MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 20W (TALIM) WARNING NR 26// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON 20W (TALIM), LOCATED APPROXIMATELY 193 NM WEST-NORTHWEST OF KADENA AB, HAS TRACKED NORTH-NORTHEASTWARD AT 03 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY INDICATES THAT THE LOW LEVEL CIRCULATION CENTER (LLCC) HAS STARTED TO DECOUPLE FROM THE UPPER LEVEL ROTATION. THOUGH THERE ARE HINTS OF ANOTHER EYE DEVELOPING, THE LLCC IS OFFSET TO THE SOUTH FROM THIS NEW EYE FEATURE. 142230Z SSMIS 37 GHZ AND 89 GHZ MICROWAVE IMAGERY SUPPORTS THIS PREMISE, WITH THE ASSESSED CENTERS BEING APPROXIMATELY 10 NM APART. AVAILABLE IMAGERY CONTINUES TO SHOW LITTLE IN THE WAY OF CONVECTION, WITH A WEAK BAND STARTING TO FORM AROUND THE SOUTHERN EDGE OF THE NEW EYE, BUT OTHERWISE CONFINED TO THE NORTHEAST QUADRANT. THE INITIAL POSITION IS PLACED WITH MODERATE CONFIDENCE BASED ON SATELLITE FIXES FROM PGTW AND RJTD. THE INITIAL INTENSITY IS ASSESSED AT 80 KNOTS AND IS A BLEND BETWEEN A PGTW DVORAK CURRENT INTENSITY ESTIMATE OF T5.0 (90 KNOTS), AN AUTOMATED DVORAK TECHNIQUE (ADT) OF T4.3 (73 KNOTS) AND SATCON OF 69 KNOTS AT 0000Z. TY 20W IS NOW MOVING TO THE NORTHEAST AROUND 5 KNOTS, INDICATING THAT IT HAS ROUNDED AXIS OF THE SUBTROPICAL RIDGE (STR) AND SHOULD NOW START TO ACCELERATE TOWARDS THE NORTHEAST AHEAD OF AN APPROACHING MID- LATITUDE TROUGH AND ALONG THE WESTERN PERIPHERY OF THE STR TO THE EAST. UPPER-LEVEL ANALYSIS INDICATES THE SYSTEM RESIDES IN AN OVERALL FAVORABLE ENVIRONMENT, WITH MODERATE VERTICAL WIND SHEAR (VWS), AND STRONG POLEWARD OUTFLOW. THESE FAVORABLE FACTORS ARE HOWEVER BEING OFFSET BY THE UPWELLING OF SIGNIFICANTLY COOLER WATERS AND THE LOSS OF THE EQUATORWARD OUTFLOW CHANNEL. A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TY 20W WILL BEGIN TO ACCELERATE NORTHEASTWARD AHEAD OF A DEVELOPING MID-LATITUDE TROUGH, REMAINING ON A GENERALLY NORTHEASTWARD TRACK THROUGH TAU 72. THE SYSTEM IS EXPECTED TO UNDERGO ADDITIONAL WEAKENING THROUGH TAU 12, AS IT CONTINUES TO MOVE SLOWLY OVER WATERS WHICH HAVE COOLED DUE TO UPWELLING. FROM TAU 12 TO 24, TY 20W WILL MAINTAIN INTENSITY AT 75 KNOTS, BEFORE SHEAR INCREASES BEYOND 30 KNOTS, AND WHILE TRANSITING OVER A DEEPER POOL OF WARM WATER. THROUGH TAU 48 HOWEVER, VWS WILL BEGIN TO DRASTICALLY INCREASE, LEADING TO A SLOW WEAKENING OF THE SYSTEM BEFORE IT MAKES LANDFALL OVER SOUTHERN KYUSHU BY TAU 48. AFTER LANDFALL, TY 20W WILL RAPIDLY MOVE ACROSS SOUTHERN HONSHU AND INTO THE EAST SEA OF JAPAN BY TAU 72. THE SYSTEM WILL BEGIN EXTRATROPICAL TRANSITION PRIOR TO TAU 72 AS IT ENCOUNTERS BAROCLINIC FLOW ASSOCIATED WITH A NEGATIVELY TILTED MID-LATITUDE TROUGH. NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT THROUGHOUT THIS PORTION OF THE FORECAST, LENDING HIGH CONFIDENCE TO THE JTWC OFFICIAL FORECAST TRACK THROUGH TAU 72. C. DURING THE EXTENDED FORECAST PERIOD, TY 20W WILL RAPIDLY TRANSIT NORTHEASTWARD AS IT BECOMES FULLY EMBEDDED IN THE AFOREMENTIONED MID-LATITUDE TROUGH. EXTRATROPICAL TRANSITION IS EXPECTED TO BE COMPLETE BY TAU 96. FAVORABLE BAROCLINIC SUPPORT FROM THE MID-LATITUDE TROUGH WILL ALLOW THE SYSTEM TO BECOME AN INTENSE EXTRATROPICAL LOW WITH EXTENSIVE GALE FORCE WINDS, AS REFLECTED IN THE CURRENT FORECAST. NUMERICAL MODEL GUIDANCE REMAINS IN GOOD AGREEMENT THROUGH THE EXTENDED FORECAST PERIOD, LENDING HIGH CONFIDENCE TO THE JTWC OFFICIAL FORECAST TRACK.// NNNN NNNN