Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 714 PM EDT Fri Jul 24 2020 Valid 12Z Tue Jul 28 2020 - 12Z Sat Aug 01 2020 ...Overview and Guidance Evaluation... Models and ensembles offer greater than normal forecast spread and uncertainty for Alaskan and vicinity days 4-8. Continuity with individual runs is not stellar either, but guidance does tend to offer a reasonably similar larger scale pattern evolution. Accordingly, the WPC Alaskan medium range product suite was primarily derived from a blend of the 12 UTC GFS/ECMWF and GEFS/ECMWF ensemble means along with the 19 UTC National Blend of Models (NBM). Applied most weight to the ensemble means and NBM throughout the period to maintain max WPC continuity and to smooth out the less predictable small-mid scale features. This was coordinated with Alaskan offices and the resultant product still highlights several organized weather features noted below. ...Weather Highlights/Threats... Deep layered Arctic low passage should hold a frontal zone down over northern Alaska for much of next week. Frontal wave progression from the west will favor enhanced moisture and precipitation for the Brooks Range and vicinity into Tue, with unsettled conditions likely to linger but moderate later next week. Deepened North Pacific to Aleutians/Southern Bering Sea low progression will focus rainfall and waves/winds across the region next week. Lead low energies with ample closed upper low/trough support in an amplified pattern Tue-Thu will tend to transfer into an unsettled Gulf of Alaska Thu-next Sat. Upstream flow seems sufficiently amplified and favorable to bring new low pressure systems back into the Aleutians and Bering Sea into Thu-next Sat, but predictability at these longer time frames is low. 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 rain across portions of the Brooks Range and interior southeastern Alaska, Mon-Tue, Jul 27-Jul 28. 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