Advisories

WDPN31 PGTW 262100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 25W (SURIGAE) WARNING NR 015//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 24.0N 127.2E
   INITIAL INTENSITY: 75 KTS
   GEOGRAPHIC REFERENCE: 153 NM SOUTH-SOUTHWEST OF KADENA AB
   MOVEMENT PAST 6 HOURS: NORTH-NORTHEASTWARD AT 06 KTS
   SIGNIFICANT WAVE HEIGHT: 27 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TYPHOON (TY) 25W REMAINS SITUATED WITHIN A HIGHLY FAVORABLE
ENVIRONMENT WITH DUAL CHANNEL OUTFLOW, AND HAS FLIRTED WITH AN EYE
OVER THE PAST SIX HOURS AS IT WOBBLES SLOWLY POLEWARD. ANIMATED
ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS AN ASYMMETRIC,
CLOUD-FILLED EYE, SURROUNDED BY A CONSOLIDATING EYEWALL. ANIMATED
RADAR IMAGERY AND THE CORRESPONDING RADAR FIXES REVEAL A WELL-
DEFINED EYE, WHICH SUPPORTS THE INITIAL POSITION WITH HIGH 
CONFIDENCE, AND INDICATE THE SYSTEM IS GRADUALLY TURNING TOWARD THE 
NORTH-NORTHEAST AS EXPECTED. THE INITIAL INTENSITY IS ASSESSED AT 75 
KNOTS BASED ON THE PGTW T4.5 (77 KNOTS) ESTIMATE AS WELL AS A 
261748Z SATCON ESTIMATE OF 76 KNOTS. AFTER 261800Z, THERE HAS BEEN A 
SHARP JUMP IN THE CIMSS RAW T-NUMBER ESTIMATE TO T6.0 (115 KNOTS) 
CORRESPONDING WITH THE FORMATION OF A WELL-DEFINED EYE. IF THIS 
IMPROVED STRUCTURE PERSISTS, IT WILL BE REFLECTED IN THE NEXT 
WARNING ANALYSIS AT 270000Z. THE SYSTEM HAS MAINTAINED A COMPACT 
CORE OF GALE- AND STORM-FORCE WINDS AS INDICATED IN A 261138Z 
ASCATUHR BULLSEYE IMAGE.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   RJTD: T4.0 - 65 KTS
   CIMSS SATCON: 76 KTS AT 261748Z
   CIMSS ADT: 65 KTS AT 261740Z
   CIMSS AIDT: 68 KTS AT 261740Z
   CIMSS D-MINT: 88 KTS AT 261750Z
   CIMSS D-PRINT: 86 KTS AT 261840Z

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: MEDIUM

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: TRACK SPEEDS HAVE INCREASED AFTER TAU 
72 SINCE THE SYSTEM IS TRACKING UNDER STRONGER WESTERLIES AS IT 
MOVES POLEWARD.   

FORECAST DISCUSSION: TY 25W IS FORECAST TO TURN GRADUALLY NORTH-
NORTHEASTWARD TO NORTHEASTWARD OVER THE NEXT 24 HOURS 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 95 KNOTS BY TAU 12, WITH A 
HIGHER PEAK INTENSITY POSSIBLE IF THE EYE CAN MAINTAIN AND EYE 
TEMPERATURES WARM. 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 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.             

MODEL DISCUSSION: WITH THE EXCEPTION OF NAVGEM, THE CONSENSUS
MODELS REMAIN IN TIGHT AGREEMENT THROUGH TAU 36, WITH A 25-40NM
CROSS-TRACK SPREAD FROM TAU 12 TO TAU 36 AS THE SYSTEM PASSES EAST
OF OKINAWA. AFTER TAU 36, GFS CONTINUES TO STALL THE SYSTEM AS THE
STR BUILDS TO THE EAST CUTTING OFF ANY POLEWARD PROGRESS THEN TRACKS 
IT SHARPLY SOUTHWESTWARD AS IT INTERACTS WITH AN APPROACHING LARGE
TROPICAL SYSTEM THAT IT FORECASTS TO RAPIDLY DEVELOP EAST OF THE
NORTHERN MARIANAS WITHIN THE NEXT FEW DAYS. CURRENTLY GFS IS THE
SOLE OUTLIER AS ALL OTHER CONSENSUS MODELS NOW SUPPORT THE JTWC
TRACK SCENARIO. HOWEVER, THE GFS SOLUTION, WHICH HAS BEEN VERY
CONSISTENT OVER THE PAST TWO DAYS REMAINS A POSSIBLE ALTERNATE
SCENARIO, WHICH IS BEING MONITORED CLOSELY. THE AI GUIDANCE REMAINS 
CONSISTENT WITH A FAIRLY RAPID NORTHEASTWARD TRACK THROUGH THE 
FORECAST PERIOD, WITH LOW CONFIDENCE IN THE JTWC TRACK FORECAST 
AFTER TAU 72 DUE TO LARGE ALONG-TRACK SPEED DIFFERENCES IN THE 
GUIDANCE. THE LARGE MAJORITY OF ENSEMBLES INCLUDING THE AI GEFS, 
GOOGLE DEEPMIND, AIFS EPS AND EC EPS SUPPORT THE JTWC TRACK 
FORECAST. AS FAR AS THE JTWC INTENSITY FORECAST, THE MODEL GUIDANCE 
INDICATES A PEAK INTENSITY RANGE FROM 80-113 KNOTS THROUGH TAU 24 
WITH GRADUAL WEAKENING THROUGH TAU 120. THEREFORE, THERE IS MEDIUM 
CONFIDENCE IN THE JTWC INTENSITY FORECAST.                   

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