WDPN31 PGTW 130900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 29W (NAKRI) WARNING NR 021//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 33.8N 142.8E
   INITIAL INTENSITY: 65 KTS
   GEOGRAPHIC REFERENCE: 164 NM SOUTHEAST OF NARITA AIRPORT
   MOVEMENT PAST 6 HOURS: EAST-NORTHEASTWARD AT 20 KTS
   SIGNIFICANT WAVE HEIGHT: 30 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TYPHOON
(TY) 29W (NAKRI) AS A WEAKENING SYSTEM WITH THE CIRCULATION
CONTINUING TO TRACK NORTHEAST, STEERED BY AN ELONGATED SUBTROPICAL 
RIDGE (STR) CENTERED TO THE EAST. CONVECTION HAS BECOME RELEGATED TO 
THE NORTHEASTERN QUADRANT OF THE SYSTEM, WHILE THE CLOUD TOPS 
TEMPERATURES HAVE WARMED. CURRENT ENVIRONMENTAL CONDITIONS CONTINUE 
TO BECOME MORE UNFAVORABLE FOR TY NAKRI WITH COOLING SEA SURFACE 
TEMPERATURES (26 C TO 27 C), HIGH VERTICAL WIND SHEAR (25-30 KTS), 
AND A SIGNIFICANT AMOUNT OF DRY AIR WRAPPING INTO THE CORE OF THE 
VORTEX. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON 
A 130600Z HM9 IR IMAGERY. THE INITIAL INTENSITY IS ALSO PLACED WITH 
HIGH CONFIDENCE BASED ON THE OBJECTIVE ESTIMATES LISTED BELOW, AS 
WELL AS A WEAKENING TREND INDICATED BY THE AGENCY DVORAK ESTIMATES.

INITIAL WIND RADII BASIS: 130346Z AMSR2 WIND SPEED DATA 

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE TO THE EAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   RJTD: T4.5 - 77 KTS
   RCTP: T4.5 - 77 KTS
   KNES: T4.5 - 77 KTS
   CIMSS SATCON: 66 KTS AT 130400Z
   CIMSS ADT: 53 KTS AT 130530Z
   CIMSS AIDT: 64 KTS AT 130530Z
   CIMSS D-MINT: 65 KTS AT 130617Z
   CIMSS D-PRINT: 69 KTS AT 130600Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 25-30 KTS
   SST: 26-27 CELSIUS
   OUTFLOW: MODERATE POLEWARD AND EQUATORWARD

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TY 29W WILL CONTINUE ON AN EAST-NORTHEASTWARD
TRACK FOR THE REMAINDER OF THE FORECAST PERIOD. ENVIRONMENTAL
CONDITIONS ARE FORECAST TO BECOME PROGRESSIVELY MORE UNFAVORABLE
WITH THE CIRCULATION TREKKING INTO A HIGH WIND SHEAR (30-40 KTS)
AREA AND OVER COOLING SEA SURFACE TEMPERATURES (24 C TO 25 C),
WHILE CONTINUING TO INGEST DRY AIR INTO THE CORE OF THE SYSTEM.
EXTRATROPICAL TRANSITION (ETT) WILL COMMENCE AROUND TAU 24, WHICH
WILL RESULT IN THE SYSTEM BECOMING VERTICALLY TILTED WITH HEIGHT,
COINCIDING WITH FRONTOGENESIS AND DEVELOPMENT OF A COLD CORE. TY
NAKRI WILL COMPLETE ETT BY TAU 48 AT AN INTENSITY OF AROUND 40 KTS.

MODEL DISCUSSION: MODELS ARE IN TIGHT AGREEMENT WITH A CROSS-TRACK
SPREAD UNDER 40 NM UNTIL AROUND TAU 36. THE HIGH CONFIDENCE JTWC
TRACK IS PLACED CLOSE TO THE MULTI-MODEL CONSENSUS. INTENSITY
GUIDANCE HAS ALSO COME INTO BETTER AGREEMENT WITH MAJORITY OF THE
MODELS WITHIN A 5-10 KT SPREAD. PEAK INTENSITY FOR THE REMAINDER OF
THE FORECAST IS 65 KTS WITH A STEEP WEAKENING TREND EXPECTED AFTER
TAU 24, AS THE SYSTEM UNDERGOES EXTRATROPICAL TRANSITION (ETT). THE
FORECAST INTENSITY IS PLACED WITH HIGH CONFIDENCE AND THE JTWC
OFFICIAL FORECAST LIES BETWEEN THE MULTI-MODEL CONSENSUS AND THE
HAFS-A MODEL, WHICH HAS PROVED TO BE AN ACCURATE ESTIMATE
THROUGHOUT THE FORECAST. 

FORECAST CONFIDENCE:
   TRACK 00-72 HR: HIGH
   INTENSITY 00-72 HR: HIGH//
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