MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 29W (KAMMURI) WARNING NR 021// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON (TY) 29W (KAMMURI), LOCATED APPROXIMATELY 687 NM EAST OF MANILA, PHILIPPINES, HAS TRACKED WESTWARD AT 13 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY SHOWS THAT DEEP CONVECTION REMAINS PRESENT AROUND THE LOW LEVEL CIRCULATION CENTER (LLCC) BUT THE CONVECTION HAS BECOME ASYMMETRIC. THE INITIAL POSITION IS PLACED WITH FAIR CONFIDENCE AND IS BASED ON A 301800Z HIMAWARI INFRARED SATELLITE IMAGE, WHICH SHOWS A SMALL NOTCH FEATURE. THE INITIAL INTENSITY OF 65 KNOTS IS HEDGED BELOW THE PGTW DVORAK CURRENT INTENSITY (CI) ESTIMATE OF T4.5 (77 KNOTS) BASED ON THE RAGGED STORM STRUCTURE AND AN OLDER 301209Z METOP-B ASCAT IMAGE, WHICH INDICATED 50 KNOTS. THEREFORE, THERE IS POOR CONFIDENCE IN THE INITIAL INTENSITY. ENVIRONMENTAL ANALYSIS SHOWS FAVORABLE TO NEUTRAL VERTICAL WIND SHEAR (15 TO 20 KNOTS) ALONG WITH ROBUST POLEWARD AND EQUATORWARD OUTFLOW CHANNELS. SEA SURFACE TEMPERATURES REMAIN FAVORABLE FOR DEVELOPMENT, NEAR 29 DEGREES CELSIUS. TY 29W IS TRACKING WESTWARD WHILE POSITIONED ON THE SOUTHWESTERN EDGE OF A SUBTROPICAL RIDGE (STR) WHICH IS LOCATED TO THE NORTHEAST. 3. FORECAST REASONING. A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM THE LAST PROGNOSTIC REASONING MESSAGE. B. THROUGH TAU 36, TY 29W WILL CONTINUE TO TRACK WESTWARD ALONG THE SOUTHWESTERN PERIPHERY OF THE STR AND STEADILY INTENSIFY DUE TO FAVORABLE CONDITIONS. BY TAU 48, TY 29W WILL MAKE LANDFALL IN THE CENTRAL PHILIPPINES AND STEADILY DECREASE IN INTENSITY DUE TO LAND INTERACTION. AN APPROACHING SHORTWAVE TROUGH WILL TEMPORARILY ERODE THE STR AND ALLOW A SLIGHT NORTHWESTWARD JOG IN THE TRACK. DYNAMIC MODEL TRACK GUIDANCE IS IN FAIRLY GOOD AGREEMENT. HOWEVER, DUE TO UNCERTAINTY IN THE INITIAL INTENSITY AND THE INTENSITY GUIDANCE THERE IS LOW CONFIDENCE IN THIS PORTION OF THE JTWC FORECAST TRACK. C. AFTER TAU 72, TY 29 WILL TRACK WEST-NORTHWESTWARD AS THE STR BUILDS BACK TO THE WEST AFTER THE PASSAGE OF THE SHORTWAVE TROUGH. AS TY 29W TRACKS INTO THE SOUTH CHINA SEA IT WILL QUICKLY WEAKEN AS IT BEGINS TO INTERACT WITH A STRONG NORTHEAST SURGE EVENT AND EXPERIENCE UNFAVORABLE VERTICAL WIND SHEAR. AFTER TAU 96, TY 29W WILL TURN SHARPLY SOUTHWESTWARD AS THE TRACK CONTINUES TO BE INFLUENCED BY THE SURGE EVENT. DYNAMIC MODEL GUIDANCE IS IN GOOD AGREEMENT. THEREFORE, THERE IS HIGH CONFIDENCE IN THIS PORTION OF THE JTWC FORECAST TRACK.// NNNN NNNN