WDPN31 PGTW 150900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 02W (SURIGAE) WARNING 
NR 008//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
    TROPICAL STORM 02W (SURIGAE), LOCATED APPROXIMATELY 106 NM EAST-
NORTHEAST OF KAYANGEL, PALAU HAS TRACKED WESTWARD AT 03 KNOTS OVER 
THE PAST SIX HOURS. ANIMATED MULTI-SPECTRAL SATELLITE IMAGERY (MSI) 
SHOWS LOW-LEVEL BANDING WRAPPING INTO THE LOW-LEVEL CIRCULATION 
CENTER (LLCC) WITH CONVECTION BUILDING OVER THE LLCC. THE INITIAL 
POSITION IS PLACED WITH FAIR CONFIDENCE BASED ON A 150441Z AMSR2 
37GHZ IMAGE, WHICH ALSO DEPICTS THE LOW-LEVEL BANDING WRAPPING INTO 
THE LLCC AND REVEALS A MICROWAVE EYE FORMING IN THE LOWER LEVELS. 
THE INITIAL INTENSITY IS MAINTAINED AT 50 KTS BASED ON AN AVERAGE OF 
THE DVORAK CURRENT INTENSITY ESTIMATES OF T3.5 (55KTS) BY PGTW, T3.0 
(45KTS) BY RJTD AND AN ADT OF T3.3/51KTS AND SATCON OF 53KTS. UPPER-
LEVEL ANALYSIS INDICATES A MARGINAL 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 INITIALLY INTENSIFY 
SLOWLY, BUT AFTER TAU 12 IS EXPECTED TO STEADILY INTENSIFY AS THE 
PRESSURE ON THE EASTERN SIDE WILL SUBSIDE AND RADIAL OUTFLOW WILL 
SIGNIFICANTLY IMPROVE THE ENVIRONMENT FOR DEVELOPMENT, WITH TS 02W 
REACHING 90KTS BY TAU 48 AND 115KTS BY TAU 72. NUMERICAL MODELS 
CONTINUE TO BE IN GOOD AGREEMENT WITH CROSS-TRACK SPREAD OF 140NM AT 
TAU 72 LENDING HIGH CONFIDENCE TO THE EARLY PORTION OF THE JTWC 
TRACK FORECAST, WHICH LIES NEAR THE MULTI-MODEL CONSENSUS.
   C. AFTER TAU 72, THE BREAK IN THE STR LEADS TO 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 
STR. THE FAVORABLE ENVIRONMENT WILL PERSIST AND ALLOW TS 02W TO 
MAINTAIN THE PEAK INTENSITY OF 115KTS WITH POSSIBILITY OF A HIGHER 
MAXIMUM BETWEEN TAUS 72 AND 96. AFTER TAU 96 THE SYSTEM IS EXPECTED 
TO START WEAKENING AS SST DECREASE SLIGHTLY AND UPPER-LEVEL 
DIVERGENCE LESSENS. NUMERICAL MODEL CROSS-TRACK SPREAD IS 330NM AT 
TAU 120, LENDING FAIR CONFIDENCE IN THE EXTENDED PORTION OF THE JTWC 
TRACK FORECAST.//
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