Advisories

WDPN31 PGTW 270900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 25W (SURIGAE) WARNING NR 017//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 25.4N 128.3E
   INITIAL INTENSITY: 105 KTS
   GEOGRAPHIC REFERENCE: 71 NM SOUTH-SOUTHEAST OF KADENA AB
   MOVEMENT PAST 6 HOURS: NORTHEASTWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 33 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TYPHOON (TY)
25W (SURIGAE) AS A STRONG TYPHOON WITH A CLOUD-FREE AND SYMMETRIC
EYE MEASURING APPROXIMATELY 17 NM IN DIAMETER. PREVIOUS TO ABOUT
270730Z, 25W WAS STRUGGLING TO CLEAR ITS EYE AND MAINTAIN SYMMETRY,
BUT THE STORM QUICKLY STABLIZED ITS CORE AND ANIMATED MSI NOW
DEPICTS A ROBUST SYSTEM. 25W MAY INTENSIFY FURTHER OVER THE NEXT
FEW HOURS IF IT IS ABLE TO MAINTAIN ITS CURRENT PRESENTATION. 25W
IS CURRENTLY TRACKING PARALLEL TO THE EASTERN COAST OF OKINAWA AND
IS NEARLY AT ITS CLOSEST POINT OF APPROACH TO KADENA AIR BASE.
SURFACE OBSERVATION STATIONS FROM SOUTHERN OKINAWA ARE REPORTING
SUSTAINED WINDS OF NEARLY 30 KTS. ENVIRONMENTAL ANALYSIS REVEALS A
HIGHLY FAVORABLE ENVIRONMENT CHARACTERIZED BY LOW (10-15 KTS)
VERTICAL WIND SHEAR (VWS), WARM (29-30 C) SEA SURFACE TEMPERATURES
(SST), AND ROBUST DUAL-CHANNEL OUTFLOW. THE INITIAL POSITION IS
PLACED WITH HIGH CONFIDENCE BASED ON THE WELL-DEFINED EYE. THE
INITIAL INTENSITY OF 105 KTS IS ASSESSED WITH MEDIUM CONFIDENCE
BASED ON THE CIMSS AUTOMATIC INTENSITY ESTIMATES AND AGENCY DVORAK
FIXES LISTED BELOW.

INITIAL WIND RADII BASIS: UPDATED WIND RADII USING THE 027004Z
ASCAT UHR DATA

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T6.0 - 115 KTS
   RJTD: T6.0 - 115 KTS
   CIMSS SATCON: 109 KTS AT 270610Z
   CIMSS ADT: 119 KTS AT 270610Z
   CIMSS AIDT: 104 KTS AT 270610Z
   CIMSS D-MINT: 100 KTS AT 270504Z
   CIMSS D-PRINT: 103 KTS AT 270610Z

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: HIGH

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

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 UPWARDS OF 30-40 KTS BY TAU 72, FURTHER COMPOUNDING
WEAKENING. 25W IS FORECAST TO BEGIN EXTRATROPICAL TRANSITION
BETWEEN TAU 72-96 AND COMPLETE TRANSITION NO LATER THAN TAU 120.
REGARDING INTENSITY, A PEAK INTENSITY HIGHER THAN 105 KTS IS
EXPECTED TO OCCUR AT TAU 6 THAT IS UNABLE TO BE REFLECTED IN THE
OFFICIAL JTWC FORECAST. FOLLOWING TAU 12, 25W IS FORECAST TO
STEADILY DETERIORATE FOR THE REMAINDER OF THE FORECAST PERIOD AS IT
ENCOUNTERS INCREASINGLY HOSTILE CONDITIONS AND UNDERGOES
EXTRATROPICAL TRANSITION. 

MODEL DISCUSSION: DETERMINISTIC MODEL TRACK GUIDANCE IS IN GOOD
AGREEMENT THROUGH TAU 36. AT THAT POINT, ALONG-TRACK SPREAD BECOMES
INCREASINGLY APPARENT, PARTICULARLY BETWEEN PHYSICS-BASED MODELS
AND EXPERIMENTAL AI-BASED MODELS. GFS NO LONGER DEPICTS BINARY
INTERACTION WITH A FUTURE STRONG SYSTEM TO THE SOUTHEAST, BUT
REMAINS SLIGHTLY SLOWER THAN OTHER MODEL GUIDANCE AND NOW DEPICTS A
SHARP TURN THAT WOULD TAKE THE STORM JUST OFFSHORE OF THE CHIBA
PREFECTURE. THE PROBABILITY OF BINARY INTERACTION WITH A FUTURE
STORM IS BECOMING INCREASINGLY UNLIKELY AND IS NOT REFLECTED IN THE
OFFICIAL JTWC FORECAST. ECMWF MODELS CONTINUE TO DEPICT A
SIGNIFICANTLY SLOWER TRACK, THOUGH TRACK SPEEDS ARE INCREASING WITH
EACH SUBSEQUENT MODEL RUN. AS SUCH, THE JTWC TRACK FORECAST IS
PLACED CLOSE TO THE MULTI-MODEL CONSENSUS CONTAINING RELIABLE
PHYSICS-BASED MODELS AND THE EXPERIMENTAL MULTI-MODEL CONSENSUS
CONTAINING THE EXPERIMENTAL AI MODELS. THE JTWC TRACK FORECAST IS
PLACED WITH MEDIUM CONFIDENCE FROM TAU 0-72 AND LOW CONFIDENCE FROM
TAU 72-120, WITH UNCERTAINTY STEMMING FROM LARGE ALONG-TRACK SPREAD
AFTER TAU 36. RELIABLE INTENSITY AIDS ARE IN MODERATE AGREEMENT IN
A STEADY WEAKENING TREND THROUGH TAU 120, THOUGH NONE OF THE MODELS
REFLECT THE SIGNIFICANT INTENSIFICATION CURRENTLY OCCURRING. AS A
RESULT, THE JTWC INTENSITY FORECAST IS PLACED 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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