WDPN31 PGTW 152100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 02W (SURIGAE) WARNING 
NR 010//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
    TYPHOON (TY) 02W (SURIGAE), LOCATED APPROXIMATELY 42 NM 
NORTHEAST OF KAYANGEL, HAS TRACKED WEST-SOUTHWESTWARD AT 05 KNOTS 
OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE 
IMAGERY SHOWS CENTRAL COLD COVER CONTINUES TO BUILD UP DIRECTLY OVER 
THE LOW-LEVEL CIRCULATION CENTER (LLCC), COMPLETELY OBSCURING THE 
POSITION OF THE LLCC. THE INITIAL POSITION IS PLACED WITH GOOD 
CONFIDENCE BASED ON A 151659Z AMSR2 37GHZ IMAGE THAT REVEALS A CLEAR 
MICROWAVE EYE. THE INITIAL INTENSITY OF 65 KNOTS IS BASED ON THE 
DVORAK CURRENT INTENSITY ESTIMATES OF T4.0 (65 KNOTS) BY PGTW, RJTD 
AND KNES AND AN ADVANCED DVORAK TECHNIQUE ESTIMATE OF 65 KNOTS. 
ENVIRONMENTAL ANALYSIS INDICATES AN OVERALL FAVORABLE ENVIRONMENT 
FOR DEVELOPMENT WITH LOW (10-15KT) VERTICAL WIND SHEAR (VWS), 
DESPITE 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 IMPROVES THE OVERALL 
ENVIRONMENT FOR DEVELOPMENT. TY 02W IS CURRENTLY MOVING VERY SLOWLY, 
TRACKING ALONG THE SOUTHERN PERIPHERY OF AN EXTENSION OF THE DEEP 
LAYER SUBTROPICAL RIDGE (STR) TO THE NORTH.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE 
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TY 02W IS FORECAST TO GRADUALLY TRANSITION TO A NORTHWESTWARD 
TRACK AS A MIDLATITUDE TROUGH DIGS IN, BREAKING THE EXTENSION OF THE 
STR, ALLOWING TY 02W TO TRACK TOWARD THIS WEAKNESS IN THE STR. THE 
SYSTEM WILL STEADILY INTENSIFY AS THE PRESSURE ON THE EASTERN SIDE 
GRADUALLY SUBSIDES, LEADING TO ROBUST, DUAL CHANNEL OUTFLOW THAT 
WILL SIGNIFICANTLY IMPROVE THE ENVIRONMENT FOR DEVELOPMENT, WITH TY 
02W REACHING 95KTS BY TAU 48 AND 115KTS BY TAU 72. NUMERICAL MODEL 
GUIDANCE HAS SPREAD SLIGHTLY OVER THE PAST SIX HOURS WITH A CROSS-
TRACK SPREAD OF 180NM AT TAU 72 WITH ECMWF AND ECMWF ENSEMBLE MEAN 
FURTHER WEST BEFORE RECURVING AND JGSM RECURVING MORE ABRUPTLY. THE 
JTWC TRACK HAS BEEN PLACED NEAR THE MULTI-MODEL CONSENSUS. THERE IS 
FAIR CONFIDENCE IN THE EARLY PORTION OF THE JTWC TRACK FORECAST DUE 
TO ITS UNEXPECTED RECENT DIP OFF OF GUIDANCE TO THE SOUTHWEST.
   C. AFTER TAU 72, THE BREAK IN THE STR RESULTS IN THE STR TO THE 
EAST TAKING OVER AS THE PRIMARY STEERING MECHANISM, SENDING TY 
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 AND SEA 
SURFACE TEMPERATURES LOWER THROUGH THE END OF THE FORECAST PERIOD. 
THE SYSTEM WILL DECREASE DOWN TO 100KTS BY TAU 120. NUMERICAL MODEL 
CROSS-TRACK SPREAD IS 290NM 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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