MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 10W (LEKIMA) WARNING NR 09// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM (TS) 10W (LEKIMA), LOCATED APPROXIMATELY 468 NM SOUTH OF KADENA AB, HAS TRACKED NORTH-NORTHEASTWARD AT 02 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY SHOWS A CONSOLIDATING SYSTEM WITH SYMMETRIC DEEP CONVECTION AROUND THE CORE WITH AN AREA OF DEEP CONVECTION EXTENDING TO THE SOUTH AND WEST. THE INITIAL POSITION IS PLACED WITH GOOD CONFIDENCE AND IS BASED ON A 052225Z SSMIS 91GHZ MICROWAVE IMAGE, WHICH SHOWS THE DEEP CONVECTION EXTENDING TO THE SOUTH AND WEST. THE INITIAL INTENSITY ESTIMATE OF 45 KNOTS IS BASED ON DVORAK CURRENT INTENSITY (CI) ESTIMATES OF T3.0 (45 KNOTS) FROM PGTW AND RJTD. ENVIRONMENTAL ANALYSIS SHOWS THAT TS 10W IS EXPERIENCING NEUTRAL TO UNFAVORABLE (20 TO 25 KNOT) VERTICAL WIND SHEAR WHICH IS LIMITING DEVELOPMENT. TS 10W HAS A STRONG EQUATORWARD OUTFLOW CHANNEL WHILE THE POLEWARD OUTFLOW CHANNEL REMAINS CONSTRAINED BY TS 09W TO THE NORTH. SEA SURFACE TEMPERATURE IS FAVORABLE FOR DEVELOPMENT WITH TEMPERATURES GREATER THAN 31 DEGREES CELSIUS. TS 10W IS DRIFTING NORTHWESTWARD WHILE POSITIONED BETWEEN A SUBTROPICAL RIDGE (STR) TO THE NORTH AND A NEAR EQUATORIAL RIDGE (NER) TO THE SOUTH. 3. FORECAST REASONING. A. THERE IS NO CHANGE TO THE OVERALL FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. THROUGH TAU 48, TS 10W WILL TRACK NORTHWESTWARD AS THE AFOREMENTIONED RIDGES BUILD. IMPROVING VERTICAL WIND SHEAR AND FAVORABLE SEA SURFACE TEMPERATURES WILL ALLOW TS 10W TO STEADILY INCREASE IN INTENSITY, REACHING 70 KNOTS BY TAU 48. AS TS 10W TRACKS NORTHWESTWARD IT WILL MOVE AWAY FROM TD 11W AND TS 09W WHICH WILL ALLOW FOR IMPROVED UPPER LEVEL OUTFLOW. SHORTLY BEFORE TAU 72, TS 10W WILL MAKE LANDFALL IN NORTHERN TAIWAN. DYNAMIC MODEL GUIDANCE IS IN GOOD AGREEMENT, THEREFORE, THERE IS HIGH CONFIDENCE IN THIS PORTION OF THE JTWC FORECAST TRACK. C. IN THE EXTENDED FORECAST LAND INTERACTION WITH TAIWAN WILL CAUSE TS 10W TO DECREASE IN INTENSITY, REACHING 50 KNOTS BY TAU 96. ALSO BY TAU 96, THE STR TO THE NORTH WILL BECOME THE PRIMARY STEERING FEATURE AND CAUSE TS 10W TO TURN NORTHWARD. AT TAU 96, TS 10W WILL MAKE LANDFALL IN CENTRAL CHINA AND CONTINUE TO WEAKEN IN INTENSITY AS IT TRACKS NORTHWARD. DYNAMIC MODEL GUIDANCE HAS A SPREAD OF 375 NM BY TAU 120, THEREFORE, THERE IS LOW CONFIDENCE IN THIS PORTION OF THE JTWC FORECAST TRACK.// NNNN NNNN