WDPN31 PGTW 081500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 07W (OMAIS) WARNING NR
17//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM 07W (OMAIS), LOCATED APPROXIMATELY 230 NM EAST OF
YOKOSUKA, JAPAN, HAS TRACKED NORTHWARD AT 10 KNOTS OVER THE PAST SIX
HOURS. ANIMATED INFRARED SATELLITE IMAGERY DEPICTS CONTINUED
ELONGATION OF THE CONVECTIVE STRUCTURE DUE TO INTERACTION WITH THE
MID-LATITUDE WESTERLY FLOW. A 081201Z GPM 89GHZ MICROWAVE IMAGE
SHOWS A NORTH-SOUTH ELONGATED LOW LEVEL CIRCULATION CENTER WHICH
PROVIDES FAIR CONFIDENCE IN THE CURRENT POSITION. THE AMSU
TEMPERATURE ANOMALY CROSS SECTION CONTINUES TO SHOW A WARM CORE
DEVELOPING AT THE SURFACE. THE INITIAL INTENSITY HAS BEEN DECREASED
TO 40 KNOTS BASED ON A 081049Z ASCAT PASS SHOWING A LARGE FIELD OF
40 KNOT WINDS LOCATED WITHIN THE EASTERN SEMI-CIRCLE. THE UPPER
LEVEL ENVIRONMENT CONTINUES TO DETERIORATE DUE TO INCREASED
INTERACTION WITH THE BAROCLINIC ZONE. SEA SURFACE TEMPERATURES ARE
BELOW 26 CELSIUS. TS 07W IS TRACKING POLEWARD ALONG THE WESTERN
PERIPHERY OF A DEEP-LAYERED SUB-TROPICAL RIDGE (STR) POSITIONED TO
THE EAST.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. TS 07W WILL BEGIN TO ACCELERATE NORTHEASTWARD ALONG THE
LEADING EDGE OF THE APPROACHING MID-LATITUDE TROUGH. THE CYCLONE
WILL CONTINUE TO TRANSITION TO AN EXTRATROPICAL SYSTEM AS IT EMBEDS
DEEPER INTO THE BAROCLINIC ZONE. THE MAXIMUM WINDS WILL SLOWLY
DECREASE; HOWEVER, AS THE SYSTEM GAINS UPPER LEVEL SUPPORT IT WILL
MAINTAIN ITS STRONG WIND FIELD. TS OMAIS WILL COMPLETE EXTRATROPICAL
TRANSITION BY THE END OF THE FORECAST PERIOD AS A STRONG COLD CORE
LOW. DYNAMIC MODEL GUIDANCE REMAINS IN VERY TIGHT AGREEMENT, LENDING
HIGH CONFIDENCE TO THE JTWC TRACK FORECAST.//