MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 18W (MALAKAS) WARNING NR 19// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON 18W (MALAKAS), LOCATED APPROXIMATELY 274 NM SOUTH- SOUTHEAST OF TAIPEI, TAIWAN, HAS TRACKED NORTHWESTWARD AT 13 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS A TIGHTLY WOUND SPIRAL SYSTEM WITH A NEWLY FORMED PINHOLE EYE IN THE LAST SIX HOURS WHICH IS ALREADY BEGINNING TO FILL. THE INITIAL POSITION IS BASED ON SATELLITE EYE FIXES FROM PGTW AND RJTD WITH GOOD CONFIDENCE. THE INITIAL INTENSITY IS ASSESSED AT 90 KNOTS AND IS BASED ON RECENT DVORAK ESTIMATES FROM PGTW AND RJTD REPORTING THE CURRENT INTENSITY AS T5.0 (90 KNOTS). THE INITIAL WIND DISTRIBUTION WAS ADJUSTED SLIGHTLY TO REFLECT DATA OBTAINED FROM A 160155Z METOP-B ASCAT IMAGE SHOWING THE EXTENT OF THE 35 AND 50 KNOT WIND RADII TO BE LESS THAN PREVIOUSLY THOUGHT. UPPER-LEVEL ANALYSIS SHOWS MODERATE RADIAL OUTFLOW AND LOW VERTICAL WIND SHEAR WITH A TUTT CELL TO THE EAST. SEA SURFACE TEMPERATURES ARE CURRENTLY VERY FAVORABLE NEAR 29 TO 30 CELSIUS. CURRENTLY TY MALAKAS IS TRACKING NORTHWESTWARD ALONG THE PERIPHERY OF A DEEP- LAYERED SUBTROPICAL RIDGE TO THE NORTHEAST. 3. FORECAST REASONING. A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. IN THE NEAR TERM FORECAST TY MALAKAS WILL CONTINUE TO TRACK NORTHWESTWARD OVER THE NEXT 24 HOURS UNDER THE INFLUENCE OF THE STEERING RIDGE. BEYOND TAU 24 THE SUBTROPICAL RIDGE WILL REORIENT AS A SHORTWAVE TROUGH MOVES IN FROM THE WEST, ENHANCING OUTFLOW. THE TRACK WILL SHIFT TO THE NORTHEAST AS TY MALAKAS ROUNDS THE RIDGE AXIS. SLIGHT INTENSIFICATION IS EXPECTED AS CONDITIONS IMPROVE, BUT WILL BEGIN A WEAKENING TREND AS THE WIND FIELD IS DISRUPTED FROM LAND INTERACTION WITH NORTHERN TAIWAN. THE WEAKENING TREND WILL CONTINUE AS STRONG WESTERLY FLOW INCREASES VERTICAL WIND SHEAR. C. IN THE EXTENDED TAUS, TY MALAKAS WILL CONTINUE NORTHEAST, GRADUALLY WEAKENING UNDER THE WESTERLY JET. SOMETIME BETWEEN TAU 96 AND 120 TY MALAKAS WILL BEGIN TO TRANSITION INTO AN EXTRATROPICAL SYSTEM. DYNAMIC MODEL GUIDANCE IS IN GOOD AGREEMENT THROUGH TAU 36 GIVING HIGH CONFIDENCE TO THIS PORTION OF THE FORECAST TRACK. HOWEVER, THERE IS DISAGREEMENT IN THE NUMERICAL SOLUTIONS IN THE SPEED AT WHICH TY MALAKAS WILL ADVANCE ALONG ITS NORTHEASTWARD TRACK, LENDING LOW CONFIDENCE TO THIS PORTION OF THE FORECAST TRACK.// NNNN NNNN