MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 23W (SONGDA) WARNING NR 07// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM (TS) 23W (SONGDA), LOCATED APPROXIMATELY 331 NM EAST OF IWO TO, HAS TRACKED NORTHWESTWARD AT 14 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS A RAPIDLY-CONSOLIDATING LOW-LEVEL CIRCULATION CENTER (LLCC) WITH TIGHTLY-CURVED DEEP CONVECTIVE BANDING WRAPPING INTO A DEFINED CENTER. A 091806Z SSMIS 37GHZ IMAGE SHOWS MULTIPLE CONVECTIVE BANDS WRAPPING INTO THE COMPACT, WELL-DEFINED CENTER, WHICH SUPPORTS THE CURRENT POSITION WITH GOOD CONFIDENCE. ANIMATED WATER VAPOR IMAGERY REVEALS NEAR-RADIAL OUTFLOW, WHICH IS FUELING THE RAPID CONSOLIDATION. RECENT DVORAK ESTIMATES OF T3.5 FROM ALL AGENCIES SUPPORT THE CURRENT INETNSITYE ESTIMATE OF 55 KNOTS. TS 23W IS TRACKING QUICKLY NORTHWESTWARD ALONG THE SOUTHWEST PERIPHERY OF THE DEEP-LAYERED SUBTROPICAL RIDGE (STR) POSITIONED TO THE NORTHEAST. 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 12 THEN RE-CURVE NORTHEASTWARD AND ACCELERATE AS IT ROUNDS THE WESTERN PERIPHERY OF THE STR. TS SONGDA WILL RAPIDLY INTENSIFY AFTER TAU 12 DUE TO IMPROVING POLEWARD OUTFLOW ASSOCIATED WITH AN APPROACHING MIDLATITUDE SHORTWAVE TROUGH AND IS EXPECTED TO REACH A PEAK INTENSITY OF 90 KNOTS BY TAU 36. 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 96 AS IT GAINS FRONTAL CHARACTERISTICS AND BECOMES EMBEDDED WITHIN THE MIDLATITUDE WESTERLY FLOW. NUMERICAL MODEL GUIDANCE REMAINS IN EXCELLENT AGREEMENT, THEREFORE, THERE IS HIGH CONFIDENCE IN THE JTWC FORECAST TRACK.// NNNN NNNN