Alaska Extended Forecast Discussion National Weather Service College Park MD 620 PM EDT Wed Jun 4 2025 Valid 12Z Sun 08 Jun 2025 - 12Z Thu 12 Jun 2025 ...Another Gulf of Alaska storm to bring a heavy rainfall threat and winds to Southcentral and Southeast Alaska this weekend... ...Guidance Evaluation/Preferences... The WPC Alaskan medium range guidance suite was mainly derived from a composite blend of well clustered guidance of the 12 UTC GFS/ECMWF/UKMET/Canadian models valid for Sunday and Monday. This solution has good ensemble and machine learning guidance support and maintains good product continuity in an active pattern with above average predictability. Guidance offers reasonably similar larger scale flow evolutions into next week, but model forecast spread and uncertainty grows more rapidly with smaller scale system depictions. Accordingly, prefer to pivot to a composite of better clustered guidance of the 12 UTC GEFS/ECMWF/Canadian ensemble means for these longer time frames in overall more benign flow over the state. In this blend, applied greater weighting to the ECMWF ensemble mean that generally seems best in line with more common multi-model details. ...Weather/Hazards Highlights... A concentrated area of heavier rainfall is expected along the southern coast and into the Southeast this weekend as another upper-low/accompanying surface frontal system lifts from the northeastern Pacific into the Gulf bringing a fetch of Pacific moisture. This collaborated threat is depicted on the WPC Hazards Outlook. Some quite gusty winds are also expected, particularly for favorable gap locations around the main low. Meanwhile, expect scattered precipitation chances will continue Sunday into Monday down mainly across the west-central mainland as focused locally by a slowly southward shifting upper low. This low will gradually work from the northern to eastern Gulf of Alaska next week to support a moderately unsettled and rainy pattern from coastal Southcentral to the Southeast in replacement of the much wetter/windy lead southern stream Gulf of Alaska low. Upstream, high latitude system translations have less than stellar run to run guidance continuity, but offer a pattern for some increased precipitation chances to northwestern areas of the state next week as moisture is channeled around a building ridge into Southwest/West Alaska in the wake of the exiting weekend Interior upper low. Also, a series of uncertain Pacific systems slated to work into the Bering Sea and Aleutians will likely bring some enhanced rainfall chances in unsettled flow, with depth and detail emerging into shorter time frames to monitor. 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