MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 33W (THIRTYTHREE) WARNING NR 09// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL DEPRESSION 33W (THIRTYTHREE), LOCATED APPROXIMATELY 427 NM NORTHWEST OF SONSOROL, HAS TRACKED NORTHWESTWARD AT 04 KNOTS OVER THE PAST SIX HOURS. THE INITIAL POSITION IS PLACED WITH FAIR CONFIDENCE BASED ON ANIMATED MULTISPECTRAL SATELLITE IMAGERY WHICH SHOWS AN ELONGATED, PARTIALLY EXPOSED LOW-LEVEL CIRCULATION CENTER (LLCC) WITH DEEP CONVECTION SHEARED TO THE NORTHWEST. THE ENVIRONMENT IS MARGINAL WITH GOOD EQUATORWARD AND POLEWARD OUTFLOW CHANNELS AND WARM (28-29 CELSIUS) SEA SURFACE TEMPERATURE BEING OFFSET BY MODERATE TO HIGH VERTICAL WIND SHEAR (20-25 KNOTS). TD 33W IS TRACKING WESTWARD ALONG THE SOUTHERN EDGE OF A SUBTROPICAL RIDGE (STR). 3. FORECAST REASONING. A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. THROUGH TAU 72, TD 33W IS EXPECTED TO CONTINUE TRACKING WESTWARD ALONG THE SOUTHERN PERIPHERY OF THE STR. THROUGH TAU 24, MODERATE VWS AND LAND INTERACTION WILL MAINTAIN THE INTENSITY AT 30 KNOTS. AFTER TAU 24, TD 33W WILL TRACK OVER THE SULU SEA AND BEGIN TO INTENSIFY SLOWLY TO A PEAK OF 55 KNOTS BY TAU 72. DYNAMIC MODEL GUIDANCE IS IN GOOD AGREEMENT (TAU 72 SPREAD IS ABOUT 165 NM), LENDING FAIR CONFIDENCE IN THIS PORTION OF THE JTWC TRACK FORECAST. C. AFTER TAU 72, TD 33W WILL BEGIN TO SLOWLY TURN POLEWARD AS IT ROUNDS THE STR AXIS. DURING THIS PERIOD, THE TROPICAL CYCLONE WILL WEAKEN DUE TO HIGH VWS AND LAND INTERACTION AFTER IT MAKES LANDFALL OVER VIETNAM (ABOUT TAU 108). IN THE LATER TAUS, MODEL SPREAD GROWS SIGNIFICANTLY AS DIFFERENCES IN THE ORIENTATION AND INTENSITY OF THE STR CAUSE DIFFERENCES IN THE MODEL FORECAST TRACKS. THEREFORE, THERE IS LOW CONFIDENCE IN THE JTWC TRACK FORECAST WHICH IS PLACED CLOSED TO THE MODEL CONSENSUS.// NNNN NNNN