Advisories

WDPN31 PGTW 271500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 25W (SURIGAE) WARNING NR 018//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 25.9N 129.1E
   INITIAL INTENSITY: 125 KTS
   GEOGRAPHIC REFERENCE: 76 NM EAST-SOUTHEAST OF KADENA AB
   MOVEMENT PAST 6 HOURS: NORTHEASTWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 45 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TYPHOON
(TY) 25W (SURIGAE) AS A ROBUST AND POWERFUL SYSTEM THAT RECENTLY
RAPIDLY INTENSIFIED TO 125 KTS. 25W INTENSIFIED 50 KTS WITHIN THE
PAST 24 HOURS -- STRENGTHENING FROM 75 KTS AT 261200Z TO 125 KTS AT
271200Z -- WITH AN INTENSIFICATION OF 30 KTS IN JUST THE PAST 12
HOURS ALONE. THIS SCALE OF INTENSIFICATION WAS UNEXPECTED, GIVEN
THAT 25W STILL STRUGGLED TO ESTABLISH A CLOUD-FREE EYE AS RECENTLY
AS 6 HOURS AGO. THE ENVIRONMENT REMAINS HIGHLY FAVORABLE,
CHARACTERIZED BY LOW (10-15 KTS) VERTICAL WIND SHEAR (VWS), WARM
(29-30 C) SEA SURFACE TEMPERATURES, AND ROBUST DUAL-CHANNEL
OUTFLOW. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED
ON THE WELL-DEFINED EYE IN ANIMATED EIR. THE INITIAL INTENSITY OF
125 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE STRONG
AGREEMENT BETWEEN THE AGENCY DVORAK FIXES AND CIMSS AUTOMATED
INTENSITY ESTIMATES LISTED BELOW.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: DEEP-LAYER SUBTROPICAL RIDGE (STR)
POSITIONED TO THE EAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T6.5 - 127 KTS
   RJTD: T6.5 - 127 KTS
   RCTP: T6.5 - 127 KTS
   CIMSS SATCON: 125 KTS AT 271210Z
   CIMSS ADT: 129 KTS AT 271210Z
   CIMSS AIDT: 122 KTS AT 271300Z
   CIMSS D-MINT: 115 KTS AT 271034Z
   CIMSS D-PRINT: 124 KTS AT 271210Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE
   VWS: 10-15 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG DUAL-CHANNEL

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: TY 25W UNDERWENT UNEXPECTEDLY RAPID 
INTENSIFICATION
TO 125 KTS. THE FORECAST HAS BEEN UPDATED TO REFLECT HIGHER
INTENSITIES AS THE STORM WEAKENS.

FORECAST DISCUSSION: TY 25W IS FORECAST TO CONTINUE TRACKING ALONG
THE NORTHWESTERN EXTENT OF THE STR CENTERED TO ITS EAST AND
ACCELERATE POLEWARD FOR THE DURATION OF THE FORECAST PERIOD.
ADDITIONALLY, 25W IS EXPECTED TO REMAIN RELATIVELY COMPACT FOR THE
REST OF ITS LIFESPAN. BEGINNING AROUND TAU 24, VWS IS EXPECTED TO
INCREASE TO ABOUT 20 KTS AND INDUCE DRY AIR ENTRAINMENT FROM THE
NORTHERN SEMICIRCLE, THUS BEGINNING THE STEADY WEAKENING TREND FROM
TAU 24 ONWARD. 25W IS EXPECTED TO CROSS THE 26C ISOTHERM BETWEEN
TAU 72-96, NEARLY SIMULTANEOUS TO THE SYSTEM ENTERING THE
BAROCLINIC ZONE AND BEGINNING JET INTERACTION. VWS IS EXPECTED TO
INCREASE TO OVER 30 KTS BY TAU 72, FURTHER COMPOUNDING WEAKENING.
25W IS FORECAST TO BEGIN EXTRATROPICAL TRANSITION BETWEEN TAU 72
AND COMPLETE TRANSITION NO LATER THAN TAU 96. REGARDING INTENSITY,
25W MAY CONTINUE TO INTENSIFY FOR THE NEXT 6-12 HOURS, BUT IS
CURRENTLY FORECAST TO BEGIN IT'S TERMINAL WEAKENING TREND AT TAU
12. SHOULD 25W CONTINUE TO INTENSIFY BEYOND TAU 12, THE TERMINAL
WEAKENING COULD BE FURTHER DELAYED. REGARDLESS, 25W IS FORECAST TO
WEAKEN AS IT TRACKS POLEWARD INTO INCREASINGLY HOSTILE CONDITIONS
BEFORE ULTIMATELY BECOMING AN EXTRATROPICAL SYSTEM.

MODEL DISCUSSION: DETERMINISTIC MODEL TRACK GUIDANCE IS IN DECENT
AGREEMENT UNTIL TAU 36. AT THAT POINT, OUTLIERS BEGIN TO EMERGE
FROM THE PACK, INCLUDING GFS. THE GEFS MEAN, AND ECMWF. THOSE
MODELS DEPICT A SIGNIFICANTLY SLOWER AND A SLIGHTLY MORE
EQUATORWARD TRACK COMPARED TO OTHER PHYSICS-BASED MODELS AND THE
AI-BASED EXPERIMENTAL MODELS. THE ALONG-TRACK SPREAD COMPOUNDS
BETWEEN TAU 36-96, ULTIMATELY LEADING TO A 730NM ALONG-TRACK SPREAD
AT TAU 96 BETWEEN THE FASTEST MODEL (GSM) AND THE SLOWEST MODEL
(GFS). GFS IS SIGNIFICANTLY SLOWER DUE TO POSSIBLE BINARY
INTERACTION BETWEEN 25W AND A SECOND FUTURE STORM THAT GFS RAPIDLY
FORMS NEAR THE MARIANAS ISLANDS. GFS DEPICTS THE SECOND STORM
HEAVILY INFLUENCING SURIGAE'S TRACK BEFORE ULTIMATELY ABSORBING
25W. THIS SCENARIO IS CONSIDERED TO BE UNLIKELY, DUE TO THE
CONSISTENCY IN AI-BASED MODELS AND OTHER PHYSICS-BASED MODELS THAT
DO NOT DEPICT THIS SCENARIO. THE JTWC TRACK FORECAST IS PLACED
CLOSE TO THE MULTI-MODEL CONSENSUSES FOR PHYSICS-BASED AND AI-BASED
MODELS. DUE TO THE CONSIDERABLE ALONG-TRACK SPREAD THROUGHOUT THE
FORECAST PERIOD, THE JTWC TRACK FORECAST IS PLACED WITH MEDIUM 
CONFIDENCE FROM TAU 0-72 AND LOW CONFIDENCE FROM TAU 72-96. RELIABLE 
INTENSITY AIDS DID NOT ACCURATELY DEPICT THE RECENT RAPID 
INTENSIFICATION AND THEREFORE STRUGGLE TO REFLECT THE HIGHER INITIAL 
INTENSITY IN THE WEAKENING TREND THROUGH TAU 96. THE JTWC INTENSITY 
FORECAST LIES SLIGHTLY HIGHER THAN THE MULTI-MODEL CONSENSUS THROUGH 
TAU 48, REFLECTING A STEADY WEAKENING TREND ACCOUNTING FOR THE HIGHER 
INTENSITIES. AFTER TAU 48, THE JTWC INTENSITY FORECAST IS IN CLOSE 
AGREEMENT WITH THE MULTI-MODEL CONSENSUS AND THE HAFS-A SOLUTION. DUE 
TO THE UNFORECASTED RAPID INTENSIFICATION AND RESULTING UNCERTAINTY 
REGARDING THE INTENSITY FORECAST, THE JTWC INTENSITY FORECAST IS 
ASSESSED WITH OVERALL LOW CONFIDENCE. 

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