WDPN31 PGTW 132100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 29W (NAKRI) WARNING NR 
023//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 34.2N 147.7E
   INITIAL INTENSITY: 60 KTS
   GEOGRAPHIC REFERENCE: 400 NM EAST OF YOKOSUKA, JAPAN
   MOVEMENT PAST 6 HOURS: EASTWARD AT 20 KTS
   SIGNIFICANT WAVE HEIGHT: 30 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TIGHTLY
CURVED BANDING WRAPPING INTO THE WELL-DEFINED UPPER-LEVEL CIRCULATION. 
ANIMATED EIR ALSO DEPICTS EXTENSIVE COLD AIR STRATOCUMULUS AND DRY AIR 
ADVECTING OVER THE WESTERN SEMICIRCLE. A 131551Z 89GHZ AMSR2 IMAGE 
REVEALS THAT THE WESTERN FLANK OF TROPICAL STORM (TS) 29W HAS BEEN 
ERODED AND THE UPPER-LEVEL CIRCULATION CENTER (ULCC) IS BEGINNING TO 
DECOUPLE, DISPLACED APPROXIMATELY 30NM TO THE NORTHEAST. ENVIRONMENTAL 
ANALYSIS INDICATES AN UNFAVORABLE ENVIRONMENT, CHARACTERIZED BY HIGH 
(30-35 KTS) VERTICAL WIND SHEAR AND COOL (25-26 C) SEA SURFACE 
TEMPERATURES. THE INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE 
BASED ON EXTRAPOLATION FROM THE 131551Z 37GHZ ASMR2 IMAGE REVEALING 
THE WELL-DEFINED LOW-LEVEL MICROWAVE EYE. THE INITIAL INTENSITY IS 
ALSO PLACED WITH MEDIUM CONFIDENCE BASED ON THE AGENCY DVORAK FIXES 
AND THE OBJECTIVE INTENSITY ESTIMATES LISTED BELOW.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: THE NORTHERN EXTENT OF A SUBTROPICAL
RIDGE (STR) TO THE SOUTH

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.0 - 65 KTS
   RJTD: T4.0 - 65 KTS
   RCTP: T4.0 - 65 KTS
   KNES: T4.0 - 65 KTS
   CIMSS SATCON: 70 KTS AT 131622Z
   CIMSS ADT: 51 KTS AT 131800Z
   CIMSS AIDT: 63 KTS AT 131800Z
   CIMSS D-MINT: 66 KTS AT 131622Z
   CIMSS D-PRINT: 66 KTS AT 131800Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 30+ KTS
   SST: 25-26 CELSIUS
   OUTFLOW: STRONG POLEWARD

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TS 29W (NAKRI) WILL CONTINUE ITS EAST-
NORTHEASTWARD TRACK MOVEMENT, ACCELERATING ALONG THE NORTHERN
PERIPHERY OF THE STEERING STR INTO INCREASINGLY UNFAVORABLE
CONDITIONS. 29W IS FORECAST TO BEGIN EXTRATROPICAL TRANSITION (ETT)
AROUND TAU 12, THOUGH IT IS ALREADY SHOWING INTERACTION WITH THE
UPPER-LEVEL JET AND STRONG BAROCLINIC ZONE. 29W IS EXPECTED TO
RAPIDLY DETERIORATE BEGINNING AT TAU 12 AND CONTINUE TO WEAKEN 
THROUGHOUT THE REMAINDER OF THE FORECAST PERIOD DUE TO THE POOR 
ENVIRONMENTAL CONDITIONS, INCLUDING COOL SST, DRY AIR ENTRAINMENT, AND 
INTERACTION WITH THE UPPER-LEVEL WESTERLIES. THE RAPIDLY COOLING
SST INDICATE THAT 29W HAS CROSSED NORTHWARD OF THE KUROSHIO
CURRENT, WHERE THE UNFAVORABLE SST WILL HASTEN THE STORM'S TRANSITION 
INTO A COLD CORE SYSTEM. NAKRI IS FORECAST TO BECOME COMPLETELY 
EMBEDDED IN THE UPPER-LEVEL WESTERLIES AND BECOME FULLY FRONTAL NO 
LATER THAN TAU 36.

MODEL DISCUSSION: DETERMINISTIC TRACK MODELS ARE IN TIGHT AGREEMENT, 
WITH ONLY MINOR TRACK SPEED DISAGREEMENTS OCCURRING AT TAU 36. AS A 
RESULT, THE JTWC TRACK FORECAST IS PLACED WITH HIGH CONFIDENCE IN 
ALIGNMENT WITH THE MULTI-MODEL CONSENSUS AND THE BULK OF INDIVIDUAL 
MEMBERS. RELIABLE INTENSITY GUIDANCE IS LESS CERTAIN ON INTENSITY; 
HOWEVER, ALL MODELS ARE IN GOOD AGREEMENT THAT 29W WILL STEADILY 
WEAKEN BEGINNING AT TAU 12. THEREFORE, THE JTWC INTENSITY FORECAST IS 
PLACED WITH HIGH CONFIDENCE.

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