER THE PHILIPPINES WITH A CONTINUED SPREAD IN THE SOUTH CHINA SEA DUE TO COMPETING FLOW AT THE SURFACE AND UPPER LEVELS. DUE TO THIS, THERE IS LOW CONFIDENCE IN THE EXTENDED PORTION OF THE FORECAST.//