MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 26W (MEARI) WARNING NR 09// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON (TY) 26W (MEARI), LOCATED APPROXIMATELY 493 NM SOUTH OF IWO TO, JAPAN, HAS TRACKED NORTH-NORTHEASTWARD AT 08 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS A CENTRAL DENSE OVERCAST FEATURE WITH DEEP CONVECTIVE BANDING OVER THE SOUTHERN SEMI-CIRCLE. A 041911Z SSMIS 37GHZ IMAGE SHOWS TIGHTLY- CURVED BANDING WRAPPING INTO THE LOW-LEVEL CIRCULATION CENTER (LLCC) WITH A DEFINED CENTER, WHICH SUPPORTS THE CURRENT POSITION WITH GOOD CONFIDENCE. THE CURRENT INTENSITY IS ASSESSED AT 65 KNOTS BASED ON DVORAK INTENSITY ESTIMATES OF 65 KNOTS FROM PGTW AND RJTD. UPPER- LEVEL ANALYSIS INDICATES A FAVORABLE ENVIRONMENT WITH A STRONG POLEWARD OUTFLOW CHANNEL AND LOW VERTICAL WIND SHEAR (VWS). TY 26W IS TRACKING NORTH-NORTHEASTWARD ALONG THE WESTERN PERIPHERY OF THE DEEP-LAYERED SUBTROPICAL STEERING RIDGE. 3. FORECAST REASONING. A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TY MEARI IS EXPECTED TO CONTINUE TRACKING NORTH-NORTHEASTWARD OVER THE NEXT 72 HOURS ALONG THE WESTERN PERIPHERY OF THE SUBTROPICAL RIDGE (STR). DYNAMIC GUIDANCE IS IN TIGHT AGREEMENT LENDING HIGH CONFIDENCE TO THE FORECAST TRACK. TY 26W IS EXPECTED TO INTENSIFY STEADILY THROUGH TAU 36 UNDER FAVORABLE CONDITIONS BUT SHOULD WEAKEN AFTER TAU 36 DUE TO INCREASING VWS ASSOCIATED WITH THE MIDLATITUDE WESTERLIES. NEAR TAU 48, THE SYSTEM WILL BEGIN EXTRA- TROPICAL TRANSITION (ETT) AS IT INTERACTS WITH THE STRONG BAROCLINIC ZONE AND MIDLATITUDE WESTERLIES. C. AFTER TAU 72, TY MEARI WILL BEGIN ACCELERATING NORTHEASTWARD IN RESPONSE TO A DEEPENING UPPER-LEVEL TROUGH TO THE NORTH. VWS WILL BECOME INCREASINGLY UNFAVORABLE AS THE SYSTEM BECOMES EMBEDDED WITHIN THE DEEP WESTERLY FLOW. RAPID WEAKENING OF THE SYSTEM WILL COMMENCE BETWEEN TAU 72 AND 96. TY MEARI WILL COMPLETE ETT BY TAU 96 AS IT GAINS FRONTAL CHARACTERISTICS AND BECOMES EMBEDDED WITHIN THE MIDLATITUDE WESTERLIES. DYNAMIC MODEL GUIDANCE REMAINS IN TIGHT AGREEMENT, THEREFORE, THERE IS HIGH CONFIDENCE IN THE JTWC TRACK FORECAST.// NNNN NNNN