MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 15W (MOLAVE) WARNING NR 09// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM (TS) 15W (MOLAVE), LOCATED APPROXIMATELY 489 NM SOUTH OF YOKOSUKA, JAPAN, HAS TRACKED NORTHWESTWARD AT 08 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY SHOWS A PARTIALLY-EXPOSED LOW LEVEL CIRCULATION WITH THE BULK OF THE DEEP CONVECTION NOW SHEARED TO THE SOUTH. THIS IS CAUSED BY A TUTT CELL ALOFT THAT HAS REMAINED IN PLACE AND IS NOW DIRECTLY OVER TS 15W AND CAUSING SUBSIDENCE ALONG THE NORTHERN TO EASTERN QUADRANTS. THE INITIAL POSITION IS BASED ON THE MSI LOOP AND FROM A LLCC FEATURE IN THE 082217Z SSMIS MICROWAVE PASS. THE INITIAL INTENSITY OF 35 KNOTS IS BASED ON AN OVERALL ASSESSMENT OF DVORAK INTENSITY ESTIMATES FROM PGTW AND RJTD AND REFLECTS THE SUSTAINED CONVECTIVE SIGNATURE OF THE SYSTEM. UPPER-LEVEL ANALYSIS INDICATES THE SYSTEM REMAINS IN A MARGINAL ENVIRONMENT WITH MODERATE VWS AND SUPPRESSED OUTFLOW. THE CYCLONE IS CURRENTLY TRACKING ALONG THE SOUTHWESTERN PERIPHERY OF AN EXTENSION OF A STR TO THE EAST. 3. FORECAST REASONING. A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TS 15W HAS BEGUN TO ROUND THE RIDGE AXIS AND TRACK MORE POLEWARD. AFTER TAU 24, THE SYSTEM IS EXPECTED TO ACCELERATE NORTHEASTWARD ON THE POLEWARD SIDE OF THE STR. MARGINAL CONDITIONS WILL PERSIST, ALLOWING ONLY MINIMAL INTENSIFICATION. BEYOND TAU 24, VWS IS EXPECTED TO DECREASE AND POLEWARD OUTFLOW WILL INCREASE, SUPPORTING MODERATE INTENSIFICATION TO A PEAK OF 55 KNOTS BY TAU 48. AFTERWARDS, TS 15W IS FORECAST TO ACCELERATE AND BEGIN EXTRA-TROPICAL TRANSITION (ETT) AS IT INTERACTS WITH THE MID-LATITUDE WESTERLIES. C. IN THE EXTENDED PERIOD, TS MOLAVE WILL ERODE QUICKLY DUE TO INCREASED VWS AND INTERACTION WITH THE COLD BAROCLINIC ZONE. TS 15W SHOULD COMPLETE ETT BY THE END OF THE FORECAST PERIOD AS IT GAINS FRONTAL CHARACTERISTICS. DYNAMIC MODEL GUIDANCE REMAINS IN A TIGHT AGREEMENT, LENDING HIGH CONFIDENCE IN THE JTWC TRACK FORECAST.// NNNN NNNN