Advisories

WDPN31 PGTW 280900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 25W (SURIGAE) WARNING NR 021//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 27.5N 131.6E
   INITIAL INTENSITY: 100 KTS
   GEOGRAPHIC REFERENCE: 212 NM EAST-NORTHEAST OF KADENA AB
   MOVEMENT PAST 6 HOURS: NORTHEASTWARD AT 11 KTS
   SIGNIFICANT WAVE HEIGHT: 40 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TYPHOON (TY)
25W WITH PARTIALLY EXPOSED LOW-LEVEL BANDING ALONG THE WESTERN
PERIPHERY IN RESPONSE TO THE SUBSTANTIAL INCREASE IN VERTICAL WIND
SHEAR (VWS) OVER THE PAST SEVERAL HOURS. THE MODERATE TO HIGH
(20-25) VWS IS COMPRESSING THE DEEP CONVECTION ON THE WESTERN EDGE
AND SUPPRESSING POLEWARD OUTFLOW. ADDITIONALLY, THERE IS
CONSIDERABLE DRY AIR TO THE WEST AND NORTH OF THE SYSTEM. 25W ALSO
PRODUCED A CONSIDERABLE COOL WAKE AFTER IT RAPIDLY INTENSIFIED, AND
AS A RESULT, THE ABUNDANT SUPPORT OF THE ELEVATED SEA SURFACE
TEMPERATURES AND OCEAN HEAT CONTENT DECREASED QUICKLY. THESE
CONDITIONS CONTRIBUTED TO THE STORM'S RAPID WEAKENING TREND AND
MARGINALLY FAVORABLE ENVIRONMENT. THE INITIAL POSITION IS PLACED
WITH LOW CONFIDENCE BASED ON THE FULLY OBSCURED LOW LEVEL
CIRCULATION CENTER AND PARTIALLY EXPOSED CLOUD BANDING. THE INITIAL
INTENSITY OF 100 KTS IS ASSESSED WITH LOW CONFIDENCE BASED ON THE
AGENCY DVORAK DATA-T VALUES OF 5.0 (90 KTS) AND THE CIMSS AUTOMATED
INTENSITY ESTIMATES LISTED BELOW.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: THE WESTERN PERIPHERY OF THE DEEP-LAYER
SUBTROPICAL RIDGE (STR) POSITIONED TO THE SOUTHEAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T6.0 - 115 KTS
   RJTD: T6.5 - 127 KTS
   CIMSS SATCON: 88 KTS AT 280444Z
   CIMSS ADT: 107 KTS AT 280540Z
   CIMSS AIDT: 99 KTS AT 280540Z
   CIMSS D-MINT: 102 KTS AT 280445Z
   CIMSS D-PRINT: 71 KTS AT 280540Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 20-25 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: MODERATE EQUATORWARD
   OTHER FACTORS: RELATIVELY DRY SURROUNDING ENVIRONMENT TO THE
NORTH AND WEST

ANALYSIS CONFIDENCE:
   INITIAL POSITION: LOW
   INITIAL INTENSITY: LOW
   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 25W (SURIGAE) IS FORECAST TO CONTINUE
TRACKING GENERALLY NORTHEASTWARD FOR THE DURATION OF THE FORECAST
PERIOD. 25W IS FORECAST TO MAINTAIN A RELATIVELY CONSISTENT TRACK
SPEED UNTIL ABOUT TAU 60, AT WHICH POINT IT WILL BEGIN TO INTERACT
WITH THE MID-LATITUDE WESTERLIES AND ACCELERATE POLEWARD. BETWEEN
TAU 60-72, 25W IS EXPECTED TO CROSS THE 26C ISOTHERM WHILE
SIMULTANEOUSLY ENCOUNTERING A HOSTILE ENVIRONMENT CHARACTERIZED BY
DRY AIR AND HIGH (25-30 KTS) VWS. AROUND THIS TIME, 25W IS FORECAST
TO BEGIN EXTRATROPICAL TRANSITION (ETT) AND COMPLETE TRANSITION
BETWEEN TAU 72-96. REGARDING INTENSITY, 25W IS EXPECTED TO RAPIDLY
WEAKEN THROUGH TAU 24, FOLLOWED BY A MORE GRADUAL WEAKENING TREND
THROUGH TAU 48 AS THE VWS ABATES SLIGHTLY. INTENSITY IS EXPECTED TO
REMAIN RELATIVELY STABLE AS SURIGAE UNDERGOES ETT.

MODEL DISCUSSION: DETERMINISTIC MODEL TRACK GUIDANCE IS COMING INTO
BETTER AGREEMENT WITH REGARD TO CROSS-TRACK SPREAD, BUT RETAINS A
SIGNIFICANT ALONG-TRACK SPREAD, PARTICULARLY AFTER TAU 60. THE JTWC
TRACK FORECAST REMAINS CONSISTENT AND IS BASED ON BOTH THE
MULTI-MODEL PHYSICS-BASED AND AI-BASED CONSENSUSES. AS A RESULT,
THE JTWC TRACK FORECAST IS PLACED WITH MEDIUM CONFIDENCE FROM TAU
0-72 AND LOW CONFIDENCE FROM TAU 72-96. RELIABLE INTENSITY GUIDANCE
IS IN GOOD AGREEMENT ON AN INITIAL DRASTIC WEAKENING TREND,
FOLLOWED BY A GRADUAL WEAKENING TREND, AND FINALLY A RELATIVELY
STEADY INTENSITY AS 25W BECOMES EXTRATROPICAL BETWEEN TAU 72-96. THE 
JTWC INTENSITY FORECAST IS IN CLOSE ALIGNMENT WITH THE MULTI-MODEL
CONSENSUS AND IS ASSESSED WITH OVERALL MEDIUM CONFIDENCE.

FORECAST CONFIDENCE:
   TRACK 00-72 HR: MEDIUM
   TRACK 72-120 HR: LOW
   INTENSITY 00-72 HR: MEDIUM
   INTENSITY 72-120 HR: MEDIUM//
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