WDPN31 PGTW 110900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 29W (NAKRI) WARNING NR 
013//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 27.7N 131.0E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 185 NM EAST-NORTHEAST OF KADENA AB
   MOVEMENT PAST 6 HOURS: NORTHEASTWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 16 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL
STORM (TS) 29W (NAKRI) WITH A PARTIALLY EXPOSED LOW-LEVEL
CIRCULATION (LLCC). ASSOCIATED CONVECTION CONTINUES TO FLARE UP
PRIMARILY IN THE SOUTHWEST QUADRANT, ALTHOUGH A SMALL POCKET OF
CONVECTIVE ACTIVITY IN THE NORTHEAST QUADRANT HAS KICKED UP AGAIN.
THOUGH VERTICAL WIND SHEAR REMAINS FAVORABLE (5-10 KTS), THE SMALL
SYSTEM IS STRUGGLING TO MAINTAIN ORGANIZATION. THE CLOUD TOPS HAVE
BEEN ON A WARMING TREND (-65 C TO -69 C). ADDITIONAL ENVIRONMENTAL 
ANALYSIS REVEALS A CONTINUOUSLY MOIST VORTEX CORE, DESPITE DRY AIR 
IMPINGING ON THE CIRCULATION FROM WEST AND EAST. THE INITIAL POSITION 
IS PLACED WITH HIGH CONFIDENCE BASED ON THE AFOREMENTIONED PARTIALLY
EXPOSED LLCC IDENTIFIED IN EIR AND CLOUD BANDS IDENTIFIABLE ON THE
ANIMATED DOPPLER RADAR LOOP. THE INITIAL INTENSITY OF 35 KTS IS
ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE AGENCY AND OBJECTIVE
FIXES LISTED BELOW.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) TO THE EAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   RJTD: T2.5 - 35 KTS
   RCTP: T3.0 - 45 KTS
   KNES: T2.5 - 35 KTS
   CIMSS SATCON: 41 KTS AT 110436Z
   CIMSS ADT: 32 KTS AT 110530Z
   CIMSS AIDT: 36 KTS AT 110530Z
   CIMSS D-MINT: 41 KTS AT 110436Z
   CIMSS D-PRINT: 38 KTS AT 110600Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG POLEWARD AND EQUATORWARD

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 NAKRI HAS BEGUN ITS NORTHEASTWARD TRACK
HAVING COME BACK UNDER THE INFLUENCE OF A STR TO THE EAST AS ITS
PRIMARY STEERING MECHANISM. THE SYSTEM WILL CONTINUE NORTHEAST 
THROUGH TAU 72, WHILE ENCOUNTERING INCREASINGLY WARM SEA TEMPERATURES 
(29-30 C) ALONG THE WAY. THIS WILL ALLOW FOR A PERIOD OF RE-
STRENGTHENING THROUGH TAU 48, BEFORE INCREASING VERTICAL WIND SHEAR, 
COOLER SEA TEMPERATURES (26-27 C), AND THE INFLUENCE OF THE JET HELP 
THE SYSTEM ALONG ITS EXTRATROPICAL TRANSITION (ETT). TS NAKRI IS
FORECAST TO COMPLETE THE ETT BY TAU 96. 

MODEL DISCUSSION: DETERMINISTIC MODEL TRACK GUIDANCE IS IN GOOD
AGREEMENT, AS WITNESSED BY A CROSS-TRACK SPREAD OF UNDER 30 NM UNTIL
TAU 36. AFTERWARDS, GUIDANCE IS ONLY SLIGHTLY MORE UNCERTAIN WITH
HOW FAR NORTH THE SYSTEM WILL TRAVEL, AS IT COMPLETES THE ETT. THE 
JTWC OFFICIAL FORECAST IS PLACED CLOSE TO THE CONSENSUS GUIDANCE 
THROUGHOUT THE FORECAST PERIOD. INTENSITY ASSESSMENT IS IN FAIR 
AGREEMENT, PARTICULARLY IN REGARD TO A PERIOD OF INTENSIFICATION 
THROUGH TAUS 48-72, FOLLOWED BY A WEAKENING TREND. HOWEVER, 
UNCERTAINTY ASSOCIATED WITH THE TIMELINESS DECREASES FORECAST 
CONFIDENCE. ADDITIONALLY, PEAK INTENSITY GUIDANCE SPREAD IS CURRENTLY 
AT 40 KTS, WITH THE MOST CONSERVATIVE ASSESSMENT FROM STATISTICAL-
DYNAMICAL MODELS, WHILE MOST AGGRESSIVE COAMPS-TS AND DETERMINISTIC 
GFS REACH 90-95 KTS. THE JTWC FORECAST REFLECTS AN INTENSITY MAXIMUM 
IN LINE WITH HAFS-A GUIDANCE, HOWEVER IT IS CLOSER TO THE MULTI-MODEL 
CONSENSUS IN REGARD TO THE TIMELINE OF INTENSIFICATION. THEREFORE, 
THE FORECASTED INTENSITY IS PLACED WITH MEDIUM CONFIDENCE THROUGHOUT 
THE FORECAST PERIOD.

FORECAST CONFIDENCE:
   TRACK 00-72 HR: HIGH
   TRACK 72-120 HR: MEDIUM
   INTENSITY 00-72 HR: MEDIUM
   INTENSITY 72-120 HR: MEDIUM//
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