Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 729 PM EDT Thu Jul 30 2020 Valid 12Z Mon Aug 03 2020 - 12Z Fri Aug 07 2020 ...Guidance Evaluation... The WPC Alaskan medium range product suite was mainly derived from a composite blend of well clustered guidance from the 12 UTC GFS/ECMWF/UKMET/Canadian models day 4/Monday. This solution is also well supported by ensembles. Prefer to quickly transition to a composite of 12 UTC GEFS/NAEFS/ECMWF ensemble mean solutions and the 19 UTC National Blend of Models days 5-8 (Tuesday-next Friday) amid growing forecast spread. ...Weather Highlights/Threats and Predictability... A deep low slated to reach Bristol Bay and the Alaskan Peninsula/Southwest Alaska by Monday/ will have closed upper low/trough support and a strong model forecast signal. System energy will transfer downstream into the northern Gulf of Alaska into Tuesday/Wednesday and gradually fill, but enhanced wrapping moisture and rain should spread earnestly over the region into southern and southeast Alaska in less certain flow. Upstream in this storm track, a second low on the heels of the lead system may develop and work into the Southern Bering Sea/Aleutians by midweek. WPC progs show a relatively modest low due to uncertainty, but potential trough support aloft in this stream and any phasing with northern stream trough energy dug through the Bering Sea could favor stronger deepening. This low may progress into Bristol Bay and the Alaskan Peninsula/Southwest Alaska by next Thursday, then emerge into the again unsettled northern Gulf of Alaska waters into next Friday. This system also offers some potential for rainfall over southern and southeast 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 rain across portions of the Alaska Panhandle and southern Alaska, Sun-Wed, Aug 2-Aug 5. 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