WDPN31 PGTW 272100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 20W (MINDULLE) WARNING NR 022//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 20.5N 136.3E
   INITIAL INTENSITY: 90 KTS
   GEOGRAPHIC REFERENCE: 378 NM SOUTHWEST OF IWO TO
   MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 04 KTS
   SIGNIFICANT WAVE HEIGHT: 42 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
CONSTRICTING, BUT FRAGMENTED EYEWALL WITHIN TY 20W AS IT COMPLETES
ITS EYEWALL REPLACEMENT CYCLE. ANIMATED WATER VAPOR IMAGERY SHOWS
CONVECTION STRENGTHENING AS THE SYSTEM MOVES AWAY FROM THE COLD
POOL OF UPWELLED WATER CREATED BY THE SLOW TRACK MOVEMENT. THE
INITIAL INTENSITY IS ASSESSED AT 90 KTS BASED ON THE PGTW CURRENT
INTENSITY ESTIMATE OF 5.0(90 KTS), AND IS HEDGED SLIGHTLY LOWER
THAN ADT (99 KTS). THE INITIAL POSITION IS BASED ON THE LARGE EYE
FEATURE IN EIR AND IS SUPPORTED BY MULTIPLE AGENCY FIX POSITIONS.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: DEVELOPING SUBTROPICAL RIDGE TO THE
SOUTHEAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.0 - 90 KTS
   RJTD: T6.0 - 115 KTS
   KNES: T5.0 - 90 KTS
   CIMSS SATCON: 102 KTS AT 271646Z
   CIMSS ADT: 99 KTS AT 271740Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 0-5 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG RADIAL

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   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: TY 20W WILL BEGIN A NORTHWARD TRACK AND THEN
TURN NORTHEASTWARD AROUND TAU 48 AS THE SUBTROPICAL RIDGE BUILDING
TO THE SOUTHEAST TAKES A MORE NORTHEAST-SOUTHWEST ORIENTATION. AFTER 
TAU 48, THE SYSTEM WILL ACCELERATE ON ITS NORTHEASTWARD TRACK AS A
MID-LATITUDE TROUGH APPROACHES FROM THE WEST. AS THE EYEWALL 
CONTINUES TO CONSTRICT AND THE SYSTEM MOVES AWAY FROM THE COLD POOL 
OF UPWELLED WATER, TY 20W WILL INCREASE IN INTENSITY REACHING A PEAK 
OF 110 KTS AROUND TAU 48. AFTERWARDS, INCREASING VERTICAL WIND SHEAR 
AND A DRY AIR MASS TO THE WEST WILL BEGIN TO WEAKEN THE SYSTEM, 
REACHING 85 KTS BY TAU 96. AT THIS POINT, TY 20W WILL BEGIN TO 
INTERACT WITH THE BAROCLINIC ZONE AND BEGIN EXTRATROPICAL TRANSITION 
(ETT) WHICH IT WILL COMPLETE NO LATER THAN TAU 120.

MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE IS IN VERY GOOD
AGREEMENT WITH ONLY A 50 NM CROSS-TRACK SPREAD AT TAU 48, AND ONLY
INCREASING TO 160 NM AT TAU 120. HOWEVER, THE ALONG-TRACK SPREAD
DOES BEGIN TO INCREASE AT TAU 96 AS MODELS BEGIN TO DISAGREE ON
TRACK SPEED AS THE SYSTEM UNDERGOES ETT. INTENSITY GUIDANCE IS ALSO
IN GOOD AGREEMENT, WITH ALL MODELS SHOWING AN INCREASE IN INTENSITY 
PEAKING AROUND TAU 48 FOLLOWED BY A DECREASING TREND FOR THE 
REMAINDER OF THE FORECAST. THE FORECAST INTENSITY IS THEREFORE 
PLACED CLOSE TO CONSENSUS.

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: HIGH
   TRACK 72-120 HR: HIGH
   INTENSITY 0 - 72 HR: MEDIUM
   INTENSITY 72-120 HR: MEDIUM//
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