WDPN32 PGTW 011500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 19W (JEBI) WARNING NR 
021//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 37.2N 143.6E
   INITIAL INTENSITY: 50 KTS
   GEOGRAPHIC REFERENCE: 179 NM EAST-NORTHEAST OF NARITA AIRPORT
   MOVEMENT PAST 6 HOURS: NORTH-NORTHEASTWARD AT 26 KTS
   SIGNIFICANT WAVE HEIGHT: 27 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
COLLAPSING CONVECTIVE STRUCTURE WITH WARMING CLOUD TOPS OBSCURING
THE LOW-LEVEL CIRCULATION CENTER (LLCC). A 011111Z METOP-B AMSU-B
89GHZ IMAGE HIGHLIGHTS THE DEGRADING STATE OF TROPICAL STORM (TS)
19W AS IT SCREAMS NORTHEASTWARD. THE WARMING CLOUD TOPS CAN BE
ATTRIBUTED TO THE COOL SEA SURFACE TEMPERATURES BELOW 26C WHICH NO
LONGER FUELS THE SYSTEM FAVORABLY FOR INTENSIFICATION. A STRONG
UPPER-LEVEL JET EXTENDING OVER THE SEA OF JAPAN ERODES THE
NORTHWESTERN QUADRANT OF THE SYSTEM. THE INITIAL POSITION IS PLACED
WITH MEDIUM CONFIDENCE BASED ON THE AFOREMENTIONED ANIMATED EIR AND
EXTRAPOLATION FROM THE AMSU-B IMAGE. THE INITIAL INTENSITY OF 50
KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE DEGRADING
NATURE OF 19W ACCOMPANYING THE AGENCY AND OBJECTIVE FIXES BELOW.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: A SUBTROPICAL RIDGE (STR) TO THE
SOUTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   RJTD: T4.0 - 65 KTS
   RCTP: T4.0 - 65 KTS
   KNES: T4.5 - 77 KTS
   CIMSS ADT: 55 KTS AT 011130Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 10-15 KTS
   SST: 25-26 CELSIUS
   OUTFLOW: MODERATE EASTWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: MEDIUM
   INITIAL WIND RADII: LOW

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: TS 19W WILL CONTINUE TO TRACK EASTWARD FOR THE
NEXT 24 HOURS GUIDED BY THE STR TO THE SOUTHEAST AND AT AN ENHANCED
SPEED AS THE SYSTEM BECOMES EMBEDDED WITHIN THE JET TO THE NORTH.
WHILE IN THE CURRENT ENVIRONMENT OF COOL AND UNFAVORABLE SEA
SURFACE TEMPERATURES, TS 19W WILL CONTINUE TO UNDERGO EXTRATROPICAL
TRANSITION FOR THE NEXT 12 HOURS AND BECOME FULLY EXTRATROPICAL BY
TAU 24. IN THE MEANTIME, THE INTENSITY WILL DECLINE DUE TO THE COOL
WATERS ALONGSIDE HIGH SHEAR ABOVE 25-30KTS THAT IS INTRODUCED BY
THE JET INTERACTION AT TAU 12. THE SYSTEM WILL CONTINUE TO WEAKEN
TO 25KTS BY TAU 24.

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE IS IN GOOD AGREEMENT
THAT THE SYSTEM WILL REMAIN UNDER THE STEERING INFLUENCE OF THE
SOUTHERN STR, BRINGING TS 19W NORTHEASTWARD THROUGH THE END OF THE
FORECAST. THE HIGH CONFIDENCE IN THE JTWC FORECAST IS AFFIRMED BY
THE LOW CROSS-TRACK SPREAD OF 175NM BY TAU 24. THE JTWC INTENSITY
GUIDANCE WAS ONLY REPRESENTED BY TWO MEMBERS, GFS AND HAFS-A. THESE
TWO MEMBERS HAD A SPREAD OF 30KTS AT TAU 12. HOWEVER, THE JTWC 
INTENSITY
GUIDANCE KEPT TO THE LOWER INTENSITY OF HAFS-A BASED ON THE CURRENT
UNFAVORABLE ENVIRONMENT. 

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: HIGH
   INTENSITY 0 - 72 HR: MEDIUM//
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