WDPN31 PGTW 050300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 05W (PEIPAH) WARNING NR 09// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM 05W (PEIPAH), LOCATED APPROXIMATELY 428 NM EAST- SOUTHEAST OF KOROR, HAS TRACKED WEST-NORTHWESTWARD AT 14 KNOTS OVER THE PAST SIX HOURS. THE CURRENT POSITION IS BASED ON A RECENT PGTW SATELLITE POSITION FIX AND A 042209Z SSMIS PASS. THE CURRENT INTENSITY OF 35 KNOTS IS CONSISTENT WITH DVORAK ESTIMATES FROM KNES AND RJTD AND STRUCTURE EVIDENT IN MICROWAVE SATELLITE IMAGERY. DEEP CONVECTION HAS PERSISTED OVER THE WESTERN PORTION OF A PARTIALLY- EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC) OVER THE PAST SIX HOURS, ALTHOUGH DISPLACEMENT TO THE WEST DUE TO PERSISTENT EASTERLY VERTICAL WIND SHEAR IS EVIDENT IN THE MOST RECENT IMAGERY. THE SYSTEM REMAINS EQUATORWARD OF AN UPPER-LEVEL RIDGE AXIS, IN AN AREA OF MODERATE EASTERLY VERTICAL WIND SHEAR AND FAVORABLE WESTWARD DIFFLUENCE ALOFT. TD 05W IS TRACKING WESTWARD ALONG THE SOUTHERN PERIPHERY OF A ZONALLY-ORIENTED SUBTROPICAL STEERING RIDGE TO THE NORTH. 3. FORECAST REASONING. A. NO CHANGE TO FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TD 05W IS EXPECTED TO TRACK WEST-NORTHWESTWARD UNDER THE CONTINUED INFLUENCE OF THE SUBTROPICAL STEERING RIDGE. SLOW INTENSIFICATION IS ANTICIPATED AS PASSAGE OVER WARM WATER AND WESTWARD DIFFLUENCE VIE WITH PERSISTENT EASTERLY VERTICAL WIND SHEAR THROUGHOUT THE FORECAST PERIOD. NUMERICAL MODEL GUIDANCE REMAINS IN GENERALLY GOOD AGREEMENT WITH THE CURRENT FORECAST TRACK. THE JTWC FORECAST IS POSITIONED CLOSE TO BUT, BASED ON A STRONG AND CONTINUING STEERING INFLUENCE, SLIGHTLY AHEAD OF THE CONSENSUS TRACK FORECAST. C. TS 05W SHOULD CONTINUE TRACKING GENERALLY WESTWARD IN THE EXTENDED TAUS, GIVEN TRENDS IN THE MODEL GUIDANCE DEPICTING A CONTINUOUS ZONAL RIDGE AND THE EXPECTATION THAT TS 05W WILL REMAIN SUFFICIENTLY SHALLOW TO FOLLOW A ZONAL LOW TO MID-LEVEL FLOW PATTERN. THE SLOW INTENSIFICATION TREND WILL BE DISRUPTED AFTER 72 AS THE SYSTEM PASSES OVER LAND, ALTHOUGH VERTICAL WIND SHEAR IS EXPECTED TO RELAX SLIGHTLY AND POLEWARD OUTFLOW IMPROVE DURING THE SAME PERIOD AS A MIDLATITUDE SHORTWAVE TROUGH PASSES TO THE NORTH. BASED ON GOOD AGREEMENT AMONGST NEARLY ALL CONSENSUS MODELS IN THE NEAR AND EXTENDED TERM, CONFIDENCE IN THE CURRENT JTWC TRACK FORECAST IS HIGH.// NNNN