Tropical Storm MOLAVE Advisory dom, 09-08

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.//
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