MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 12W (TWELVE) WARNING NR 06// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM (TS) 12W (TWELVE), LOCATED APPROXIMATELY 270 NM NORTHEAST OF MANILA, PHILIPPINES, HAS TRACKED EASTWARD AT 05 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY SHOWS FLARING CONVECTION SURROUNDING A PARTIALLY EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC). WATER VAPOR IMAGERY SHOWS THE OUTFLOW BANDS FROM TY 01C APPROACHING TS 12W FROM THE NORTHEAST, BEGINNING THEIR INTERACTION. A 240951Z CORIOLIS MICROWAVE IMAGE SHOWS A TIGHT WELL-DEFINED LLCC WITH SHALLOW BANDING WRAPPING IN FROM THE NORTHERN PERIPHERY. UPPER LEVEL ANALYSIS INDICATES A MARGINAL ENVIRONMENT WITH MODERATE VERTICAL WIND SHEAR (VWS) AND WEAK EQUATORWARD OUTFLOW. THE INITIAL POSITION IS EXTRAPOLATED FROM THE LLCC IN THE MICROWAVE IMAGE AND SUPPORTED BY A PGTW SATELLITE FIX WITH FAIR CONFIDENCE. THE CURRENT INTENSITY IS HELD AT 40 KNOTS BASED ON PERSISTENCE AND NO SIGNIFICANT CHANGE IN THE SYSTEM'S STRUCTURE. TS 12W IS TRACKING SLOWLY EASTWARD WITHIN STRONG LOW TO MID-LEVEL WESTERLY FLOW TO THE SOUTH. 3. FORECAST REASONING. A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. THE CURRENT INTENSITY HAS BEEN INCREASED DUE TO THE AFOREMENTIONED SCATTEROMETER PASS. B. TS 12W WILL CONTINUE TO TRACK SLOWLY EAST AND THEN TURN NORTHEASTWARD AS THE EXTENSION OF THE STEERING RIDGE TO THE SOUTHEAST BUILDS IN THROUGH TAU 24. MARGINAL ENVIRONMENTAL CONDITIONS WILL PROHIBIT SIGNIFICANT DEVELOPMENT OF THE CYCLONE AS IT GAINS LATITUDE. IN ADDITION, INCREASED VWS AND SUBSIDENCE CAUSED BY THE INTERACTION WITH TY 01C WITH FURTHER DETERIORATE THE UPPER LEVEL ENVIRONMENT. THE SYSTEM WILL BEGIN TO ACCELERATE POLEWARD AS ITS TRACK IS INFLUENCED BY TY 01C PASSING TO THE NORTH. TS 12W WILL CONTINUE TO WEAKEN DUE TO THE POOR ENVIRONMENTAL FACTORS, LEADING TO ITS DISSIPATION BY THE END OF THE FORECAST PERIOD. DYNAMIC MODEL GUIDANCE IS IN FAIR AGREEMENT WITH A HIGH DEGREE OF UNCERTAINTY DUE TO TY 01C PASSING TO THE NORTH. DUE TO THE CONTINUED MODEL SPREAD, THERE IS LOW CONFIDENCE IN THE JTWC FORECAST.// NNNN NNNN