WDPN31 PGTW 220900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 02W (SURIGAE) WARNING NR 036//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON 02W (SURIGAE), LOCATED APPROXIMATELY 397 NM SOUTH-
SOUTHWEST OF KADENA AB, HAS TRACKED NORTH-NORTHEASTWARD AT 07 KNOTS 
OVER THE PAST SIX HOURS. THE CURRENT POSITION IS BASED ON RECENT 
ANALYST SATELLITE FIXES FROM PGTW, KNES AND RJTD AND A LOW-LEVEL 
CENTER FEATURE EVIDENT IN A 220452Z AMSR2 36 GHZ MICROWAVE IMAGERY. 
THE INTENSITY OF 90 KNOTS IS CONSISTENT WITH A CONSENSUS OF 
SUBJECTIVE DVORAK T-NUMBER ESTIMATES (RANGING FROM 77 TO 102 KNOTS) 
FROM THE SAME REPORTING AGENCIES. TY 02W HAS TRACKED NORTH-
NORTHEASTWARD OVER THE PAST SIX HOURS WHILE ROUNDING THE AXIS OF A 
SUBTROPICAL STEERING RIDGE SITUATED TO THE EAST. DEEP CONVECTION 
AROUND THE CENTER HAS BECOME INCREASINGLY FRAGMENTED, BUT A 34 NM 
EYE REMAINS CLEARLY EVIDENT IN INFRARED SATELLITE IMAGERY. 
ENVIRONMENTAL ANALYSIS INDICATES MODERATE VERTICAL WIND SHEAR (15-20 
KNOTS), MARGINAL SEA SURFACE TEMPERATURES (26-27 CELSIUS) AND 
FAVORABLY STRONG EASTWARD AND POLEWARD OUTFLOW ALOFT.
3. FORECAST REASONING.
   A. FORECAST WIND RADII IN THE 72 TO 120 HOUR FORECAST PERIOD HAVE 
INCREASED IN SIZE TO REFLECT ANTICIPATED EXPANSION DURING 
EXTRATROPICAL TRANSITION. HOWEVER, THERE IS NO SIGNIFICANT CHANGE TO 
THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING 
MESSAGE.
   B. TY 02W WILL CONTINUE TO TURN EASTWARD AROUND THE SUBTROPICAL 
STEERING RIDGE AXIS OVER THE NEXT 24 TO 36 HOURS. STEADY WEAKENING 
IS EXPECTED UNDER THE INFLUENCE OF INCREASING WESTERLY VERTICAL WIND 
SHEAR AND MARGINAL SEA SURFACE TEMPERATURES. STORM MOTION IS 
EXPECTED TO SLOW AS A SHORTWAVE TROUGH PASSES TO THE NORTH OF THE 
SYSTEM BETWEEN TAU 24 AND TAU 36. THEREAFTER, TY 02W WILL DIP EAST-
SOUTHEASTWARD AS THE STEERING RIDGE REORIENTS TO THE SOUTH OF THE 
SYSTEM. AFTER TAU 48, AN AMPLIFYING MID-LATITUDE TROUGH WILL BEGIN 
TO INTERACT WITH TY 02W AND, FOR THE REST OF THE FORECAST PERIOD, 
THE SYSTEM WILL BECOME EMBEDDED WITHIN THE FLOW ASSOCIATED WITH THIS 
TROUGH. STRONG VERTICAL WIND SHEAR AND PASSAGE OVER COOLER WATER 
WILL LEAD TO STEADY WEAKENING IN THE MEDIUM TERM. HOWEVER, 
BAROCLINIC SUPPORT AHEAD OF THE AFOREMENTIONED MID-LATITUDE TROUGH 
IS EXPECTED TO SUSTAIN THE SYSTEM NEAR STORM FORCE (50 KNOTS) AS THE 
SYSTEM UNDERGOES EXTRATROPICAL TRANSITION. NUMERICAL MODEL GUIDANCE 
IS IN GOOD AGREEMENT THROUGH TAU 72, LENDING HIGH CONFIDENCE TO THE 
INITIAL PORTION OF THE OFFICIAL TRACK FORECAST.
   C. IN THE EXTENDED PERIOD, TY 02S IS EXPECTED TO ACCELERATE 
NORTHEASTWARD AND COMPLETE EXTRATROPICAL TRANSITION AS IT CONTINUES 
TO MERGE WITH A MID-LATITUDE TROUGH. AS DISCUSSED ABOVE, THE SYSTEM 
WILL LIKELY MAINTAIN GALE TO STORM FORCE WIND SPEEDS AS IT COMPLETES 
EXTRATROPICAL TRANSITION WITH BAROCLINIC SUPPORT. TRACK GUIDANCE 
DIVERGES IN THE EXTENDED RANGE AS THE GFS AND GEFS ENSEMBLE MEAN 
DEPICT AN OUTLIER SCENARIO OF A WEAKENED SYSTEM REMAINING SEPARATE 
FROM THE MID-LATITUDE WESTERLY FLOW PATTERN, WHILE THE OTHER 
AVAILABLE GUIDANCE DEPICTS DIFFERING RATES OF PRONOUNCED 
ACCELERATION INTO THE MID-LATITUDE WESTERLIES. THE CURRENT FORECAST 
FAVORS THE MAJORITY DEPICTION OF RAPID ACCELERATION AND LIES CLOSE 
TO BOTH THE MULTI-MODEL CONSENSUS AND PREVIOUS JTWC TRACK FORECASTS 
WITH MEDIUM CONFIDENCE.//
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