MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 20W (HAGIBIS) WARNING NR 024// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON 20W (HAGIBIS), LOCATED APPROXIMATELY 482 NM SOUTH OF YOKOSUKA, JAPAN, HAS TRACKED NORTH-NORTHWESTWARD AT 12 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED MULTI-SPECTRAL SATELLITE IMAGERY (MSI) REVEALS A 35 NM WIDE EYE FEATURE PARTIALLY FILLED WITH LOW LEVEL CLOUDS. THE CONVECTIVE STRUCTURE IN THE INNER CORE HAS CONTINUED TO DETERIORATE OVER THE PAST 6 HOURS, SUPPORTING THE PERSISTENT WEAKENING TREND. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE EYE VISIBLE IN THE MSI LOOP AND IS SUPPORTED BY EXTRAPOLATION FROM THE 102026Z AND 102110Z SSMIS 37 GHZ MICROWAVE IMAGES. THE INITIAL INTENSITY OF 120 KNOTS IS BASED ON DVORAK INTENSITY ESTIMATES OF 6.0 BY PGTW AND RJTD AND SUPPORTED BY A RECENT SATCON ESTIMATE OF 120 KNOTS. THE INTENSITY REFLECTS THE WEAKENING TREND THAT IS EXPECTED TO PERSIST FOR THE DURATION OF THE STORM EXISTENCE. ENVIRONMENTAL ANALYSIS INDICATED LOW TO MODERATE (10-20 KNOTS) VERTICAL WIND SHEAR (VWS) OFFSET BY GOOD EQUATORWARD OUTFLOW, STRONG POLEWARD OUTFLOW ENHANCED BY A SHORTWAVE TROUGH APPROACHING FROM THE NORTHWEST, AND FAVORABLE SSTS (28-29C). HOWEVER, THE CIMSS TOTAL PRECIPITABLE WATER (TPW) LOOP CONTINUES TO SHOW DRY AIR INFILTRATING DEEPER INTO THE STORM AND BEGINNING TO WRAP TOWARD THE CENTER OF TY 20W THAT IS PARTIALLY OFFSETTING THE PREVIOUSLY STATED FAVORABLE CONDITIONS. HAGIBIS IS CURRENTLY TRACKING NORTH-NORTHWESTERLY ALONG THE WESTERN PERIPHERY OF A DEEP-LAYERED SUBTROPICAL RIDGE (STR) TO THE EAST. 3. FORECAST REASONING. A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. STEERED BY THE STR LOCATED TO THE EAST, TY HAGIBIS WILL CONTINUE ON ITS CURRENT TRACK THROUGH TAU 12. IMMEDIATELY FOLLOWING TAU 12 IT WILL TRACK AROUND THE STR AXIS AND BEGIN ACCELERATING NORTHEASTWARD ON THE POLEWARD SIDE, MAKING A QUICK LANDFALL NEAR YOKOSUKA AT ABOUT TAU 36. THE SYSTEM WILL CONTINUE TO GRADUALLY WEAKEN DUE TO INCREASING VWS, SUBSIDENCE ASSOCIATED WITH THE APPROACHING SHORTWAVE TROUGH, AND DRY AIR CONTINUING TO WRAP INTO THE CENTER OF THE SYSTEM. TY 20W WILL BEGIN INTERACTING WITH THE UPPER LEVEL JET BY TAU 36 AND BEGIN THE EXTRATROPICAL TRANSISTION (ETT). BY TAU 60 TY 20W WILL BE FULLY EXTRATROPICAL AND WILL HAVE GAINED FRONTAL CHARACTERISTICS. THE NUMERICAL MODELS ARE IN TIGHT AGREEMENT WITH A SPREAD OF ONLY 30 NM AT TAU 36, LENDING HIGH CONFIDENCE IN THE JTWC TRACK FORECAST THAT IS PLACED JUST SLIGHTLY FASTER THAN THE MULTI-MODEL CONSENSUS.// NNNN NNNN