WDPN31 PGTW 170900 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 02W (SURIGAE) WARNING NR 016// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUPER TYPHOON (STY) 02W (SURIGAE), LOCATED APPROXIMATELY 392 NM EAST-SOUTHEAST OF LEGAZPI, PHILIPPINES, HAS TRACKED NORTHWESTWARD AT 11 KNOTS (KTS) OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY SHOWS A HIGHLY-SYMMETRICAL SYSTEM WITH A CENTRAL DENSE OVERCAST (CDO) THAT CONTINUED TO DEEPEN WHILE MAINTAINING A SHARPLY OUTLINED 14-NM EYE. FEEDER BANDS HAVE SHORTENED AS THEY SPIRALED TIGHTER INTO THE CDO. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE OVER THE WELL-DEFINED EYE. THE INITIAL INTENSITY OF 130KTS IS BASED ON AN OVERALL ASSESSMENT OF AGENCY DVORAK ESTIMATES OF T6.0/115KTS (RCTP), T6.5/127KTS (PGTW/RJTD), T7.0/140KTS (RCTP), AND THE OBJECTIVE SATCON CONSENSUS ESTIMATE OF T7.2/146KTS THAT REFLECTS THE IMPROVED CONDITION OF THE SYSTEM. ENVIRONMENTAL ANALYSIS INDICATES ROBUST EQUATORWARD AND POLEWARD OUTFLOW, LOW (5-10 KTS) VERTICAL WIND SHEAR, AND WARM (29-30C) SEA SURFACE TEMPERATURES IN THE PHILIPPINE SEA CONTRIBUTING TO AN OVERALL FAVORABLE ENVIRONMENT FOR FURTHER DEVELOPMENT. STY 02W IS TRACKING TOWARD A BREAK IN THE SUBTROPICAL RIDGE TO THE NORTH. 3. FORECAST REASONING. A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. STY 02W WILL CONTINUE ON ITS CURRENT TRACK AND INTENSIFY THROUGH TAU 12 TO A PEAK OF 135 KTS. AFTERWARD, IT IS EXPECTED TO SLOW AS IT ENTERS A WEAK STEERING ENVIRONMENT. BY TAU 36, THE SPLIT SUBTROPICAL RIDGE (STR) TO THE NORTHEAST WILL BUILD, REORIENT AND TAKE OVER AS THE PRIMARY STEERING MECHANISM, DRIVING THE CYCLONE TO A NORTHWARD TRAJECTORY. AS IT GAINS LATITUDE, DIVERGENCE ALOFT WILL DECREASE AND CAUSE THE SYSTEM TO SLOWLY WEAKEN DOWN TO 110KTS BY TAU 72. NUMERICAL MODELS ARE IN FAIR AGREEMENT DURING THIS PORTION OF THE FORECAST WITH A GRADUAL AND EVEN CROSS-TRACK SPREAD TO 205NM BY TAU 72. THEREFORE, THERE IS FAIR CONFIDENCE IN THE EARLY PORTION OF THE JTWC FORECAST TRACK WHICH IS LAID OVER BUT SLIGHTLY SLOWER THAN THE MULTI-MODEL CONSENSUS DURING THE SLOW PROGRESSION IN THE WEAK STEERING SEGMENT. C. AFTER TAU 72, STY SURIGAE WILL CONTINUE NORTHWARD ALONG THE WESTERN PERIPHERY AND CREST THE AXIS OF THE STR. AS IT MOVES FURTHER NORTH, THE ENVIRONMENT WILL SLOWLY BECOME LESS FAVORABLE AS UPPER LEVEL DIVERGENCE CONTINUES TO DECREASE, LEADING TO GRADUAL WEAKENING DOWN TO 85 KTS BY TAU 120. NUMERICAL MODELS DIVERGE SIGNIFICANTLY TO A CROSS-TRACK SPREAD OF 415 WITH ECMF/NVGM ON THE LEFT MARGIN TO THE NORTHEASTERN TIP OF LUZON AND AEMN/UEMN ON THE RIGHT MARGIN OF THE MODEL ENVELOPE. DUE TO THE LARGE CROSS-TRACK SPREAD AMONG THE MODEL SOLUTIONS, THERE IS LOW CONFIDENCE IN THE EXTENDED PORTION OF THE JTWC TRACK FORECAST.// NNNN