WTDN31 PGTW 290300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 29W (TWENTYNINE) WARNING NR 01// RMKS// /1. FOR METEOROLOGISTS 2. 6-HOUR SUMMARY AND ANALYSIS: TROPICAL DEPRESSION (TD) 29W (TWENTYNINE), LOCATED APPROXIMATELY 784 NM EAST OF MANILA, PHILIPPINES, HAS TRACKED WEST-NORTHWESTWARD AT 13 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS THAT EVEN AS THE ASSOCIATED CONVECTION REMAINED SHALLOW, THE FORMATIVE BANDS HAVE WRAPPED TIGHTER AND THE SYSTEM HAS BECOME MORE ORGANIZED AND SYMMETRICAL. THE INITIAL POSITION IS BASED ON THE MSI ANIMATION AND ON A NOTCH FEATURE ON A 282057Z SSMIS MICROWAVE IMAGE. THE INITIAL INTENSITY IS SUPPORTED BY DVORAK ESTIMATES FROM PGTW, KNES, AND RJTD. UPPER LEVEL ANALYSIS INDICATES THE SYSTEM IS JUST SOUTH OF THE RIDGE AXIS IN AN AREA OF LOW TO MODERATE (10-15 KNOT) VERTICAL WIND SHEAR AND GOOD POLEWARD OUTFLOW. THE CYCLONE IS TRACKING ALONG THE SOUTHERN PERIPHERY OF A WELL-ESTABLISHED SUBTROPICAL RIDGE TO THE NORTH. 3. FORECAST REASONING: A. THIS IS THE INITIAL PROGNOSTIC REASONING AND SETS THE FORECAST PHILOSOPHY. B. TD 29W WILL PROCEED GENERALLY WESTWARD THROUGHOUT ITS LIFESPAN, STEERED BY THE STR. FAVORABLE UPPER LEVEL CONDITIONS, IN ADDITION TO PERENIALLY WARM SEA SURFACE TEMPERATURES IN THE PHILIPPINE SEA WILL ENSURE STEADY INTENSIFICATION. BY TAU 48, THE SYSTEM WILL BE AT TYPHOON STRENGTH AND POISED TO CROSS THE ISLAND OF LUZON. BEFORE TAU 72, 29W WILL EMERGE IN THE SOUTH CHINA SEA AND REACH A PEAK INTENSITY OF 70 KNOTS. C. BEYOND TAU 72, THE SYSTEM WILL CROSS HAINAN, CHINA, AND THE GULF OF TONKIN BEFORE MAKING LANDFALL NEAR HANOI, VIETNAM, BY TAU 12O. INTERACTION WITH THE TOPOGRAPHY OF HAINAN AND VIETNAM WILL GRADUALLY ERODE THE SYSTEM. THE LIMITED NUMERIC MODEL GUIDANCE IS IN TIGHT AGREEMENT - UNUSUAL FOR A DEVELOPING CYCLONE - BUT, GIVEN THE FORMATIVE STAGE OF THE SYSTEM, THERE IS LOW CONFIDENCE IN THE JTWC FORECAST. // NNNN NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 285 DEG/ 15 KTS --- 72 HRS, VALID AT: 010000Z --- 18.0N 117.0E MAX SUSTAINED WINDS - 070 KT, GUSTS 085 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 025 NM NORTHEAST QUADRANT 020 NM SOUTHEAST QUADRANT 020 NM SOUTHWEST QUADRANT 025 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 045 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 045 NM SOUTHWEST QUADRANT 045 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 115 NM NORTHEAST QUADRANT 105 NM SOUTHEAST QUADRANT 110 NM SOUTHWEST QUADRANT 115 NM NORTHWEST QUADRANT VECTOR TO 96 HR POSIT: 285 DEG/ 14 KTS --- LONG RANGE OUTLOOK: --- 96 HRS, VALID AT: 020000Z --- 19.2N 111.1E MAX SUSTAINED WINDS - 070 KT, GUSTS 085 KT WIND RADII VALID OVER OPEN WATER ONLY VECTOR TO 120 HR POSIT: 290 DEG/ 11 KTS --- 120 HRS, VALID AT: 030000Z --- 20.6N 106.6E MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT WIND RADII VALID OVER OPEN WATER ONLY --- REMARKS: 290300Z POSITION NEAR 15.3N 133.8E. TROPICAL DEPRESSION 29W (TWENTYNINE), LOCATED APPROXIMATELY 784 NM EASTW OF MANILA, PHILIPPINES, HAS TRACKED WEST-NORTHWESTWARD AT 13 KNOTS OVER THE PAST SIX HOURS. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 290000Z IS 10 FEET. NEXT WARNINGS AT 290900Z, 291500Z, 292100Z AND 300300Z. THIS WARNING SUPERSEDES AND CANCELS REF A, JOINT TYPHOON WRNCEN PEARL HARBOR HI 281051Z OCT 13 TROPICAL CYCLONE FORMATION ALERT (WTPN21 PGTW 281100). // NNNN