Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 606 PM EDT Wed May 13 2020 Valid 12Z Sun May 17 2020 - 12Z Thu May 21 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/UKMET/Canadian Sunday into Monday along with the 19 UTC National Blend of Models in a pattern with above average forecast predictability. Prefer a composite blend of still well clustered guidance from the 12 UTC GEFS/ECMWF ensemble means into days 6-8 in a period with gradually growing model solution variance. This maintains excellent WPC continuity. ...Weather/Hazard Highlights... Arctic surface high pressure will produce cooled temperatures for much of the North Slope and Interior in a pattern with modest precipitation potential under weak mean upper troughing. Above normal readings will be more confined to southern/western areas of the state. An emerging storm track will meanwhile bring a series of closed upper lows/troughs and deepened surface system along with an enhancing moisture and wrapping heavy precipitation threat from the Aleutians through the Alaskan Peninsula then southern Alaska. There is a strong guidance signal in support of a lead low on this track Sunday-Tuesday, with a second storm likely on its heels Tuesday-next Thursday. These lows will also offer a maritime wind/wave hazard from the northern Pacific/southern Bering Sea onward with redevelopment into the Gulf of Alaska. 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. 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