WDPN31 PGTW 301500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 10W (SAOLA) WARNING NR 11// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON (TY) 10W (SAOLA), LOCATED APPROXIMATELY 320 NM SOUTH-SOUTHEAST OF TAIPEI, TAIWAN, HAS TRACKED NORTH-NORTHWESTWARD AT 05 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY SHOWS THE SYSTEM HAS MAINTAINED A RAGGED EYE AND TIGHT CONVECTIVE BANDING INTO THE EYE. THERE IS HIGH CONFIDENCE IN THE INITIAL POSITION AS THE EYE FEATURE IS ALSO EVIDENT ON A 301110Z SSMIS MICROWAVE IMAGE. THE INITIAL INTENSITY OF 65 KNOTS IS SUPPORTED BY AN OBJECTIVE DVORAK ESTIMATE FROM CIMS BUT IS HIGHER THAN SUBJECTIVE DVORAK ESTIMATES OF 55 KNOTS FROM PGTW AND RJTD. THERE IS, HOWEVER, HIGH CONFIDENCE IN THE INTENSITY DUE TO THE PRESENCE OF THE EYE FEATURE. UPPER LEVEL ANALYSIS REVEALS THE CYCLONE IS BETWEEN TWO RIDGE AXES - ONE TO THE NORTH AND ONE TO THE SOUTH - IN AN AREA OF LIGHT (05-10 KNOT) VERTICAL WIND SHEAR (VWS). IT IS IN A WEAK STEERING STEERING ENVIRONMENT BETWEEN A SLIGHTLY MORE PREDOMINANT NEAR EQUATORIAL RIDGE (NER) TO THE EAST-SOUTHEAST AND A SUBTROPICAL RIDGE (STR) TO THE NORTH. 3. FORECAST REASONING. A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM THE PREVIOUS PROGNOSTIC REASONING. B. TY 10W IS FORECAST TO CONTINUE ALONG ITS CURRENT TRACK THROUGH TAU 72 UNDER THE STEERING INFLUENCE OF THE AFOREMENTIONED NER. DYNAMIC MODEL GUIDANCE REMAINS IN FAIR AGREEMENT WITH EGRR AS THE SOLE OUTLIER TO THE RIGHT OF THE MODEL ENVELOPE. THE SYSTEM IS EXPECTED TO PEAK AT 105 KNOTS BY TAU 48 DUE TO THE FAVORABLE ENVIRONMENT, ESPECIALLY THE ROBUST RADIAL OUTFLOW. BY TAU 72, THE SYSTEM IS EXPECTED TO START WEAKENING AS VWS INCREASES AS THE STR TO THE NORTHEAST BUILDS AND ASSUMES STEERING. C. IN THE EXTENDED TAUS, TY 10W WILL TURN WESTWARD AS THE STR BECOMES THE DOMINANT STEERING MECHANISM. DURING THIS TIME FRAME, TS 11W, CURRENTLY LOCATED 195 NM EAST-NORTHEAST OF IWO-TO, JAPAN, WILL APPROACH AT ITS CLOSEST POINT BUT WILL HAVE MINIMAL IMPACT ON 10W. THERE IS LOW OVERALL CONFIDENCE IN THE FORECAST TRACK DUE TO THE WEAK STEERING ENVIRONMENT THROUGH TAU 72 AND POSSIBLE WEAK INTERACTION WITH 11W. AFTER TAU 72, THERE IS INCREASED CONFIDENCE IN THE FORECAST TRACK AS THE STEERING INFLUENCE TRANSITIONS TO THE STRONG STR. // NNNN