WDPN31 PGTW 220300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 34W (MAN-YI) WARNING NR 10// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON (TY) 34W (MAN-YI), LOCATED APPROXIMATELY 260 NM SOUTHWEST OF ANDERSEN AFB, GUAM, HAS TRACKED WEST-NORTHWESTWARD AT 23 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY SHOWS THE SYSTEM CONTINUED TO EXPAND AS MORE RAIN BANDS FORMED, ESPECIALLY ALONG THE NORTHERN FLANK. THE SYSTEM ALSO MAINTAINED A WELL-DEFINED EYE, NOW AT A 10-NM DIAMETER. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE EYE FEATURE THAT LINED UP WELL WITH A MICROWAVE EYE IN THE 212336Z AMSU IMAGE. THE INITIAL INTENSITY OF 75 KNOTS IS BASED ON THE PGUA DVORAK ESTIMATE OF T4.5/77KTS. THE ENVIRONMENT IS EXCEPTIONALLY FAVORABLE WITH LOW (10-15 KNOT) RELATIVE VERTICAL WIND SHEAR (VWS), RADIAL OUTFLOW, AND WARM (29-30 CELSIUS) SEA SURFACE TEMPERATURE. TY 34W IS TRACKING ALONG THE SOUTHWESTERN PERIPHERY OF A DEEP LAYERED SUBTROPICAL RIDGE (STR) TO THE NORTHEAST. 3. FORECAST REASONING. A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TY 34W WILL TRACK GENERALLY NORTHWESTWARD UP TO TAU 36 UNDER THE STR. AFTERWARD, AN APPROACHING MID-LATITUDE TROUGH WILL CREATE A WEAKNESS IN THE STR AND SHIFT THE TRACK NORTHWARD. THE ENVIRONMENT WILL REMAIN FAVORABLE FOR INTENSIFICATION IN THE NEAR TERM, PEAKING AT 95 KNOTS AROUND TAU 24 BEFORE GRADUALLY WEAKENING TO 60 KNOTS BY TAU 72 AS VWS INCREASES. NUMERICAL GUIDANCE IS IN GOOD AGREEMENT, LENDING MODERATE CONFIDENCE IN THIS PORTION OF THE JTWC TRACK FORECAST. C. BEYOND TAU 72, TY MAN-YI WILL TURN NORTHWESTWARD THEN NORTHWARD AS THE STR BUILDS BACK TO THE NORTH AND SLIGHTLY RECEDES. MODERATE VWS, UPPER LEVEL CONVERGENCE, AND DRY AIR ENTRAINMENT ARE EXPECTED TO CAUSE SIGNIFICANT WEAKENING, BRINGING THE INTENSITY DOWN TO 40 KNOTS BY TAU 120. THERE IS A SIGNIFICANT SPREAD IN THE NUMERICAL MODEL GUIDANCE, REACHING A SPAN OF OVER 650 NM WITH JGSM ON THE EXTREME LEFT AND CTCX ON THE EXTREME RIGHT OF THE MODEL ENVELOPE. THE JTWC TRACK FORECAST LIES NEAR THE CONSENSUS TRACK WITH LOW CONFIDENCE.// NNNN