Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 427 PM EST Sun Dec 04 2022 Valid 12Z Thu Dec 08 2022 - 12Z Mon Dec 12 2022 ...Guidance/Predictability Assessment and Preferences... The guidance shows broad, general agreement concerning the general flow pattern in and around AK -- a persistent upper low/trough over eastern Asia, broad ridging across the north-central Pacific and at times AK, and downstream troughing across the far northeast Pacific and western North America. The area of better model agreement remains near the AK Panhandle for a fourth day, but small issues amongst the guidance will meaningfully impact how much snow occurs in the AK Panhandle. The same is not true in the Aleutians, where the guidance continues to struggle with the depth aloft of various shortwaves/possible upper lows and their related cyclones moving through/near the area, into and possibly through the Bering Sea. Day-to-day changes in individual pieces of deterministic guidance continues to be less than ideal, arguing for a consensus/compromise approach to deal with any possible outlier solutions. There are indications that by late next weekend, amplification of the flow pattern will lead to greater predictability/more consistency/less uncertainty in the forecast. For the 500 hPa heights, pressures, fronts, and winds, generally used a deterministic heavy blend of the 12z GFS, 12z ECMWF, 12z UKMET, and 12z Canadian early on before including up to 55% of the 12z NAEFS mean/00z ECMWF ensemble means thereafter with tweaks made (lower pressures and increase winds) so that systems weren't so washed out. This idea maintained reasonable continuity with the previous few days of forecasts. The QPF used the 19z NBM and, 12z GFS, 12z Canadian, and 12z ECMWF solutions. The remainder of the grids were 19z NBM weighted, as usual. ...Weather/Hazards Highlights... With the flow pattern expected, once the troughing shifts east across AK, a drying trend should be seen across the interior and North Slope while wet conditions are expected to be constrained to the Aleutians, southern coast, and AK Panhandle (which should see a bulk of the precipitation Wednesday possibly into early Thursday). A cooling trend begins next Thursday night across the interior and and the AK Panhandle as an upper level trough departs and continues afterward due to convergence aloft between the departing upper trough and a developing upper ridge across western mainland AK leading to cold and dry surface high pressure system enveloping the interior. Whether or not the North Slope joins in on the cooling depends on detail issues in the guidance that have been inconsistent (at best) over the past few days. Cold appears to be the main story this period, with low temperatures forecast to fall as low as -30F across the normally colder eastern interior next weekend. Roth 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