Advisories

WDPN31 PGTW 210300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 24W (DUJUAN) WARNING NR 023//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 32.4N 138.7E
   INITIAL INTENSITY: 65 KTS
   GEOGRAPHIC REFERENCE: 181 NM SOUTH-SOUTHWEST OF YOKOSUKA, JAPAN
   MOVEMENT PAST 6 HOURS: NORTH-NORTHEASTWARD AT 13 KTS
   SIGNIFICANT WAVE HEIGHT: 30 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TYPHOON 24W
(DUJUAN) WITH DIMPLE EYE FEATURE EMBEDDED IN A COMPACT CENTRAL
DENSE OVERCAST (CDO). THE CORE OF 24W HAS CONTINUED TO ORGANIZE
OVER THE PAST 6 HOURS, SUGGESTING THAT THE SYSTEM HAS STARTED ON
THE EXPECTED INTENSIFICATION TREND. A 202118Z WSFM 37 GHZ MICROWAVE
IMAGE REVEALED THAT A SMALL, DEFINED MICROWAVE EYE HAS DEVELOPED.
THE RADIUS OF MAXIMUM WINDS HAS BEEN ANALYZED TO HAVE SHRUNK SINCE
THE PREVIOUS WARNING IN RESPONSE TO THE CONSOLIDATED AND STRUCTURED
APPEARANCE SEEN IN MICROWAVE IMAGERY. THE INITIAL POSITION IS
PLACED WITH HIGH CONFIDENCE BASED ON THE ANIMATED MSI AND
EXTRAPOLATION FROM THE WSFM IMAGE. ADDITIONALLY, 24W HAS RECENTLY
ENTERED THE RANGE OF THE JAPAN RADAR NETWORK, FURTHER SUPPORTING
THE INITIAL POSITION LOCATION. THE INITIAL INTENSITY OF 65 KTS IS
ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE AGENCY DVORAK AND
CIMSS INTENSITY ESTIMATES LISTED BELOW. ENVIRONMENTAL ANALYSIS
INDICATES THAT 24W IS PLACED WITHIN A MARGINALLY FAVORABLE
ENVIRONMENT CHARACTERIZED BY ROBUST POLEWARD OUTFLOW ALOFT, LOW TO
MODERATE (15-20 KTS) SOUTHERLY VERTICAL WIND SHEAR, DRY AIR
ENTRAINMENT, AND WARM (28-29 C) SEA SURFACE TEMPERATURES.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: THE NORTHWESTERN PERIPHERY OF A
SUBTROPICAL RIDGE (STR) CENTERED EAST-SOUTHEAST OF JAPAN


AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.0 - 65 KTS
   RJTD: T4.5 - 77 KTS
   RCTP: T4.5 - 77 KTS
   CIMSS SATCON: 65 KTS AT 202200Z
   CIMSS ADT: 55 KTS AT 202330Z
   CIMSS AIDT: 53 KTS AT 202330Z
   CIMSS D-MINT: 71 KTS AT 210056Z
   CIMSS D-PRINT: 73 KTS AT 202330Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 15-20 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG POLEWARD
   OTHER FACTORS: DRY AIR ENTRAINMENT

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: TY 24W HAS STARTED TURNING MORE NORTHEASTWARD
OVER THE LAST 6 HOURS AS IT CONTINUES TO ROUND THE STEERING RIDGE
TO THE EAST. 24W IS FORECAST TO PASS EAST OF THE BOSO PENINSULA IN
ABOUT 12 HOURS WITH THE CPA TO YOKOSUKA EXPECTED NEAR 210900Z.
AFTER TAU 12, TRACK SPEEDS WILL BEGIN TO INCREASE AS 24W TRAVERSES
THE NORTHERN EXTENT OF THE STR AND STARTS TO INTERACT WITH THE STRONG 
MID-LATITUDE WESTERLIES. EXTRATROPICAL TRANSITION IS FORECAST TO BEGIN 
AT TAU 36 WITH COMPLETION AROUND TAU 48, ONCE THE SYSTEM BECOMES 
FURTHER EMBEDDED UNDER THE UPPER-LEVEL JET AND THERMAL ADVECTION 
INCREASES. IN TERMS OF INTENSITY, 24W IS FORECAST TO SLIGHTLY 
INTENSIFY OVER THE NEXT 24 HOURS TO A PEAK INTENSITY OF AROUND 75 KTS. 
THIS BOUT OF INTENSIFICATION IS DUE PRIMARILY TO THE SYSTEM TAPPING 
INTO AN EXCEPTIONAL POLEWARD OUTFLOW CHANNEL, SUPPORTED BY A STRONG 
150+ KNOT JET MAXIMUM SITUATED NORTHEAST OF HOKKAIDO. AFTER TAU 24,
WESTERLY VERTICAL WIND SHEAR AND DRY AIR ENTRAINMENT WILL DRAMATICALLY 
INCREASE. IN ADDITION, SEA SURFACE TEMPERATURES WILL DROP AFTER 24W 
CLEARS THE KUROSHIO CURRENT. AS A RESULT, 24W IS FORECAST TO WEAKEN AS 
IT TRANSITIONS INTO A COLD-CORE CYCLONE.

MODEL DISCUSSION: MODEL TRACK GUIDANCE REMAINS IN VERY GOOD AGREEMENT 
WITH A CROSS-TRACK SPREAD OF JUST 30 NM AT TAU 24. AFTER TAU 24, 
MODELS DIVERGE, MOSTLY IN THE ALONG-TRACK DIRECTION. AT TAU 48, THE 
ALONG-TRACK SPREAD IS MEASURED TO BE ABOUT 250 NM WITH GALWEM BEING 
THE MARKEDLY SLOWEST MODEL AND EC-AIFS BEING THE FASTEST. WHEN 
DISCOUNTING THOSE TWO OUTLIERS, THE REMAINDER OF GUIDANCE SITS WITHIN 
A 110 NM ALONG-TRACK SPREAD. THE JTWC TRACK FORECAST IS PLACED NEAR 
THE MULTI-MODEL CONSENSUS THROUGH TAU 24 AND THEN A BIT FASTER THROUGH 
TAU 48 TO OFFSET GALWEM. INTENSITY GUIDANCE IS IN SLIGHTLY WORSE 
AGREEMENT THIS MODEL RUN WITH HAFS-A NOW SHOWING A PEAK INTENSITY OF 
85 KTS AT TAU 24, WHICH IS NOT OUT OF THE QUESTION CONSIDERING THE 
RECENT STRUCTURAL EVOLUTION. THE REMAINDER OF GUIDANCE DEPICTS PEAK
INTENSITIES RANGING FROM 65-75 KTS. ALL MODELS THEN AGREE ON WEAKENING 
AFTER TAU 24. THE JTWC INTENSITY FORECAST IS PLACED CLOSE TO THE 
CONSENSUS WITH MEDIUM CONFIDENCE.

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