WDPN31 PGTW 281500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 20W (MINDULLE) WARNING NR 025//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 22.0N 135.5E
   INITIAL INTENSITY: 100 KTS
   GEOGRAPHIC REFERENCE: 361 NM WEST-SOUTHWEST OF IWO TO
   MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 04 KTS
   SIGNIFICANT WAVE HEIGHT: 45 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
WHILE TY20W HAS MOVED INTO A MORE FAVORABLE ENVIRONMENT, ANIMATED
ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS THAT IT CONTINUES
TO STRUGGLE TO REINTENSIFY. OVER THE PAST SIX HOURS, THE EYE HAS
STEADILY SHRUNK, BUT IT REMAINS CLOUD COVERED AND RAGGED, BUT HAS
YET TO ESTABLISH AN UNBROKEN EYEWALL. LATER FRAMES ARE SHOWING COLD
CONVECTIVE BANDS BEGINNING TO SWING AROUND FROM THE SOUTH AND ARE
PROVIDING SOME HINTS THAT A SOLID EYEWALL MAY BE ABOUT TO FINALLY
FORM. THE INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE, BASED
ON THE RAGGED, APPROXIMATELY 20 NM WIDE EYE. THE INITIAL INTENSITY
IS ASSESSED AT 100 KNOTS WITH MEDIUM CONFIDENCE, ROUGHLY IN THE
MEAN OF AGENCY INTENSITY ESTIMATES AND BELOW THE ADT AND SATCON
ESTIMATES. AS PREVIOUSLY MENTIONED, THE ENVIRONMENT HAS IMPROVED
WITH WARM (30C) SSTS, LOW SHEAR AND GOOD RADIAL OUTFLOW. THE RADIAL
OUTFLOW EXTENDS ABOUT 400 NM WEST FROM THE CENTER BEFORE TURNING
SHARPLY EASTWARD, WITH BULK OF THE OUTFLOW REMAINING BELOW THE 30TH
LATITUDE BEFORE TURNING EQUATORWARD WELL TO THE NORTHEAST OF THE
CENTER. THE SYSTEM HAS LEFT THE COLD POOL IN ITS WAKE AND WHILE
SSTS ARE WARM ON THE ROAD AHEAD, OHC REMAINS RELATIVELY LOW WITH
VALUES BETWEEN 50-75 KILOJOULES.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: NORTHWEST PERIPHERY OF BUILDING
SUBTROPICAL RIDGE (STR) CENTERED OVER THE MARIANAS, WITH AN
EXTENSION BUILDING TO THE NORTH. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.0 - 90 KTS
   RJTD: T6.0 - 115 KTS
   RCTP: T5.5 - 102 KTS
   KNES: T5.0 - 90 KTS
   CIMSS SATCON: 103 KTS AT 281033Z
   CIMSS ADT: 107 KTS AT 281140Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 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 HAS SLOWED A BIT OVER THE PAST SIX
HOURS, WITH FORWARD MOTION DOWN TO ABOUT 04 KNOTS. GLOBAL MODEL
FIELDS INDICATE THAT WHILE THE UPPER PORTIONS OF RIDGE THAT LIES TO
THE NORTH HAS ERODED AND RETREATED WEST, AT THE MID-LEVELS THE
RIDGE REMAINS IN PLACE. THIS IS LIKELY WHAT HAS CAUSED THE SYSTEM
TO TAP THE BRAKES A BIT. HOWEVER, THIS SLOW DOWN IS EXPECTED TO BE
SHORT-LIVED, AS THE RIDGE TO THE NORTH IS FORECAST TO COMPLETELY 
ERODE IN THE NEXT 12 TO 18 HOURS. THROUGH TAU 12 THE SYSTEM WILL MOVE
NORTHWARD AT ABOUT 05 KNOTS, THEN START TO PICK UP SPEED THEREAFTER
AS THE RIDGE TO THE NORTH GETS KNOCKED BACK BY AN APPROACHING
TROUGH. TY 20W WILL TURN NORTHEASTWARD AFTER TAU 24 AND PUT THE
PEDAL DOWN, MOVING RAPIDLY NORTHEAST ALONG THE STRONG GRADIENT
BETWEEN THE TROUGH TO THE WEST AND THE RIDGE TO THE EAST. A SURFACE
LOW CURRENTLY IN THE NORTHERN YELLOW SEA IS EXPECTED TO RAPIDLY
MOVE NORTHEASTWARD OVER THE NEXT 48 HOURS, DRAGGING ITS ASSOCIATED
COLD FRONT ACROSS THE SEA OF JAPAN AND BY TAU 60, WILL STRADDLE THE
ISLAND OF HONSHU. AS TY 20W APPROACHES FROM THE SOUTHWEST, IT WILL
BEGIN TO INTERACT WITH THIS BAROCLINIC ZONE AND BEGIN
EXTRA-TROPICAL TRANSITION. THE SYSTEM WILL EMBED UNDER A 500 MB
SHORTWAVE TROUGH BY TAU 72 AND BEGIN ENTRAINING DRY, COOL
NORTHWESTERLY WINDS INTO THE CORE OF THE SYSTEM. THE SYSTEM WILL
DEVELOP COLD AND WARM FRONTS AND COMPLETE ETT NO LATER THAN TAU 96
AS STRONG STORM-FORCE LOW TO THE EAST OF HOKKAIDO.  

MODEL DISCUSSION: TRACK GUIDANCE REMAINS IN VERY GOOD AGREEMENT,
BOTH IN THE CROSS AND ALONG-TRACK ASPECTS. CROSS-TRACK SPREAD IS 55
NM AT TAU 48, INCREASING TO 125 NM AT TAU 120. ALONG-TRACK SPREAD
HAS DECREASED SINCE THE PREVIOUS RUNS, NOW DOWN TO A MODEST 200 NM
AT TAU 96. OVERALL CONFIDENCE IN THE TRACK FORECAST IS HIGH
THROUGHOUT THE FORECAST PERIOD. INTENSITY GUIDANCE IS ALSO IN GOOD
AGREEMENT ON THE OVERALL SCENARIO OF NEAR-TERM INTENSIFICATION
FOLLOWED BY STEADY WEAKENING. THE JTWC FORECAST LIES ABOUT 10 KNOTS
ABOVE THE CONSENSUS MEAN THROUGH THE FORECAST WITH MEDIUM
CONFIDENCE. 

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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