WDPN32 PGTW 041500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 10W (LINFA) WARNING NR 11// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM (TS) 10W (LINFA), LOCATED APPROXIMATELY 218 NM NORTHEAST OF MANILA, PHILIPPINES, HAS TRACKED NORTH-NORTHWESTWARD AT 08 KNOTS OVER THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY DEPICTS A PERSISTENT AREA OF DEEP CONVECTION OBSCURING THE LOW-LEVEL CIRCULATION CENTER (LLCC). A 041307Z METOP-A IMAGE INDICATES A COMPACT CORE OF WEAKLY-CURVED DEEP CONVECTION WITH THE CURRENT POSITION LOCATED ON THE NORTHEASTERN EDGE OF THE DEEP CONVECTION. OVERALL, THERE IS FAIR CONFIDENCE IN THE CURRENT POSITION. THE CURRENT INTENSITY IS ASSESSED AT 45 KNOTS BASED ON DVORAK ESTIMATES OF 45 KNOTS FROM KNES AND PGTW. UPPER-LEVEL ANALYSIS INDICATES THE SYSTEM IS IN A FAIR ENVIRONMENT WITH MODERATE (20 KNOTS) NORTHEASTERLY VERTICAL WIND SHEAR (VWS) BEING OFFSET BY EXCELLENT EQUATORWARD OUTFLOW. 3. FORECAST REASONING. A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM THE PREVIOUS PROGNOSTIC REASONING BULLETIN. B. TS 10W WILL REMAIN ON A WEST-NORTHWESTWARD TRAJECTORY THROUGH TAU 24. EXPECT MODEST INTENSIFICATION TO 55 KNOTS DUE TO FAVORABLE SEA SURFACE TEMPERATURES AND OCEAN HEAT CONTENT, PRIOR TO MAKING LANDFALL IN NORTHERN LUZON NEAR TAU 12. THE SYSTEM WILL THEN BEGIN TO WEAKEN SLIGHTLY AS IT SKIRTS THE NORTHERN COAST OF LUZON. THE SYSTEM WILL RE-EMERGE OVER WATER NEAR TAU 24 AND WILL TURN NORTHWARD TOWARDS A BREAK IN THE STEERING STR AND INTENSIFY SLIGHTLY. C. BEYOND TAU 72, TS 10W WILL CONTINUE TO SLOWLY TRACK TO THE NORTH-NORTHEAST AND SLOWLY INTENSIFY DUE TO MARGINALLY FAVORABLE ENVIRONMENTAL CONDITIONS. DYNAMIC MODEL GUIDANCE HAS A LARGE SPREAD AFTER THE SYSTEM CROSSES LUZON, WITH NAVGEM AND GFDN ERRONEOUSLY TAKING THE SYSTEM INTO THE SOUTH CHINA SEA AND THE REMAINING GUIDANCE RECURVING THE SYSTEM TO THE NORTH AT VARYING DEGREES. THIS IS DUE TO THE COMPLEX STEERING ENVIRONMENT WITH THE BREAK IN THE STR, POSSIBLE DIRECT CYCLONE INTERACTION WITH TS 09W, AND STRONG WESTERLY FLOW AT THE LOW AND MID LEVELS SOUTH OF THE SYSTEM. DUE TO THE COMPLEX ENVIRONMENT BEYOND TAU 48 AND THE POOR MODEL GUIDANCE, THERE IS LOW CONFIDENCE IN THE JTWC FORECAST TRACK.// NNNN