Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 615 PM EDT Mon Jul 04 2022 Valid 12Z Fri Jul 08 2022 - 12Z Tue Jul 12 2022 ...Heavy Precipitation Threat for the Alaskan Southern Tier... ...Pattern Overview and Weather/Hazard Highlights... Expect an active weather pattern will develop for Alaska over the next week. The weather pattern into late this week will feature closed lows/troughs centered over the Arctic Ocean and southeastern Bering Sea on the periphery of a warming upper ridge from western Canada to the Alaskan mainland. Guidance has trended to transitioning more ample southeastern Bering Sea closed low/trough energies toward Southwest Alaska/Alaskan Peninsula/Kodiak Island then south-central Alaska into Friday/Saturday where sustained and deepened Gulf of Alaskan moisture feed offers a protracted threat for moderate to locally heavy/terrain enhancing precipitation. Meanwhile, ejecting impulses and moisture northward through Southwest Alaska and into the Interior on the western periphery of the slowly eroding upper ridge should meanwhile fuel local rain chances. Additional downstream system progression with the main closed low/trough position over the Gulf will tend to be inhibited by the main upper ridge, so less certain upstream flow of additional Bering Sea/Aleutians energies into the backside of this system should tend next weekend into early next week act to reform a main closed low position underneath over the west-central Gulf of Alaska. This will focus a maritime threat, but large circulation proximity and wrapping energies should also spread additional periods of moisture and precipitation onshore across southern then southeast Alaska. Meanwhile, the Arctic vortex should stay well to the north of Alaska, but later period energies/boundaries underneath have the best chance of focusing light to moderate precipitation down from the North Slope to a potentially active Interior next Sunday-Tuesday. ...Guidance/Predictability Assessment... The 12 GFS/ECMWF solutions seem best clustered with the pattern evolution aloft of the quite compatible GEFS/NAEFS/ECMWF ensemble means through medium range time scales and a reasonable composite from days 4-8 seems to also offset more evident surface system differences, partially due to less certain smaller scale upper impulse interactions over time. Some manualÂadjustments were applied to ensure Gulf of Alaskan surface lows and wind flow were not too weakened by the mean/blending process,Âconsistent with upper support and system specific uncertainties. This forecast strategy maintains good WPC product continuity from yesterday in a pattern with seemingly average to better overall predictability. Schichtel Hazards: - Heavy rain across portions of southern coastal/higher elevations of Alaska, Fri-Sun, Jul 7-Jul 10. - Heavy rain across portions of southern coastal/higher elevations of Alaska to the Alaska Panhandle, Sun-Mon, Jul 10-Jul 11. 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