Advisories

WDPN31 PGTW 270300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 25W (SURIGAE) WARNING NR 016//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 24.6N 127.6E
   INITIAL INTENSITY: 90 KTS
   GEOGRAPHIC REFERENCE: 115 NM SOUTH OF KADENA AB
   MOVEMENT PAST 6 HOURS: NORTH-NORTHEASTWARD AT 07 KTS
   SIGNIFICANT WAVE HEIGHT: 29 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TYPHOON (TY) 25W REMAINS SITUATED WITHIN A HIGHLY FAVORABLE 
ENVIRONMENT WITH DUAL CHANNEL OUTFLOW AND LOW VERTICAL WIND SHEAR.
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A RAPIDLY
CONSOLIDATING, SYMMETRIC CORE, WITH A ROUND EYE, WHICH SUPPORTS THE
INITIAL POSITION WITH HIGH CONFIDENCE. AFTER 270000Z, ENHANCED 
INFRARED SATELLITE IMAGERY INDICATES THE EYE HAS CLEARED QUICKLY,
WITH EYE TEMPERATURES NOW NEAR +12C. CONSEQUENTLY, THE 270110Z
CIMSS ADT RAW T-NUMBER HAS SURGED TO T6.4, WITH THE ADJUSTED
T-NUMBER UP TO T5.0. IF THIS IMPROVED STRUCTURE PERSISTS, IT WILL
BE REFLECTED IN THE NEXT WARNING ANALYSIS AT 270600Z. THE SYSTEM
HAS MAINTAINED A COMPACT CORE OF GALE- AND STORM-FORCE WINDS AS
INDICATED IN AN EARLIER ASCATUHR BULLSEYE IMAGE. SURFACE OBSERVATIONS 
AT KADENA AB HAVE INCREASED TO ABOUT 20 KNOTS SUSTAINED WITH GUSTS TO 
30 KNOTS. THE INITIAL INTENSITY IS ASSESSED AS OF 270000Z AT 90 KNOTS 
BASED ON THE SUBJECTIVE DVORAK ESTIMATES RANGING FROM 90-102 KNOTS, 
WITHIN THE 82-97 KNOT RANGE OF CIMSS OBJECTIVE ESTIMATES.

INITIAL WIND RADII BASIS: PERSISTENCE 

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.0 - 90 KTS
   RJTD: T5.0 - 90 KTS
   RCTP: T5.5 - 102 KTS
   CIMSS SATCON: 95 KTS AT 262318Z
   CIMSS ADT: 82 KTS AT 262340Z
   CIMSS AIDT: 83 KTS AT 262340Z
   CIMSS D-MINT: 96 KTS AT 262348Z
   CIMSS D-PRINT: 97 KTS AT 270040Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE
   VWS: 15-20 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG DUAL-CHANNEL

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: MEDIUM
   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 HAS TURNED GRADUALLY ONTO A NORTH-
NORTHEASTWARD TRAJECTORY BUT HAS CONTINUED TO WOBBLE. TY 25W WILL 
TRACK NORTH-NORTHEASTWARD THROUGH TAU 12 THEN WILL TURN NORTHEASTWARD 
BY TAU 24 AS IT ROUNDS THE NORTHWEST PERIPHERY OF THE STR. ALTHOUGH 
RAPID INTENSIFICATION IS NOT EXPLICITLY FORECAST OVER THE NEXT 24 
HOURS, THE SYSTEM WILL INTENSIFY SIGNIFICANTLY TO A PEAK OF 100 KNOTS 
BY TAU 12, WITH A HIGHER PEAK INTENSITY POSSIBLE IF THE EYE CAN 
MAINTAIN AND EYE TEMPERATURES WARM FURTHER. AFTER TAU 24, THE SYSTEM 
WILL TRACK ALONG THE NORTHWESTERN PERIPHERY OF THE STR ON A 
NORTHEASTWARD TRAJECTORY THROUGH TAU 72. TY 25W WILL GRADUALLY WEAKEN 
AS IT ENCOUNTERS INCREASING VERTICAL WIND SHEAR OF 20-25 KNOTS 
ASSOCIATED WITH THE MIDLATITUDE WESTERLIES. AFTER TAU 72, THE SYSTEM 
WILL ACCELERATE NORTHEASTWARD WITHIN THE MIDLATITUDE WESTERLIES AND 
COMMENCE EXTRA-TROPICAL TRANSITION (ETT) AS IT TRACKS ALONG THE 
SOUTHERN PERIPHERY OF THE BAROCLINIC ZONE. STEADY WEAKENING WILL OCCUR 
DUE TO DRY AIR ENTRAINMENT AND STRONG VERTICAL WIND SHEAR OF 30-40 
KNOTS. TY 25W WILL COMPLETE ETT BY TAU 120 AS IT GAINS FRONTAL 
CHARACTERISTICS AND BECOMES EMBEDDED IN THE MIDLATITUDE WESTERLIES.   

MODEL DISCUSSION: WITH THE EXCEPTION OF NAVGEM, THE CONSENSUS
MODELS REMAIN IN TIGHT AGREEMENT THROUGH TAU 24, WITH A 10-45NM
CROSS-TRACK SPREAD FROM TAU 12 TO TAU 24 AS THE SYSTEM PASSES EAST
OF OKINAWA. GFS REMAINS THE SOLE OUTLIER BUT NOW INDICATES A MORE 
PROLONGED NORTHEASTWARD TRACK AND STALL SOUTH OF SHIKOKU AS THE STR 
BUILDS TO THE EAST CUTTING OFF ANY POLEWARD PROGRESS. AFTER TAU 120, 
GFS THEN TRACKS 25W SHARPLY SOUTHWARD AS IT UNDERGOES FUJIWHARA WITH 
AN APPROACHING LARGE TROPICAL CYCLONE THAT IT FORECASTS TO RAPIDLY 
DEVELOP EAST OF THE NORTHERN MARIANAS WITHIN THE NEXT 2-3 DAYS. THE 
REMAINDER OF THE CONSENSUS MODELS REMAIN SPLIT ON THE ALONG TRACK 
SPEED WITH MAJOR DIFFERENCES. ADDITIONALLY, ECMI HAS BEEN VERY ERRATIC 
RUN-TO-RUN, AND NOW INDICATES A SIGNIFICANTLY SLOWER TRACK. THE ECMWF 
ENSEMBLE NOW SHOWS MANY SOLUTIONS STALLING SOUTH OF JAPAN, WITH A 
CHECK MARK TYPE TRACK BACK TO THE SOUTHWEST. THEREFORE, AN ALTERNATE 
SCENARIO IS STILL POSSIBLE ALTHOUGH CONSIDERED LOW PROBABILITY AT THIS 
TIME. THE BULK OF THE ENSEMBLE GUIDANCE INCLUDING THE AIFS-EPS, GEFS, 
AI GEFS AND FNV3-EPS (GOOGLE DEEPMIND) SUPPORT THE JTWC TRACK 
FORECAST, WITH A FAIRLY RAPID NORTHEASTWARD TRACK THROUGH THE FORECAST 
PERIOD. AFTER TAU 72, THERE IS LOW CONFIDENCE IN THE JTWC TRACK 
FORECAST DUE TO LARGE ALONG-TRACK SPEED DIFFERENCES IN THE GUIDANCE. 
RELIABLE INTENSITY GUIDANCE INDICATES A PEAK INTENSITY RANGING FROM 
90-110 KNOTS THROUGH TAU 24 WITH GRADUAL WEAKENING THROUGH TAU 120. 

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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