Advisories

WDPN31 PGTW 212100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 24W (DUJUAN) WARNING NR 026//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 36.9N 144.1E
   INITIAL INTENSITY: 70 KTS
   GEOGRAPHIC REFERENCE: 234 NM EAST-NORTHEAST OF YOKOSUKA, JAPAN
   MOVEMENT PAST 6 HOURS: NORTHEASTWARD AT 27 KTS
   SIGNIFICANT WAVE HEIGHT: 34 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TYPHOON
(TY) 24W (DUJUAN) WITH A PARTIALLY EXPOSED LOW LEVEL CIRCULATION
CENTER (LLCC) AND AN OVERALL DETERIORATING CONVECTIVE STRUCTURE.
CLOUD TOP TEMPERATURES OF THE OUTER RAIN BAND ON THE NORTHERN FLANK
HAVE WARMED FROM -60 C TO -40 C, ALTHOUGH A CENTRAL DENSE OVERCAST
(CDO) HAS PERSISTED, ALBEIT SHEARED SLIGHTLY TO THE NORTHEAST OF
THE LLCC. A 211427Z 89 GHZ GPM IMAGE SHOWS THE PREVIOUSLY CLOSED
MICROWAVE EYE FEATURE HAS ERODED AND OPENED IN THE SOUTHWESTERN
QUADRANT. ENVIRONMENTAL CONDITIONS ARE ASSESSED AS MARGINALLY
UNFAVORABLE AS TY 24W NEARS THE END OF THE KUROSHIO CURRENT, WHICH IS 
CURRENTLY PROVIDING MODERATELY WARM (27-28 C) SEA SURFACE 
TEMPERATURES. THE SYSTEM ALSO HAS STRONG POLEWARD OUTFLOW ALOFT DUE TO 
THE STRONG UPPER-LEVEL WESTERLIES, HOWEVER THIS IS ALSO IMPARTING HIGH 
(25-30KTS) VERTICAL WIND SHEAR (VWS) AND SIGNIFICANT DRY AIR
ENTRAINMENT TO 24W. THE INITIAL POSITION IS PLACED WITH HIGH
CONFIDENCE BASED ON SATELLITE IMAGERY AND AGENCY FIXES. THE INITIAL
INTENSITY IS ALSO ASSESSED WITH HIGH CONFIDENCE, BASED ON THE
AGENCY DVORAK FIXES AND CIMSS OBJECTIVE ESTIMATES LISTED BELOW.

INITIAL WIND RADII BASIS: WIND RADII ADJUSTED BASED ON 211206
METOP-C ASCAT UHR DATA. 

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) CENTERED TO THE
SOUTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   RCTP: T4.5 - 77 KTS
   CIMSS SATCON: 63 KTS AT 211558Z
   CIMSS ADT: 51 KTS AT 211730Z
   CIMSS AIDT: 48 KTS AT 211730Z
   CIMSS D-MINT: 65 KTS AT 211559Z
   CIMSS D-PRINT: 66 KTS AT 211630Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY
UNFAVORABLE
   VWS: 25-30 KTS
   SST: 28-27 CELSIUS
   OUTFLOW: STRONG POLEWARD
   OTHER FACTORS: DRY AIR ENTRAINMENT

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: EXTRATROPICAL TRANSITION (ETT) ASSESSED 
TO HAVE BEGUN. ETT EXPECTED TO COMPLETE SOONER THAN PREVIOUSLY 
FORECAST.

FORECAST DISCUSSION: TY 24W IS FORECAST TO CONTINUE ACCELERATING
NORTHEASTWARD FOR THE REMAINDER OF THE FORECAST PERIOD, STEERED BY
THE SUBTROPICAL RIDGE (STR) CENTERED TO THE SOUTHEAST.
EXTRATROPICAL TRANSITION (ETT) IS ASSESSED TO HAVE BEGUN AS TY 24W
IS SITUATED ON THE EQUATORWARD EDGE OF THE UPPER-LEVEL JET, CAUSING
THE LLCC TO ELONGATE AS HIGH VWS FROM THE UPPER-LEVEL WESTERLIES
SHEARS THE CONVECTION TO THE NORTHEASTERN FLANK AND ENTRAINS
LARGE AMOUNTS OF DRY AIR INTO THE SYSTEM. ETT IS FORECAST TO
COMPLETE BY TAU 24. REGARDING INTENSITY, TY 24W IS FORECAST TO
BEGIN A WEAKENING TREND FOR THE REMAINDER OF THE FORECAST PERIOD AS
THE SYSTEM WILL IMMINENTLY CROSS THE 26 C ISOTHERM AND VWS IS
INCREASES TO OVER 30 KTS. THE SYSTEM IS EXPECTED TO REMAIN AT TROPICAL 
STORM INTENSITY AS IT COMPLETES ETT BY TAU 24.

MODEL DISCUSSION: TRACK MODEL GUIDANCE IS IN GOOD AGREEMENT FOR THE
REMAINDER OF THE FORECAST PERIOD, WITH SLIGHTLY LESS AGREEMENT IN
ALONG-TRACK SPEED WITH 90 NM OF ALONG-TRACK SPREAD AT TAU 24.
THE OFFICIAL JTWC FORECAST TRACK IS PLACED WITH HIGH CONFIDENCE IN
GOOD AGREEMENT WITH THE MULTI-MODEL CONSENSUS AND GOOGLE DEEPMIND.
INTENSITY MODEL GUIDANCE IS ALSO IN GOOD AGREEMENT ON A GRADUAL
WEAKENING OUT TO TAU 12 FOLLOWED BY A MUCH SHARPER DECREASE IN
INTENSITY THEREAFTER. THE OFFICIAL JTWC INTENSITY FORECAST IS
ASSESSED WITH HIGH CONFIDENCE, SLIGHTLY ABOVE THE MULTI-MODEL
CONSENSUS.

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