WDPN31 PGTW 190300 MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 06W WARNING NR 10// RMKS/ 1. FOR METEOROLOGISTS. 2. 12 HOUR SUMMARY AND ANALYSIS. A. TROPICAL STORM 06W (SIX), LOCATED APPROXIMATELY 230 NM NORTHEAST OF MANILA, PHILIPPINES, HAS TRACKED NORTH-NORTHWESTWARD AT 12 KNOTS OVER THE PAST SIX HOURS. THE CURRENT POSITION IS BASED ON RECENT MICROWAVE AND VISIBLE SATELLITE IMAGERY OF A PARTIALLY EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC). THE CURRENT INTENSITY ESTIMATE OF 35 KNOTS IS CONSISTENT WITH DVORAK T-NUMBERS OF 2.5 FROM PGTW AND KNES. TS 06W CONTINUES TO TRACK GENERALLY NORTHWEST- WARD ALONG THE SOUTHWESTERN PERIPHERY OF A SUBTROPICAL STEERING RIDGE TO THE NORTHEAST. MODERATE EASTERLY VERTICAL WIND SHEAR AND CONVERGENCE IN THE UPPER LEVEL FLOW TO THE NORTH OF TS 06W HAVE PREVENTED THE SYSTEM FROM INTENSIFYING OVER THE PAST TWELVE HOURS DESPITE PASSAGE OVER VERY WARM WATER EAST OF LUZON AND STRONG WESTWARD OUTFLOW ALOFT. THE PERSISTENT VERTICAL WIND SHEAR HAS CONFINED THE DEEPEST CONVECTION ASSOCIATED WITH TS 06W TO THE WESTERN PERIPHERY OF THE CIRCULATION. 3. FORECAST REASONING. A. THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST PHILOSOPHY FROM THE PREVIOUS ISSUANCE OF THE PROGNOSTIC REASONING MESSAGE. B. TS 06W IS EXPECTED TO CONTINUE ON A GENERALLY NORTHWESTWARD TRACK THROUGHOUT THE FORECAST PERIOD UNDER THE STEERING INFLUENCE OF THE SUBTROPICAL RIDGE TO THE NORTHEAST. THE NUMERICAL MODEL GUIDANCE DIVERGES AFTER TAU 36, WITH THE ECMWF TRACK AND JGSM TRACK SETTING THE WESTERN AND EASTERN BOUNDS OF THE MODEL ENVELOPE, RESPECTIVELY. JGSM AND WBAR SHOW TS 06W TRACKING MORE POLEWARD TOWARD TAIWAN AS A MIDLATITUDE TROUGH WEAKENS THE STEERING RIDGE TO THE NORTH OF THE SYSTEM. THE NOGAPS, GFS, UKMET, ECMWF, AND GFDN MODELS FAVOR A MORE WESTWARD TRACK UNDER THE INFLUENCE OF A MORE CONTINUOUS STEERING RIDGE. CURRENT ANALYSIS AND EXPECTED EVOLUTION OF THE SYNOPTIC PATTERN FAVOR THE MORE WESTWARD TRACK SCENARIO REPRESENTED BY THE MAJORITY OF THE MODELS. TS 06W WILL STRUGGLE TO INTENSIFY AS IT CONTENDS WITH PERSISTENT EASTERLY VERTICAL WIND SHEAR AND CONVERGENCE ALOFT, BUT PASSAGE OVER WARM WATER AND SOME IMPROVEMENT IN THE UPPER LEVEL OUTFLOW PATTERN ARE EXPECTED TO BOOST INTENSITY SLIGHTLY UNTIL TAU 72. C. IN THE EXTENDED PERIOD, TS 06W WILL CROSS INTO SOUTHEASTERN CHINA AND DISSIPATE OVER LAND. THE EXTENDED RANGE FORECAST LIES CLOSE TO THE NUMERICAL MODEL CONSENSUS.// NNNN