WDPN31 PGTW 091500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 08W (NEOGURI) WARNING 
NR 27//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 08W (NEOGURI), LOCATED APPROXIMATELY 124 NM
SOUTHWEST OF SASEBO, JAPAN, HAS TRACKED EAST-NORTHEASTWARD AT 09
KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE 
IMAGERY (EIR) SHOWS TS 08W HAS FURTHER DEVOLVED INTO AN ELONGATED 
LOW LEVEL CIRCULATION CENTER (LLCC) WITH ISOLATED DEEP CONVECTION 
ALONG THE SOUTHERN PERIPHERY. A 091220Z AMSU-B MICROWAVE IMAGE SHOWS 
LIMITED DEEP CONVECTION IN THE SOUTHERN SEMI-CIRCLE AND SHALLOW 
CONVECTION ELSEWHERE AS THE STRUCTURE OF THE SYSTEM CONTINUES TO 
WANE. THERE IS NOW LOW CONFIDENCE IN THE INITIAL POSITION DUE TO THE 
ELONGATED NATURE OF THE LLCC SEEN IN THE EIR LOOP AS AGENCY 
POSITION FIXES ARE CONTINUING TO SPREAD. THE INITIAL INTENSITY HAS 
BEEN DECREASED TO 60 KNOTS BASED UPON THE DECREASING STRUCTURE AND 
IS BETWEEN DVORAK FINAL-T AND CURRENT INTENSITY ESTIMATES THAT RANGE 
FROM 45 TO 65 KNOTS. UPPER LEVEL ANALYSIS REVEALS A DECREASING 
ENVIRONMENT AS MODERATE TO STRONG (20 TO 30 KNOTS) NORTHERLY 
VERTICAL WIND SHEAR (VWS) CONTINUES TO HAMPER POLEWARD OUTFLOW. TS 
NEOGURI HAS MADE A TURN EAST-NORTHEAST ALONG THE PERIPHERY OF THE 
SUBTROPICAL RIDGE (STR) THAT IS MODIFYING IN RESPONSE TO AN 
APPROACHING MID-LATITUDE TROUGH LOCATED OVER NORTHEASTERN CHINA.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE 
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TS 08W IS FORECAST TO CONTINUE EAST-NORTHEAST, MAKING LANDFALL 
ACROSS CENTRAL KYUSHU AROUND 20Z ON THE 9TH. THE WEAKENING TREND IS 
EXPECTED TO CONTINUE AS SEA SURFACE TEMPERATURES DECREASE, VWS 
FURTHER INCREASES, AND LOW LEVEL INFLOW IS DISRUPTED AS THE SYSTEM 
APPROACHES THE MOUNTAINOUS TERRAIN OF JAPAN. AFTER LANDFALL, THE 
SYSTEM WILL BEGIN TO INCREASE IN TRACK SPEED AND CONTINUE TO DEVOLVE 
AS THE SYSTEM BECOMES EMBEDDED IN THE MID-LATITUDE WESTERLIES AND 
EXTRA-TROPICAL TRANSITION BEGINS. TS NEOGURI WILL ACCELERATE TO THE 
NORTHEAST UNDER THE COMBINED INFLUENCE OF THE STR AND THE 
AFOREMENTIONED DEEP MID-LATITUDE TROUGH AS THE TROUGH MOVES OVER 
NORTHERN JAPAN. THE SYSTEM IS EXPECTED TO BE FULLY EXTRA-TROPICAL 
BETWEEN TAU 48 WITH POSSIBLE EARLIER TRANSITION. THE AVAILABLE 
DYNAMIC MODEL GUIDANCE REMAINS IN TIGHT AGREEMENT, LENDING TO HIGH 
CONFIDENCE IN THE JTWC TRACK FORECAST.//
NNNN