WDPN31 PGTW 122100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 29W (NAKRI) WARNING NR 019//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 32.2N 138.3E
   INITIAL INTENSITY: 70 KTS
   GEOGRAPHIC REFERENCE: 188 NM SOUTH OF CAMP FUJI
   MOVEMENT PAST 6 HOURS: EAST-NORTHEASTWARD AT 16 KTS
   SIGNIFICANT WAVE HEIGHT: 28 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS AN
ASYMMETRIC DEEP CONVECTIVE STRUCTURE TILTED TO THE EAST OF THE
LOW-LEVEL CIRCULATION CENTER (LLCC) DUE TO MODERATE WESTERLY
VERTICAL WIND SHEAR. WATER VAPOR IMAGERY REVEALS THAT OUTFLOW IS
ENHANCED STRONGLY POLEWARD AND QUICKLY WHISKED AWAY EASTWARD INTO
THE ZONAL FLOW OF THE SUBTROPICAL JET TO THE NORTH. THE INITIAL
POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON A 121838Z GPM GMI
37GHZ MICROWAVE IMAGE REVEALING A MICROWAVE EYE FEATURE, WHILE THE
89GHZ IMAGE DEPICTS A POORLY ORGANIZED STRUCTURE. THE INITIAL
INTENSITY OF 70 KTS IS ASSESSED WITH MEDIUM CONFIDENCE DUE TO A
LAPSE OF WIND SPEED DATA AND IS BASED ON THE AGENCY AND OBJECTIVE
FIXES LISTED BELOW.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: A SUBTROPICAL RIDGE TO THE SOUTHEAST
ENHANCED BY THE FLOW OF THE SUBTROPICAL JET TO THE NORTH.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.0 - 65 KTS
   RJTD: T4.5 - 77 KTS
   RCTP: T4.0 - 65 KTS
   CIMSS SATCON: 73 KTS AT 121641Z
   CIMSS ADT: 74 KTS AT 121730Z
   CIMSS AIDT: 69 KTS AT 121730Z
   CIMSS D-MINT: 66 KTS AT 121641Z
   CIMSS D-PRINT: 70 KTS AT 121800Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 15-20 KTS
   SST: 26-27 CELSIUS
   OUTFLOW: STRONG POLEWARD

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TYPHOON (TY) 29W WILL CONTINUE TO TRACK ON AN
EAST-NORTHEASTWARD TRACK FOR THE REMAINDER OF THE FORECAST PERIOD,
INCREASING TRACK SPEED FROM 18KTS AT TAU 12 TO 28KT KTS BY TAU 72
AS THE SYSTEM BECOMES EMBEDDED WITHIN THE SUBTROPICAL JET TO THE
NORTH. SLIGHT INTENSIFICATION IS EXPECTED TO A PEAK OF 75KTS OVER
THE NEXT 12 HOURS WHILE THE SYSTEM REMAINS IN A FAVORABLE
ENVIRONMENT WITH WARM SEA SURFACE TEMPERATURES, MODERATE VERTICAL
WIND SHEAR, AND POLEWARD OUTFLOW. TY 29W IS ANTICIPATED TO EXIT THE
WARM WATERS OF THE KUROSHIO CURRENT BY TAU 36, REMOVING THE HEAT
SOURCE FROM THE SYSTEM. ADDITIONALLY, VERTICAL WIND SHEAR WILL HAVE
BECOME UNFAVORABLY HIGH ABOVE 20KTS DURING THAT SAME PERIOD, AND
WILL CONTINUE TO RISE AS THE SYSTEM BECOMES FURTHER EMBEDDED WITHIN
THE SUBTROPICAL JET. EXTRATROPICAL TRANSITION IS EXPECTED TO
COMMENCE BY TAU 48, AND COMPLETE BY TAU 72 WHEN THE SYSTEM HAS
WEAKENED TO 40KTS.

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE IS IN GOOD AGREEMENT
THAT TY 29W WILL REMAIN ON A NORTHEASTWARD OR AN EAST-NORTHEASTWARD
TRACK FOR THE REMAINDER OF THE FORECAST PERIOD. THE CROSS-TRACK
SPREAD IS TIGHTLY PACKED FOR MUCH OF THE FORECAST, WITH THE
EXCEPTION OF NAVGEM AND HAS A CROSS-TRACK SPREAD OF 70NM. THE
INTENSITY GUIDANCE IS IN GOOD AGREEMENT THAT TY 29W WILL SLIGHTLY
INTENSIFY OVER THE NEXT 12 HOURS TO A PEAK OF 75-80KTS, FOLLOWED BY
A WEAKENING PERIOD AS THE SYSTEM IS FACED WITH LESS FAVORABLE
CONDITION.

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