MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 26W (FENGSHEN) WARNING NR 016// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON (TY) 26W (FENGSHEN), LOCATED APPROXIMATELY 404 NM NORTH- NORTHWEST OF ANDERSEN AFB, HAS TRACKED NORTHWESTWARD AT 14 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A 10NM EYE WITH WARMING IN THE CENTER. THE EYE IN THE MSI LOOP SUPPORTS THE INITIAL POSITION WITH GOOD CONFIDENCE. THE INITIAL INTENSITY IS ASSESSED AT 95 KNOTS, WITHIN RANGE OF DVORAK ESTIMATES OF T5.0-5.5 (90-102 KNOTS). TY 26W IS LOCATED IN AN AREA OF LOW (10-15 KNOTS) VERTICAL WIND SHEAR, WARM SEA SURFACE TEMPERATURES (28-29 DEGREES CELSIUS) AND GOOD POLEWARD UPPER LEVEL OUTFLOW. TY 26W IS TRACKING ALONG THE SOUTHWESTERN PERIPHERY OF A DEEP-LAYERED SUBTROPICAL STEERING RIDGE SITUATED TO THE NORTH. 3. FORECAST REASONING. A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TY 26W IS FORECAST TO GRADUALLY RECURVE AROUND THE WESTERN PERIPHERY OF THE BROAD STR AFTER TAU 12. LOW VERTICAL WIND SHEAR, PASSAGE OVER WARM WATER AND IMPROVING POLEWARD OUTFLOW FROM THE PASSING MIDLATITUDE TROUGH TO THE NORTH WILL LIKELY FUEL FURTHER INTENSIFICATION THROUGH TAU 12 WITH A PEAK INTENSITY OF 105 KNOTS EXPECTED AT TAU 12. AFTER TAU 12, A WEAKENING TREND WILL BEGIN AS THE SYSTEM TRANSITS UNDER UPPER-LEVEL WESTERLY WINDS AND ENCOUNTERS INCREASING VERTICAL WIND SHEAR AND DRY AIR. THE PRIMARY STEERING INFLUENCE WILL SHIFT TO A LOW-LEVEL HIGH THAT IS FORECAST TO BUILD TO THE NORTH AFTER TAU 48, STEERING THE REMNANT LOW LEVEL CIRCULATION OF TY 26W TO THE SOUTHWEST. NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT WITH THIS OVERALL SCENARIO THROUGH TAU 36 WITH A LOW CROSS-TRACK SPREAD (70NM), BUT THERE IS STILL SIGNIFICANT UNCERTAINTY IN THE SECONDARY STEERING MECHANISM, LENDING POOR CONFIDENCE TO THE INITIAL PORTION OF THE TRACK FORECAST. C. IN THE EXTENDED FORECAST PERIOD, TY 26W IS EXPECTED TO CONTINUE WEAKENING QUICKLY UNDER STRONG (40 TO 50 KNOTS) WESTERLY VERTICAL WIND SHEAR. NUMERICAL MODELS AGREE WITH THE WESTERLY TRACK WITH THE SECONDARY STEERING MECHANISM, BUT VARY IN THEIR WEAKENING TRENDS AND THE EXACT TRACK DURING THE EXTENDED PERIOD. THE JTWC FORECAST TRACK IS PLACED NEAR CONSENSUS. THERE IS LOW CONFIDENCE IN THIS PORTION OF THE JTWC FORECAST TRACK DUE TO THE COMPLEX STEERING ENVIRONMENT AND DIFFERENCES IN TIMING OF THE SOUTHWARD TURN AND ALONG-TRACK SPEED IN LATER TAUS.// NNNN NNNN