MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 23W (SONGDA) WARNING NR 03// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM (TS) 23W (SONGDA), LOCATED APPROXIMATELY 224 NM SOUTH-SOUTHWEST OF MINAMI TORI SHIMA, HAS TRACKED WEST-NORTHWESTWARD AT 17 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY INDICATES A CONSOLIDATING LOW-LEVEL CIRCULATION CENTER (LLCC) WITH CURVED BANDING OVER THE WESTERN SEMI-CIRCLE OF THE LLCC. A 081653Z SSMI 85GHZ IMAGE DEPICTS SPIRAL BANDING WRAPPING INTO A DEFINED CENTER, WHICH SUPPORTS THE CURRENT POSITION WITH GOOD CONFIDENCE. ANIMATED WATER VAPOR IMAGERY REVEALS IMPROVING OUTFLOW WITH ENHANCED POLEWARD OUTFLOW ASSOCIATED WITH THE TUTT TO THE NORTH. ADDITIONALLY, EQUATORWARD OUTFLOW HAS IMPROVED AS THE BROAD UPPER-LOW TO THE SOUTHWEST HAS WEAKENED. THE CURRENT INTENSITY IS ASSESSED AT 35 KNOTS BASED ON DVORAK ESTIMATES OF T2.5 (35 KNOTS) FROM BOTH KNES AND PGTW. TS 23W IS TRACKING ALONG THE SOUTHWEST PERIPHERY OF THE DEEP-LAYERED SUBTROPICAL RIDGE (STR) TO THE NORTH. 3. FORECAST REASONING. A. NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TS 23W IS FORECAST TO TRACK NORTHWESTWARD THROUGH TAU 36 THEN RE-CURVE NORTHEASTWARD AS IT ROUNDS THE WESTERN PERIPHERY OF THE STR. TS SONGDA WILL RAPIDLY INTENSIFY AFTER TAU 24 DUE TO IMPROVING POLEWARD OUTFLOW ASSOCIATED WITH AN APPROACHING MIDLATITUDE SHORTWAVE TROUGH AND IS EXPECTED TO REACH A PEAK INTENSITY OF 80 KNOTS BY TAU 48. C. AFTER TAU 72, TS SONGDA WILL BEGIN EXTRA-TROPICAL TRANSITION (ETT) AS IT BEGINS TO INTERACT WITH THE MIDLATITUDE WESTERLIES AND THE ASSOCIATED STRONG BAROCLINIC ZONE. THE SYSTEM IS EXPECTED TO WEAKEN AS IT ENCOUNTERS INCREASING VERTICAL WIND SHEAR AND ACCELERATES NORTHEASTWARD. TS 23W WILL COMPLETE ETT BY TAU 120 AS IT GAINS FRONTAL CHARACTERISTICS AND BECOMES EMBEDDED WITHIN THE MIDLATITUDE WESTERLY FLOW. NUMERICAL MODEL GUIDANCE REMAINS IN GOOD AGREEMENT, THEREFORE, THERE IS HIGH CONFIDENCE IN THE JTWC FORECAST TRACK.// NNNN NNNN