MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 17W (KAMMURI) WARNING NR 02// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL DEPRESSION (TD) 17W (KAMMURI), LOCATED APPROXIMATELY 507 NM EAST-SOUTHEAST OF IWO TO, JAPAN, HAS TRACKED NORTH-NORTHWESTWARD AT 09 KNOTS OVER THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY DEPICTS A PARTIALLY-EXPOSED, ELONGATED LOW-LEVEL CIRCULATION CENTER (LLCC) LOCATED ON THE WESTERN EDGE OF A LARGE AREA OF DEEP CONVECTION. THE INITIAL POSITION IS BASED ON THE ABOVE ANIMATION AND EXTRAPOLATED FROM RECENT MICROWAVE IMAGERY WITH POOR CONFIDENCE. THE INITIAL INTENSITY IS BASED ON DVORAK ESTIMATES FROM PGTW AND KNES. UPPER-LEVEL ANALYSIS INDICATES A GENERALLY FAVORABLE ENVIRONMENT WITH LOW VERTICAL WIND SHEAR AND GOOD POLEWARD AND SOUTHEASTWARD OUTFLOW. HOWEVER, A MID-LATITUDE TROUGH IS CAUSING SUBSIDENCE ALONG THE WESTERN FLANK OF THE SYSTEM, EXPOSING THE LLCC. TD 17W IS TRACKING ALONG THE SOUTHWESTERN PERIPHERY OF AN EXTENSION OF THE SUBTROPICAL RIDGE (STR) TO THE NORTHEAST. 3. FORECAST REASONING. A. THERE IS NO SIGNIFICANT CHANGE IN THE FORECAST PHILOSOPHY FROM THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TD 17W IS EXPECTED TO REMAIN ON ITS CURRENT TRACK UP TO TAU 72. CONTINUED FAVORABLE UPPER LEVEL CONDITIONS, IN ADDITION TO WARM SEA SURFACE TEMPERATURES, WILL PROMOTE GRADUAL INTENSIFICATION, PEAKING AT 75 KNOTS BY TAU 72 AS THE SYSTEM BECOMES EXPOSED TO THE MID-LATITUDE WESTERLIES. C. IN THE EXTENDED TAUS, TD 17W SHOULD ROUND THE WESTERN EDGE OF THE STR AND RE-CURVE NORTHEASTWARD INTO THE MIDLATITUDE WESTERLIES AND BEGIN EXTRA-TROPICAL TRANSITION (ETT). THE CYCLONE WILL GRADUALLY WEAKEN AS IT INTERACTS WITH THE COLD BAROCLINIC ZONE. BY END OF FORECAST, THE SYSTEM WILL BECOME A STORM-FORCE COLD CORE LOW. OVERALL, THERE IS LOW CONFIDENCE IN THE JTWC TRACK FORECAST DUE TO INITIAL POSITIONING UNCERTAINTY AND SIGNIFICANT MODEL GUIDANCE SPREAD.// NNNN NNNN