WDPN31 PGTW 161500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 02W (SURIGAE) WARNING NR 013//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
    TYPHOON 02W (SURIGAE), LOCATED APPROXIMATELY 132 NM NORTHWEST OF 
KAYANGEL, PALAU, HAS TRACKED WEST-NORTHWESTWARD AT 08 KNOTS OVER THE 
PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY REVEALS 
AN EYE POPPING THROUGH THE CENTRAL CONVECTION. THE INITIAL POSITION 
IS PLACED WITH HIGH CONFIDENCE BASED ON THE 161046Z METOP-A ASCAT 
PASS THAT CLEARLY DEPICTS THE LOW LEVEL CIRCULATION CENTER (LLCC). 
ADDITIONALLY, WIND RADII HAVE BEEN ADJUSTED BASED ON THE 
AFOREMENTIONED ASCAT PASS. THE INITIAL INTENSITY IS ASSESSED AT 90 
KNOTS BASED ON THE PGTW, RJTD, AND RCTP DVORAK CURRENT INTENSITY 
ESTIMATES OF T5.0 (90 KNOTS). ENVIRONMENTAL ANALYSIS INDICATES 
FAVORABLE CONDITIONS FOR CONTINUED INTENSIFICATION WITH LOW (<15KT) 
VERTICAL WIND SHEAR (VWS), ROBUST EQUATORWARD AND IMPROVING POLEWARD 
OUTFLOW ALOFT, AND WARM (29-30C) SEA SURFACE TEMPERATURES (SST) IN 
THE PHILIPPINE SEA. TY 02W IS CURRENTLY TRACKING TOWARDS A WEAKNESS 
IN THE STEERING SUBTROPICAL RIDGE (STR) CAUSED BY AN APPROACHING MID-
LATITUDE TROUGH.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE 
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TY 02W IS FORECAST TO TRACK TO THE NORTHWEST TOWARD THIS 
WEAKNESS IN THE STR THROUGH TAU 48. BY TAU 48 THE STR TO THE EAST 
BUILDS AND TAKES OVER AS THE PRIMARY STEERING MECHANISM, CAUSING TY 
02W TO TURN NORTHWARD. THE SYSTEM WILL STEADILY INTENSIFY DUE TO 
ROBUST UPPER-LEVEL OUTFLOW AMPLIFIED BY THE MID-LATITUDE TROUGH WITH 
TY 02W REACHING PEAK INTENSITY OF 120KTS BY TAU 48. NUMERICAL MODEL 
GUIDANCE HAS DIVERGED FURTHER FROM THE PREVIOUS WARNING WITH ECMWF 
AND THE ECMWF ENSEMBLE MEAN TRACKING NORTHWESTWARD THROUGH TAU 120 
MAKING LANDFALL ON LUZON JUST PRIOR TO TAU 120. THE MOST RECENT GFS 
RUN HAS NOW TRACKED FURTHER WEST BEFORE RECURVING, WHEREAS ALL OTHER 
MODELS RECURVE MORE QUICKLY WITH JGSM, UM AND THE UM ENSEMBLE MEAN 
AS THE EASTERNMOST SOLUTIONS. THE CROSS-TRACK SPREAD HAS INCREASED 
TO 290NM AT TAU 72 LEADING TO FAIR CONFIDENCE IN THE EARLY PORTION 
OF THE JTWC FORECAST TRACK.
   C. AFTER TAU 72, TY SURIGAE CONTINUES TO TRACK NORTHWARD ALONG 
THE WESTERN PERIPHERY OF THE STR TO THE EAST. THE ENVIRONMENTAL 
CONDITIONS WILL BECOME LESS FAVORABLE AS THE AMOUNT OF UPPER-LEVEL 
DIVERGENCE DECREASES SIGNIFICANTLY BY TAU 96 CAUSING THE SYSTEM TO 
DECREASE TO 90KTS BY TAU 120. NUMERICAL MODEL CROSS-TRACK SPREAD HAS 
INCREASED TO 620NM AT TAU 120 AS TRACK SOLUTIONS DIVERGE FURTHER, 
LENDING LOW CONFIDENCE TO THE EXTENDED PORTION OF THE JTWC TRACK 
FORECAST.//
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