MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 26W (MEARI) WARNING NR 11// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON (TY) 26W (MEARI), LOCATED APPROXIMATELY 441 NM SOUTH OF IWO TO, JAPAN HAS TRACKED NORTHEASTWARD AT 04 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS A NOTABLE DEEPENING IN THE CENTRAL CONVECTION OBSCURING THE LOW LEVEL CIRCULATION CENTER. THE CYCLONE HAS BECOME MORE SYMMETRIC OVER THE PAST SIX HOURS. IN RESPONSE, THE INITIAL INTENSITY HAS BEEN INCREASED TO 80 KNOTS WHICH IS SUPPORTED BY AGENCY DVORAK INTENSITY ESTIMATES RANGING FROM T4.5-T5.0 (77-90 KNOTS). THE CURRENT POSITION IS BASED ON A SMALL LOW LEVEL MICROWAVE EYE IN THE 050520Z SSMI 37GHZ MICROWAVE IMAGE. THE 85GHZ IMAGE FROM THE SAME PASS REVEALS THAT THE BULK OF DEEP CONVECTION IS LOCATED ALONG THE SOUTHERN AND WESTERN QUADRANTS. TY MEARI IS LOCATED IN A FAVORABLE ENVIRONMENT WITH A POINT SOURCE ANTI-CYCLONE OVER THE SYSTEM PRODUCING RADIAL OUTFLOW AND LOW VERTICAL WIND SHEAR (VWS). TY 26W IS TRACKING NORTH- NORTHEASTWARD ALONG THE WESTERN PERIPHERY OF THE DEEP-LAYERED SUB- TROPICAL RIDGE (STR). 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 THROUGHOUT THE FORECAST PERIOD ALONG THE WESTERN PERIPHERY OF THE STEERING STR. TY 26W IS EXPECTED TO STEADILY INTENSIFY UNDER THE FAVORABLE ENVIRONMENTAL CONDITIONS THROUGH TAU 24 BUT SHOULD WEAKEN AFTER TAU 36 DUE TO INCREASING VWS ASSOCIATED WITH AN APPROACHING MIDLATITUDE TROUGH. NEAR TAU 36, TY MEARI WILL BEGIN EXTRA-TROPICAL TRANSITION (ETT) AS IT INTERACTS WITH THE BAROCLINIC ZONE AND EMBEDS WITHIN THE MIDLATITUDE WESTERLY FLOW. VWS ASSOCIATED WITH THE STRONG WESTERLIES WILL BECOME INCREASINGLY UNFAVORABLE AS THE SYSTEM MOVES POLEWARD. RAPID WEAKENING OF THE SYSTEM IS EXPECTED TO OCCUR AFTER TAU 48. THE TYPHOON WILL GAIN FRONTAL CHARACTERISTICS AND COMPLETE ETT AS A STRONG COLD-CORE LOW BY TAU 72. DYNAMIC MODEL GUIDANCE REMAINS IN TIGHT AGREEMENT, THEREFORE, THERE IS HIGH CONFIDENCE IN THE JTWC TRACK FORECAST.// NNNN NNNN