MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 12W (LIONROCK) WARNING NR 44// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON 12W (LIONROCK), LOCATED APPROXIMATELY 356 NM SOUTH OF YOKOSUKA, JAPAN, HAS TRACKED NORTHEASTWARD AT 17 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS TIGHT SPIRAL BANDING WRAPPING INTO A WELL DEFINED 18 NM EYE WITH DEEP CONVECTION STARTING TO WEAKEN. THE INITIAL POSITION IS BASED ON SATELLITE EYE FIXES FROM PGTW AND RGTD WITH GOOD CONFIDENCE. THE INITIAL INTENSITY IS ASSESSED AT 110 KNOTS AND IS BASED ON DROPPING DVORAK ESTIMATES FROM ALL AGENCIES WITH THE CURRENT INTENSITY STILL BEING HELD AT T6.0 (115 KNOTS). UPPER-LEVEL ANALYSIS INDICATES SIGNIFICANT DISRUPTION TO OUTFLOW OVER THE LAST SIX HOURS. THE DEEPENING TROUGH TO THE NORTHWEST IS CREATING STRONG SOUTHWESTERLY FLOW AND RESTRICTING THE EQUATORWARD CHANNEL. A TUTT CELL TO THE NORTHEAST IS FURTHER EXACERBATING THE RESTRICTED EXHAUST OVER THE SYSTEM. CURRENTLY TY 12W IS TRACKING NORTHEASTWARD ALONG THE EXTENSION OF A NEAR EQUATORIAL RIDGE (NER) TO THE SOUTHEAST. 3. FORECAST REASONING. A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. IN THE SHORT TERM FORECAST, TY 12W IS EXPECTED TO CONTINUE TO TRACK NORTHEASTWARD UNDER THE INFLUENCE OF THE NER WHILE UNDERGOING SIGNIFICANT WEAKENING IN THE NEXT 24 HOURS AS IT TRACKS INTO COOLER WATERS AND UPPER-LEVEL CONDITIONS CONTINUE TO DETERIORATE. BEYOND TAU 24, STEERING WILL BEGIN TO SHIFT TO A NORTHERN DEEP-LAYERED RIDGE ANCHORED NEAR THE KURIL ISLANDS AND TURN TY 12W ON A NORTHWESTERLY TRACK INTO THE DEEPENING TROUGH OVER JAPAN. LANDFALL IS EXPECTED OVER NORTHERN HONSHU AROUND TAU 36 SOMEWHERE NEAR SENDAI, JAPAN WITH THE INTENSITY NEAR 70 KNOTS. TY 12W IS EXPECTED TO START EXTRATROPICAL TRANSITION AFTER TAU 36 AS IT BEGINS TO INTERACT WITH BAROCLINIC ZONE WITHIN THE TROUGH. THE MOUNTAINOUS TERRAIN OF NORTHERN HONSHU WILL SIGNIFICANTLY DISRUPT THE LOW LEVEL WIND FLOW RESULTING IN SEVERELY WEAKENED SYSTEM BY TAU 48 AS IT RESURFACES OVER THE SEA OF JAPAN WITH AN INTENSITY OF APPROXIMATELY 45 KNOTS. TY 12W IS EXPECTED TO BECOME FULLY EXTRATROPICAL BY TAU 72 AS IT TRACKS INTO MANCHURIA. DYNAMIC MODEL GUIDANCE HAS COME INTO MUCH BETTER AGREEMENT OVER THE LAST TWELVE HOURS SHOWING TIGHTER GROUPING DURING THE NORTHWEST TURN AND TRANSITION INTO THE TROUGH. THE GFDN AND COAMPS-TC SOLUTIONS ARE THE FAR EASTWARD OUTLIERS SHOWING A MUCH WIDER AND SLOWER TURN WHICH DOESN'T REFLECT THE CURRENT SYNOPTIC SITUATION WELL. THE JGSM ENSEMBLE MEAN REMAINS THE FAR WESTWARD SOLUTION SHOWING A TIGHTER TURN, BUT IS NOW CLOSER TO THE REST OF THE GROUP, REFLECTING LESS VARIATION IN THE ENSEMBLE MEMBERS. THE FORECAST TRACK IS PLACED CLOSE TO THE GLOBAL MODELS, GFS, ECMFW, NAVGEM, UKMET, AND JGSM WHICH SHOW CLOSE GROUPING THROUGH TAU 48 AS IT TRACKS OVER HONSHU. THERE STILL IS A DEGREE OF UNCERTAINTY IN THE EXACT POSITION AND TIMING OF THE NORTHWESTWARD TURN, BUT DUE TO BETTER AGREEMENT OF GLOBAL SOLUTIONS THERE IS GOOD CONFIDENCE IN THE FORECAST TRACK.// NNNN NNNN