WDPN31 PGTW 151500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 02W (SURIGAE) WARNING 
NR 009//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
    TROPICAL STORM 02W (SURIGAE), LOCATED APPROXIMATELY 80 NM 
NORTHEAST OF KAYANGEL, PALAU, HAS TRACKED WESTWARD AT 06 KNOTS OVER 
THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY 
SHOWS A LARGE CONVECTIVE BUILD UP DIRECTLY OVER THE LOW-LEVEL 
CIRCULATION CENTER (LLCC) COMPLETELY OBSCURING THE POSITION OF THE 
LLCC. THE INITIAL POSITION IS PLACED WITH FAIR CONFIDENCE BASED ON A 
1509591Z SSMIS 37GHZ IMAGE THAT REVEALS A PARTIAL MICROWAVE EYE ON 
THE EASTERN EDGE OF THE SCAN, HOWEVER THIS WAS THE BEST RECENT IMAGE 
AVAILABLE TO INFORM POSITIONING. THE INITIAL INTENSITY IS 55 KTS 
BASED ON THE DVORAK CURRENT INTENSITY ESTIMATES OF T3.5 (55KTS) BY 
PGTW AND KNES AND A SATCON OF 53KTS, HEDGING BELOW THE ADT OF 3.9 
(63KTS) THAT MAY BE SLIGHTLY INFLATED BASED ON THE RECENT INCREASE 
IN CONVECTION. UPPER-LEVEL ANALYSIS INDICATES A MARGINAL TO 
FAVORABLE ENVIRONMENT FOR DEVELOPMENT IN THE SHORT-TERM WITH LOW TO 
MODERATE (10-20KT) VERTICAL WIND SHEAR (VWS) AND OUTFLOW ALOFT 
CONTAINED TO THE WESTERN SEMICIRCLE WITH PRESSURE ON THE EASTERN 
SIDE OF THE STORM. VERY WARM (29-30C) SEA SURFACE TEMPERATURE (SST) 
IN THE PHILIPPINE SEA IMPROVE THE OVERALL ENVIRONMENT FOR 
DEVELOPMENT. TS 02W IS CURRENTLY MOVING VERY SLOWLY, TRACKING ALONG 
THE SOUTHWEST PERIPHERY OF AN EXTENSION OF THE DEEP LAYER 
SUBTROPICAL RIDGE (STR) TO THE NORTHEAST.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE 
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TS 02W IS FORECAST TO TRANSITION FROM A WESTERLY TRACK TO A 
NORTHWESTWARD TRACK BY TAU 48 AS A MIDLATITUDE TROUGH DIGS IN 
BREAKING THE EXTENSION OF THE STR ALLOWING TS 02W TO TRACK TOWARD 
THIS WEAKNESS IN THE STR. THE SYSTEM WILL STEADILY INTENSIFY AS THE 
PRESSURE ON THE EASTERN SIDE SUBSIDES BETWEEN TAUS 12 AND 24 LEADING 
TO RADIAL OUTFLOW THAT WILL SIGNIFICANTLY IMPROVE THE ENVIRONMENT 
FOR DEVELOPMENT, WITH TS 02W REACHING 95KTS BY TAU 48 AND 115KTS BY 
TAU 72. NUMERICAL MODEL GUIDANCE HAS SPREAD SLIGHTLY OVER THE PAST 
SIX HOURS WITH CROSS-TRACK SPREAD OF 170NM AT TAU 72 WITH ECMWF, 
ECMWF ENSEMBLE MEAN, GFS, AND UM TRACKING FURTHER WEST BEFORE 
RECURVING AND NAVGEM, GALWEM, GFS ENSEMBLE MEAN, AND UM ENSEMBLE 
MEAN RECURVING MORE QUICKLY. THE JTWC TRACK HAS BEEN PLACED NEAR THE 
MULTI-MODEL CONSENSUS BUT HEDGED TOWARD THE FORMER ENVELOPE OF MODEL 
SOLUTIONS, THERE IS STILL HIGH CONFIDENCE IN THE EARLY PORTION OF 
THE JTWC TRACK FORECAST.
   C. AFTER TAU 72, THE BREAK IN THE STR RESULTS IN THE STR TO THE 
EAST TAKING OVER AS THE PRIMARY STEERING MECHANISM SENDING TS 
SURIGAE POLEWARD AS IT TRACKS AROUND THE WESTERN PERIPHERY OF THIS 
RIDGE. THE ENVIRONMENTAL CONDITIONS WILL BECOME SLIGHTLY LESS 
FAVORABLE AS THE AMOUNT OF UPPER-LEVEL DIVERGENCE DECREASES 
SIGNIFICANTLY THROUGH THE END OF THE FORECAST PERIOD. THE SYSTEM 
WILL DECREASE JUST SLIGHTLY TO 110KTS AT TAU 96 AND THEN TO 100KTS 
AT THE END OF THE FORECAST PERIOD. NUMERICAL MODEL CROSS-TRACK 
SPREAD IS 450NM AT TAU 120 AS THE TWO SOLUTIONS DESCRIBED ABOVE 
DIVERGE FURTHER, LENDING LOW CONFIDENCE TO THE EXTENDED PORTION OF 
THE JTWC TRACK FORECAST.//
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