MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 12W (LIONROCK) WARNING NR 36// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON 12W (LIONROCK), LOCATED APPROXIMATELY 477 NM WEST OF IWO TO, HAS TRACKED NORTHEASTWARD AT 05 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS DEEP BANDING CONVECTION WRAPPING TIGHTLY INTO A RAGGED EYE FEATURE. MICROWAVE IMAGERY FROM A 261711Z GPM PASS SHOWS THE DEEPEST CONVECTION CONFINED TO THE SOUTHERN PERIPHERY WITH A WELL-DEFINED LOW-LEVEL MICROWAVE EYE GIVING HIGH CONFIDENCE TO THE INITIAL POSITION. THE INITIAL INTENSITY IS ASSESSED AT 90 KNOTS AND IS BASED ON OBJECTIVE DVORAK ESTIMATES FROM ALL AGENCIES REPORTING THE CURRENT INTENSITY AS T5.0 (90 KNOTS). UPPER-LEVEL ANALYSIS SHOWS A TROUGH PASSING OVER JAPAN AND PROVIDING SUBSIDENCE ON THE NORTHERN PERIPHERY RESULTING IN THE WANING CONVECTION AND DROP IN INTENSITY OVER THE LAST SIX HOURS. THE EQUATORWARD OUTFLOW REMAINS FAVORABLE DUE TO THE DOMINANT NORTHEASTERLY FLOW ASSOCIATED WITH RIDGING TO THE EAST. THE PRESENCE OF THE NORTHERN TROUGH HAS SUFFICIENTLY ERODED THE DEEP-LAYERED SUBTROPICAL RIDGE OVER THE EAST CHINA SEA, AND STEERING HAS SHIFTED TO A EAST-NORTHEAST TRACK UNDER THE INFLUENCE OF THE NEAR-EQUATORIAL RIDGE BUILDING IN FROM THE SOUTH. 3. FORECAST REASONING. A. THERE IS NO CHANGE IN THE FORECAST PHILOSOPHY FROM THE PREVIOUS PROGNOSTIC REASONING MESSAGE, HOWEVER THE TRACK HAS SHIFTED MORE EASTWARD DUE TO A WEAKENING STEERING RIDGE IN THE EXTENDED FORECAST. B. IN THE NEAR FORECAST, TY12W WILL CONTINUE TO TRACK ALONG THE PERIPHERY OF THE STEERING RIDGE ON A NORTHEAST TRACK. THE INTENSITY IS FORECAST TO INCREASE SLIGHTLY BEYOND TAU 12 AS THE UPPER-LEVEL TROUGH MOVES OUT OF THE AREA REACHING A PEAK INTENSITY OF 100 KNOTS BY TAU 36. BEYOND TAU 36 TY 12W WILL ENTER A MORE STABLE ENVIRONMENT RESULTING IN A GRADUAL WEAKENING TREND BUT WILL MAINTAIN TYPHOON STRENGTH. C. IN THE EXTENDED TAUS ANOTHER MIDLATITUDE TROUGH WILL MOVE INTO THE REGION FROM THE WEST AND STEERING WILL SHIFT TO A DEEP- LAYERED RIDGE EAST OF HOKKAIDO AROUND TAU 72 TAKING THE TRACK OF 12W NORTHWESTWARD. THE APPROACHING TROUGH WILL AID IN OUTFLOW, BUT BE OFFSET BY THE RELATIVELY STABLE ENVIRONMENT, MITIGATING THE POSSIBILITY OF REINTENSIFICATION. AS THE TRACK TURNS NORTHWESTWARD TY 12W WILL BEGIN INTERACTING WITH THE TROUGH AND BEGIN TRANSITIONING TO AN EXTRATROPICAL SYSTEM BY TAU 96 COMPLETING EXTRATROPICAL TRANSITION BY TAU 120. DYNAMIC MODEL GUIDANCE IS IN GOOD AGREEMENT THROUGH TAU 48, HOWEVER, MODEL SOLUTIONS ARE SHOWING THREE SEPARATE GROUPINGS BEYOND TAU 48 AS IT TRANSITIONS TO THE NORTHEAST STEERING RIDGE AND INTERACTS WITH THE TROUGH. ECMWF AND THE JAPANESE MODELS ARE SHOWING A TIGHTER TURN TO THE NORTHEAST BEING CAPTURED BY THE TROUGH EARLIER DUE TO WELL-ESTABLISHED STEERING RIDGE. GFDN, HWRF, GFS AND ITS ENSEMBLE ARE FAVORING A MORE NORTHEAST TRACK WITH VERY WEAK TURN TO THE NORTH, AND NOT CAPTURED BY THE TROUGH DUE TO COMPLETE EROSION OF THE STEERING RIDGE. NAVGEM, COAMPS-TC, AND UKMET ARE SHOWING A SOLUTION SOMEWHERE IN- BETWEEN AS THE STEERING RIDGE IS WEAKENED, RESULTING IN A MORE EAST WARD TRACK, BUT NOT SUFFICIENTLY WEAKENED TO AVOID BEING ABSORBED INTO THE TROUGH. THE FORECAST TRACK REFLECTS THE WEAKENED STEERING RIDGE SCENARIO. DUE TO THE SPREAD IN MODEL GUIDANCE, THERE IS LOW CONFIDENCE IN THE FORECAST TRACK.// NNNN NNNN