MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 23W (SONGDA) WARNING NR 09// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON 23W (SONGDA), LOCATED APPROXIMATELY 253 NM EAST OF IWO TO, HAS TRACKED NORTH-NORTHWESTWARD AT 10 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS A RAPIDLY CONSOLIDATING SYSTEM WITH DEEP CENTRAL CONVECTION AND A NEWLY FORMED 12 NM RAGGED EYE GIVING HIGH CONFIDENCE TO THE INITIAL POSITION. A 100316Z GMI 89 GHZ IMAGE SHOWS VERY SHALLOW CONVECTION IN THE BANDING FEATURES, BUT A SOLID RING OF DEEP CONVECTION AROUND THE LOW LEVEL CIRCULATION CENTER MEASURING ONLY ABOUT 50 NM IN DIAMETER. THE INITIAL INTENSITY ASSESSMENT OF 90 KNOTS IS BASED ON DVORAK ESTIMATES OF T5.0 (90 KNOTS) FROM ALL AGENCIES. UPPER-LEVEL ANALYSIS SHOWS NEAR RADIAL OUTFLOW BEING LIMITED ON THE SOUTHERN PORTION, WITH A VERY STRONG POLEWARD TAP INTO THE MIDLATITUDE WESTERLIES, AND ACCOMPANIED BY VERY LOW VERTICAL WIND SHEAR. SSTS ARE FAVORABLE NEAR 28 CELSIUS. CURRENTLY TY SONGDA IS TRACKING NORTH-NORTHWEST ALONG THE PERIPHERY OF A SUBTROPICAL RIDGE TO THE NORTHEAST, AND SLOWING SLIGHTLY AS IT APPROACHES THE RIDGE AXIS. 3. FORECAST REASONING. A. NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TY SONGDA WILL TRACK NORTHWARD AS IT ROUNDS THE CURRENT STEERING RIDGE AXIS IN THE NEXT 12 TO 24 HOURS, EVENTUALLY SHIFTING TO A NORTHEASTWARD TRACK. OUTFLOW IS EXPECTED TO IMPROVE DURING THIS TIME AS THE SYSTEM APPROACHES MIDLATITUDE WESTERLIES AND AN APPROACHING SHORTWAVE TROUGH TO THE WEST GIVING A SHORT WINDOW FOR FURTHER INTENSIFICATION, AND REACHING A PEAK INTENSITY OF 100 KNOTS. BEYOND TAU 24 TY SONGDA WILL BEGIN TO INTERACT WITH THE APPROACHING TROUGH AND WESTERLY JET AND IS EXPECTED TO BEGIN WEAKENING AS SHEAR VALUES INCREASE. BY TAU 36 TO 48 TY SONGDA WILL BEGIN TO EXHIBIT FRONTAL CHARACTERISTICS AS IT GETS ABSORBED INTO BAROCLINIC ZONE AND TRANSITIONS INTO AN EXTRATROPICAL SYSTEM. TY SONGDA IS EXPECTED TO BECOME FULLY EXTRATROPICAL BY TAU 72. DYNAMIC MODEL GUIDANCE IS STILL IN VERY GOOD AGREEMENT, LENDING HIGH CONFIDENCE TO THE FORECAST TRACK.// NNNN NNNN