MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 21W (NEOGURI) WARNING NR 023// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM 21W (NEOGURI), LOCATED APPROXIMATELY 247 NM SOUTHWEST OF YOKOSUKA, JAPAN, HAS TRACKED EAST-NORTHEASTWARD AT 12 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS AN EXPOSED, ELONGATED LOW-LEVEL CIRCULATION WITH DEEP CONVECTION SHEARED 180NM TO THE NORTHEAST. THERE IS POOR CONFIDENCE IN THE CURRENT POSITION BASED ON THE EXPOSED, RAGGED LLC IN MSI IMAGERY. A 212203Z SSMIS 91GHZ IMAGE ALSO SHOWS DEEP CONVECTION SHEARED TO THE NORTHEAST AND INCREASINGLY DISORGANIZED LOW LEVELS. THE SYSTEM IS EMBEDDED WITHIN A MIDLATITUDE SHORTWAVE TROUGH AND ITS STRUCTURE HAS CONTINUED TO DEFORM UNDER A HOSTILE ENVIRONMENT CHARACTERIZED BY STRONG (60 KNOTS) VERTICAL WIND SHEAR. OBSERVATIONS FROM THE COAST OF JAPAN REPORT 30-40 KT SUSTAINED WINDS OVER 70 NM FROM THE SYSTEM. THE CURRENT INTENSITY IS ASSESSED AT 45 KNOTS BASED ON A 212147Z SATCON OF 43 KTS AND THE OBSERVATIONS. THE SYSTEM IS ASSESSED AS EXTRATROPICAL BASED ON A 212100Z AMSU CORE TEMPERATURE CROSS SECTION SHOWING A LOW LEVEL WARM FRONTAL ANOMALY AND A COLD CORE ALOFT, AS WELL AS THE ASYMMETRIC WIND FIELD, DRY AIR FLOWING INTO THE DRY SLOT IN THE CIMSS PRECIPITABLE WATER PRODUCT, SEA SURFACE TEMPERATURES BEING UNFAVORABLE AT 24-26 DEGREES CELSIUS, AND CONVECTION SHEARED POLEWARD OF THE LOW-LEVEL CIRCULATION, ALL CHARACTERISTIC OF EXTRATROPICAL SYSTEMS. TS 21W IS ACCELERATING NORTHEASTWARD ALONG THE NORTHERN FLANK OF THE SUBTROPICAL RIDGE WITHIN THE STRONG MIDLATITUDE WESTERLY FLOW. 3. FORECAST REASONING. A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TS 21W IS FORECAST TO CONTINUE TRACKING NORTHEASTWARD THROUGH THE FORECAST PERIOD AS AN EXTRATROPICAL SYSTEM. THE SYSTEM WILL TRACK SOUTH OF TOKYO AND THEN EAST OF HONSHU MAINTAINING GALE-FORCE WINDS. MODELS ARE HAVING DIFFICULTY RESOLVING THE EXACT POSITION IN THE NEAR TERM, AS THE SYSTEM DEFORMS UNDER THE MID-LATITUDE WESTERLY JET. THE JTWC FORECAST TRACK IS PLACED AHEAD OF THE MULTIMODEL CONSENSUS, CLOSE TO THE GALWEM SOLUTION AND CARRYING FORWARD THE CURRENT OBSERVED TRACK SPEED, AS CONSENSUS IS BEING DRAGGED SLOWER BY GFS, WHICH PREDICTS A SIGNIFICANTLY SLOWER AND MORE SOUTHERN TRACK. THERE IS LOW CONFIDENCE IN THE JTWC FORECAST TRACK.// NNNN NNNN