WDPN32 PGTW 170300 MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 19W (SONGA) WARNING NR 10// RMKS/ 1. FOR METEOROLOGISTS. 2. 12 HOUR SUMMARY AND ANALYSIS. A. TROPICAL STORM (TS) 19W (SONCA), LOCATED APPROXIMATELY 350 NM EAST OF IWO TO, JAPAN, HAS TRACKED NORTHWESTWARD AT 15 KNOTS OVER THE PAST SIX HOURS. ANIMATED INFRARED (IR) SATELLITE IMAGERY SHOWS CONVECTIVE BANDING WRAPPING INTO A LOW LEVEL CIRCULATION CENTER. HOWEVER, A 162204Z SSMIS MICROWAVE IMAGE DEPICTS A DEEP CONVECTIVE FORMATIVE EYE. THE INITIAL POSITION IS BASED ON THE IR AND SSMIS IMAGERY. THE INITIAL INTENSITY IS BASED ON PGTW, KNES, AND RJTD DVORAK ESTIMATES RANGING FROM 45 TO 55 KNOTS. UPPER LEVEL ANALYSIS AND WATER VAPOR IMAGERY INDICATES THE TROPICAL UPPER TROPOSPHERIC TROUGH, PREVIOUSLY ALOFT, IS WEAKENING. THE WATER VAPOR IMAGERY AND SSMIS IMAGE SHOW DRY AIR WRAPPING AROUND THE WESTERN PERIPHERY INTO THE SOUTHERN PERIPHERY. THERE IS A GOOD OUTFLOW CHANNEL TO THE EAST AND SOUTH. 3. FORECAST REASONING. A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING BULLETIN. B. TS 19W IS CURRENTLY TRACKING ALONG THE SOUTHERN PERIPHERY OF A SUBTROPICAL RIDGE (STR) TO THE NORTH. THE SYSTEM IS FORECAST TO CONTINUE TURNING POLEWARD AS A MID-LATITUDE TROUGH APPROACHES AND WEAKENS THE STR. TS 19W SHOULD BEGIN ROUNDING THE RIDGE AXIS AND INTERACTING WITH THE BAROCLINIC ZONE BY TAU 48. C. TS 19W WILL FULLY TRANSITION INTO AN EXTRA-TROPICAL SYSTEM BY TAU 96. TS 19W WILL SLOWLY INTENSIFY AS OUTFLOW IMPROVES INTO THE MID-LATITUDE TROUGH AND THEN BEGIN TO WEAKEN WITH INCREASING VERTICAL WIND SHEAR AND COOLING SEA SURFACE TEMPERATURES. NUMERICAL MODEL GUIDANCE REMAINS IN EXCELLENT AGREEMENT. THEREFORE, THIS FORECAST IS IN GOOD AGREEMENT WITH MODEL CONSENSUS.// NNNN