Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 605 PM EDT Fri May 15 2020 Valid 12Z Tue May 19 2020 - 12Z Sat May 23 2020 ...Guidance/Predictability Assessment... The WPC medium range Alaskan product suite was mainly derived from a composite of reasonably well clustered guidance from the 12 UTC GFS/ECMWF/Canadian through next midweek along with the 19 UTC National Blend of Models, This pattern offers above average forecast predictability. The composite of these models was combined with increasingly weighted guidance over time from even better clustered guidance from the 12 UTC GEFS/ECMWF ensemble means days 6-8. This solution maintains excellent WPC continuity. ...Weather/Hazard Highlights... A main storm track will bring a series of closed upper lows/troughs and deepened surface systems along with an enhancing moisture and wrapping heavy precipitation threat from the Aleutians through the Alaskan Peninsula and Gulf of AK/southern AK. A lead low will work into the Gulf of AK into Tuesday/Wednesday, with a second deeper storm methodically on its heels from the Aleutians to the Gulf of AK Tuesday into next Saturday. This system has trended a bit slower and deeper than yesterday and that seems reasonable given upper flow amplitude. These lows will also offer a maritime wind/wave hazard from the northern Pacific/southern Bering Sea eastward with redevelopment/slow progression into the Gulf of Alaska. Farther inland, Arctic surface high pressure will linger from the North Slope to the Interior in a pattern with modest precipitation potential under less certain upper troughing, but the ECMWF has been handling the details a bit better recently. Schichtel 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 Hazards: - Heavy precipitation across portions of southern coastal areas of Alaska, Tue, May 19 and Thu, May 21. 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