Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 231 PM EDT Sat May 25 2019 Valid 12Z Wed May 29 2019 - 12Z Sun Jun 02 2019 Deterministic and ensemble model guidance continues to have a good handle on the overall synoptic evolution over Alaska through the medium range period. The upper level pattern favors a blocking ridge in place over mainland Alaska during the beginning to middle of next week which allows for a meandering main cyclone near the central to eastern Aleutians where it gradually weakens and dissipates. This supports unsettled weather across much of the Aleutians through most of the period, with rounds of locally heavy precipitation along the immediate coast. By the middle to end of next week the ridge should begin to break down allowing troughing to expand northward and the low near the Aleutians to nudge eastward. Farther inland across central to northern Alaska, mainly showery activity and near normal to just above normal temperatures are expected. A blend of the 00z ECMWF/12z GFS/06 FV3-GFS with ensemble mean guidance (ECENS/GEFS) provided a good starting point for today for days 4-6. The deterministic runs get increasingly chaotic by days 7 and 8 mainly with respect to the details of individual shortwaves/surface lows rounding the base of the mean trough. For this reason, the blend consisted of majority ensemble mean guidance for days 7 and 8. This maintains good continuity both with yesterday's WPC Alaska forecast and with the downstream forecast over the East Pacific/CONUS. Santorelli Additional 3-7 Day Hazard information can be found on the WPC medium range hazards chart at: https://www.wpc.ncep.noaa.gov/threats/threats.php WPC medium range Alaskan products including 500mb, surface fronts/pressures progs and sensible weather grids can also be found at: https://www.wpc.ncep.noaa.gov/alaska/ak_5dayfcst500_wbg.gif https://www.wpc.ncep.noaa.gov/alaska/akmedr.shtml https://www.wpc.ncep.noaa.gov/alaska/ak_5km_gridsbody.html