Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 556 PM EST Sun Mar 05 2023 Valid 12Z Thu Mar 09 2023 - 12Z Mon Mar 13 2023 ...Model Guidance/Predictability Assessment... Models continue to offer less than stellar run to run continuity in a relatively benign pattern with seemingly below normal predictability. Recent runs of the GFS have been particularly sensitive to upstream data and stream interaction issues, leading to less likely solutions with some systems from short to medium range time scales. The 12 UTC ECMWF seems best supported by GEFS/ECMWF ensembles Thursday into Friday as systems work around, into and dig to the lee of an upper ridge built over the mainland. Upper ridge amplitude also seems to support ECMWF system translations during this time frame. Systems in the pattern become increasingly chaotic and varied by next weekend. The models offer traditional trouble with any potential strong ridge breakdown and retrogression, often too quick to transition. This seems to lend a mainly GEFS/ECMWF ensemble mean solution that are slower to weaken and retrograde the upper ridge than the models through these longer time frames. However given uncertainties, the WPC medium range product suite also hedged some lingering ECMWF model data to account for some greater North Slope through Interior height falls over time than evident in the ensemble means. This may have modest validity given the models are higher resolution. ...Pattern Overview and Weather/Hazard Highlights... A plume of moisture that has persisted recently within a relatively narrow zone from the eastern Aleutians northward into western/northwestern Alaska should continue to weaken into late week on the western periphery of an amplified upper ridge over mainland Alaska as uncertain low pressure waves track from south to north across the Bering Sea and into the Arctic Ocean. Snow is expected to be the main precipitation type across western to northwestern Alaska, but mixed precipitation may occur up through southern coastal areas of the Seward Peninsula. Overall, a drying trend is forecast for the precipitation-affected areas through the middle of and into late next week. However, periods of snow can be more expected to move across the North Slope/Brooks Range mid to late week with uncertain, but potentially dynamic shortwave trough energy/height fall intrusions. Unsettling energies digging to the lee of the upper ridge position and continued flow into later periods suggests that eastern Alaska and especially the Panhandle will experience temperatures much colder than normal thanks to the Arctic high pressure system centered over Yukon. This pattern is forecast to persist along with only modest precipitation opportunities. 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