MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 30W (PHANFONE) WARNING NR 019// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON (TY) 30W (PHANFONE), LOCATED APPROXIMATELY 584 NM EAST- SOUTHEAST OF DA NANG, VIETNAM, HAS TRACKED WEST-NORTHWESTWARD AT 07 KNOTS (KTS) OVER THE PAST SIX HOURS. A 10 NM, PARTIALLY CLOUD-FILLED EYE IN ANIMATED MULTISPECTRAL SATELLITE IMAGERY PROVIDES HIGH CONFIDENCE IN THE INITIAL POSITION. THE INITIAL INTENSITY FALLS BETWEEN DVORAK FIX INTENSITIES OF T4.5 (77 KTS) AND T5.0 (90 KTS) FROM RJTD AND PGTW, RESPECTIVELY. THE 34 AND 50 KT WIND RADII WERE ASSESSED USING A 260205Z METOP-B ASCAT PASS. WITH FAIR POLEWARD OUTFLOW, LOW (5-10 KT) VERTICAL WIND SHEAR (VWS), AND WARM (27-28 CELSIUS) SEA SURFACE TEMPERATURE, THE ENVIRONMENT IS MARGINALLY SUPPORTIVE. NOTABLY, THERE IS MUCH DRIER AIR JUST TO THE WEST OF THE SYSTEM, SUGGESTING THE EYE MAY BE SHORT LIVED. TY 30W IS TRACKING ALONG THE SOUTHWEST PERIPHERY OF A SUBTROPICAL RIDGE (STR). 3. FORECAST REASONING. A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TY 30W WILL CONTINUE ON A WEST-NORTHWESTWARD TRACK UNTIL TAU 72 WHEN IT DISSIPATES DUE TO DRY AIR ENTRAINMENT AND HIGH VWS. SPREAD IN THE MODEL GUIDANCE IS QUITE LARGE, REACHING 270 NM BY TAU 72. THE JTWC TRACK FORECAST IS HEDGED NORTH OF CONSENSUS, NEAR THE ECMWF AND JGSM SOLUTIONS, WITH LOW CONFIDENCE.// NNNN NNNN