MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 11W (KROSA) WARNING NR 014// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON (TY) 11W (KROSA), LOCATED APPROXIMATELY 168 NM SOUTH OF IWO TO, HAS TRACKED EASTWARD AT 01 KNOT (KT) OVER THE PAST SIX HOURS. THERE IS HIGH CONFIDENCE IN THE INITIAL POSITION BASED ON A 36 NM RAGGED EYE IN ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI). ENHANCED INFRARED IMAGERY REVEALS AN AREA OF WARMER CLOUD TOP TEMPERATURES OVER ABOUT 50 PERCENT OF THE EYEWALL. THE INITIAL INTENSITY OF 90 KTS IS CONSISTENT WITH A T5.0 (90 KTS) PGTW DVORAK FIX CURRENT INTENSITY ESTIMATE. THE ENVIRONMENT IS FAIRLY SUPPORTIVE WITH EXCELLENT EQUATORWARD AND EASTWARD OUTFLOW, MODERATE (10-20 KT) VERTICAL WIND SHEAR (VWS), AND WARM (29-30 CELSIUS) SEA SURFACE TEMPERATURE BEING PARTIALLY OFFSET BY SUBSIDENCE ALONG THE NORTHERN SECTOR DUE TO AN INDUCED UPPER-LEVEL TROUGH. TY 11W IS QUASI- STATIONARY IN A COMPLEX STEERING ENVIRONMENT WITH A NEAR EQUATORIAL RIDGE (NER) TO THE SOUTH AND A SUBTROPICAL RIDGE (STR) TO THE NORTH. 3. FORECAST REASONING. A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. IN THE NEXT 72 HOURS, PRIMARY STEERING FOR TY 11W WILL GRADUALLY TRANSITION TO THE STR AND THE TRACK WILL SLOWLY SHIFT NORTHWESTWARD TOWARD JAPAN, PASSING IWO TO AROUND TAU 36. SLIGHTLY DIMINISHED OUTFLOW, WEAK ENVIRONMENTAL SUBSIDENCE, AND CONTINUED MARGINAL VWS WILL MAKE THE ENVIRONMENT SOMEWHAT UNFAVORABLE AND WEAKENING TO 70 KTS IS ANTICIPATED BY TAU 72. MODEL TRACK GUIDANCE GENERALLY AGREES WITH THE JTWC FORECAST TRACK FORECAST FOR THIS PORTION OF THE FORECAST. HOWEVER, GIVEN HIGH UNCERTAINTY WHENEVER THERE IS A TRANSITION BETWEEN STEERING MECHANISMS, THERE IS LOW CONFIDENCE IN THIS PORTION OF THE JTWC FORECAST TRACK. C. AFTER TAU 72, TY 11W WILL CONTINUE TRACKING NORTHWESTWARD UNDER THE INFLUENCE OF THE STR UNTIL TAU 96 WHEN IT SHIFTS MORE NORTHWARD AS IT BEGINS TO ROUND THE STR AXIS. THE SLIGHT INCREASE IN INTENSITY AT TAU 120, REFLECTS THE POSSIBILITY THAT IMPROVED OUTFLOW COULD OCCUR AS TY 11W ROUNDS THE STR AXIS. IN THE EXTENDED PERIOD, NAVGEM BECOMES AN OBVIOUS EASTERN OUTLIER AND THE JTWC TRACK FORECAST IS PLACED JUST WEST OF THE CONSENSUS TRACK TO OFFSET THE OUTLIER. BASED ON HIGH UNCERTAINTY IN THE NEAR TERM FORECAST, CONFIDENCE IN THE JTWC TRACK FORECAST REMAINS LOW IN THE EXTENDED PERIOD.// NNNN NNNN