WDPN31 PGTW 080300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 07W (OMAIS) WARNING NR
15//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 07W (OMAIS), LOCATED APPROXIMATELY 251 NM
EAST-SOUTHEAST OF YOKOSUKA, JAPAN, HAS TRACKED NORTH-NORTHWESTWARD
AT 14 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL
SATELLITE IMAGERY DEPICTS MULTIPLE VORTICES ORBITING A VERY ILL-
DEFINED LOW LEVEL CIRCULATION CENTER (LLCC), SURROUNDED BY A BROAD
AREA OF INCREASINGLY SHALLOW CONVECTION. TIGHTLY CURVED BANDING CAN
STILL BE OBSERVED IN A 072105Z CORIOLIS 37 GHZ PASS, ALTHOUGH THE
LLCC REMAINS ILL DEFINED EVEN IN THE MICROWAVE IMAGERY. THE INITIAL
POSITION IS BASED ON FIXES FROM PGTW AND RJTD, HOWEVER, THERE IS
POOR CONFIDENCE DUE TO THE LACK OF A CLEAR LLCC. THE INITIAL
INTENSITY HAS BEEN HELD AT 50 KNOTS BASED ON AN EARLIER ASCAT PASS,
AS DVORAK ESTIMATES ARE NOT REPRESENTATIVE FOR THIS VERY LARGE
SYSTEM. THE ENVIRONMENT IS NOT SUPPORTIVE FOR FURTHER DEVELOPMENT,
WITH DRY AIR ENTRAINMENT AND MINIMALLY SUPPORTIVE SEA SURFACE
TEMPERATURES (SSTS). 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 IS EXPECTED TO ROUND THE STR AND RECURVE TO THE
NORTHEAST OVER THE NEXT 12-24 HOURS. PEAK WINDS WILL DECAY SLOWLY
DUE TO THE LARGE SCALE OF THE CIRCULATION, COMBINED WITH CONTINUED
GOOD OUTFLOW. THE SYSTEM WILL BEGIN EXTRATROPICAL TRANSITION (ETT)
AROUND TAU 24, AS THE NORTHERN PERIPHERY BEGINS TO INTERACT WITH AN
APPROACHING UPPER LEVEL TROUGH. TS 07W WILL COMPLETE ETT BY THE END
OF THE FORECAST PERIOD AS IT EMBEDS IN THE MID-LATITUDE WESTERLY
FLOW AND ACCERLERATES TO THE NORTHEAST AS A GALE FORCE LOW. DYNAMIC
MODEL GUIDANCE REMAINS IN VERY TIGHT AGREEMENT, LENDING HIGH
CONFIDENCE TO THE JTWC TRACK FORECAST./=