MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 30W (NOCK-TEN) WARNING NR 23// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON (TY) 30W (NOCK-TEN), LOCATED APPROXIMATELY 215 NM WEST OF MANILA, PHILIPPINES, HAS TRACKED WEST-NORTHWESTWARD AT 12 KNOTS OVER THE PAST SIX HOURS. AFTER A BRIEF PERIOD OF RE-ORGANIZATION, ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY INDICATES THAT CONVECTION IS ONCE AGAIN BECOMING RAGGED AND ASYMMETRIC, PARTICULARLY ALONG THE NORTHERN PERIPHERY. THE EIR ALSO INDICATES THAT LOW LEVEL CLOUDS ARE NOW BUILDING TO THE SOUTHWEST. IN THE ABSENCE OF RECENT MICROWAVE IMAGERY, THE INITIAL POSITION IS BASED ON PGTW AND RJTD FIXES WITH FAIR CONFIDENCE. THE INITIAL INTENSITY IS REDUCED TO 65 KNOTS BASED ON PGTW AND RJTD DVORAK T4.0 (65 KNOTS) ESTIMATES. UPPER-LEVEL ANALYSIS INDICATES THAT TY 30W IS NEARLY UNDERNEATH THE SUBTROPICAL RIDGE (STR) AXIS, WITH GOOD POLEWARD OUTFLOW PARTIALLY OFFSETTING INCREASING VERTICAL WIND SHEAR (VWS). THE CYCLONE CONTINUES TO TRACK WEST-NORTHWESTWARD ALONG THE SOUTHWESTERN PERIPHERY OF A DEEP-LAYERED STR WHICH REMAINS ENTRENCHED TO THE NORTH OF THE SYSTEM. 3. FORECAST REASONING. A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TY NOCK-TEN IS FORECAST TO CONTINUE TRACKING WEST- NORTHWESTWARD OVER THE NEXT 6-12 HOURS UNDER THE STEERING INFLUENCE OF THE STR, AFTER WHICH THE LLCC WILL BECOME FULLY EMBEDDED IN NORTHEASTERLY FLOW ASSOCIATED WITH A COLD SURGE EVENT AND TURN SHARPLY SOUTHWESTWARD. AT THAT TIME, DEEP CONVECTION WILL BECOME DECOUPLED AND MOVE OFF TO THE NORTH-NORTHEAST, FOLLOWING THE MID- TO UPPER-LEVEL FLOW. PRIOR TO THE SOUTHWESTWARD TURN, FAVORABLE UPPER LEVEL DIFFLUENCE WILL RESULT IN GRADUAL WEAKENING, AFTER WHICH HIGH (25-30 KNOT) VWS AND THE CONVECTIVE DECOUPLING WILL RESULT IN RAPID WEAKENING. THE FORECAST CALLS FOR DISSIPATION BY TAU 48, HOWEVER, ANALYSIS OF LOW LEVEL MODEL VORTICITY FIELDS SUGGESTS DISSIPATION MAY OCCUR EVEN SOONER. DYNAMICAL MODEL GUIDANCE IS IN GOOD AGREEMENT THROUGHOUT THE FORECAST PERIOD. THE JTWC FORECAST TRACK IS POSITIONED CLOSE TO THE MULTI-MODEL CONSENSUS AND REMAINS CONSISTENT WITH PREVIOUS FORECASTS, LEADING TO HIGH CONFIDENCE IN THE JTWC FORECAST TRACK.// NNNN NNNN