Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 644 PM EDT Sat Jul 02 2022 Valid 12Z Wed Jul 06 2022 - 12Z Sun Jul 10 2022 ...Pattern Overview and Weather/Hazard Highlights... The overall medium range period weather pattern beginning next midweek should feature closed lows/troughs over the Arctic Ocean and Bering Sea, both on the periphery of a stubborn and quite warming upper ridge from western Canada through the Alaska mainland. The Arctic vortex should stay well to the north/northwest of the North Slope, but guidance has trended to bring more of the Bering Sea closed low/trough bodily across the Aleutians and the Alaskan Peninsula/Kodiak Island to south-central Alaska into Friday along with deepened Gulf moisture and a protracted threat for some moderate to locally terrain enhancing precipitation. Northward ejecting impulses and moisture through Southwest Alaska and into the Interior on the western periphery of the upper ridge should fuel multi-day local rain chances. Additional downstream system progression with the main closed low though should become increasingly inhibited by the shielding upper ridge overtop, so a less certain upstream flow of additional Bering Sea/Aleutians energies into the backside of this lead system should tend into next weekend reform a main closed low position underneath over the western Gulf of Alaska as a maritime threat. However, overall circulation proximity and wrapping energies should continue to bring periods of moisture/precipitation inland into southern and eventually southeast Alaska. ...Guidance/Predictability Assessment... This large scale pattern evolution seems decently accounted for in guidance at medium range time scales, but individual model solutions characteristically vary more significantly with embedded systems into later next week. This likely equates to a period with near normal forecast predictability. For reasonable product continuity consistent with predictability, the WPC/Alaskan collaborated medium range product suite a composite 12 UTC GFS, ECMWF, UKMET and Canadian model blend Wednesday/Thursday before transitioning Friday to a GEFS/NAEFS/ECMWF ensemble mean blend heading into next weekend. The ensemble means are in very close agreement through these longer time frames, but the individual models become increasingly unaligned. Schichtel Additional 3-7 Day Hazard Information can be found on the WPC medium range hazards outlook 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