Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 633 PM EST Wed Nov 10 2021 Valid 12Z Sun Nov 14 2021 - 12Z Thu Nov 18 2021 ...Overview and Guidance Evaluation/Preferences... Early next week, model guidance agrees that the pattern over Alaska will be characterized by slow-moving troughing aloft extending over the central/eastern mainland and into the northeastern Pacific (including an initial closed upper low Sunday in the Gulf of Alaska), while upper ridging moves in behind. At the surface, low pressure over the Gulf of Alaska and a low tracking through the northeastern Pacific are forecast to consolidate Sunday into Monday, while a surface high is forecast to persist over the central/northern part of the mainland. Farther upstream, negatively tilted troughing and surface low pressure will move across the Bering Sea Monday-Tuesday. These features appear to be coming into somewhat better agreement in model guidance compared to previous cycles, though some track and timing differences remain, along with differences in whether or not energy splits to create two shortwaves/surface lows--GFS runs have a split by Tuesday while ECMWF runs do not. Then, there remain questions as to how that Bering Sea troughing merges with another trough stemming from a deep upper low northeast of the state around Wednesday, though regardless this should maintain the surface low in the Gulf of Alaska. Uncertainty also abounds with the possibility of additional energy coming from upstream (Kamchatka) and track of a surface low associated with it. Overall for the early part of the period, was able to use a multi-model blend of the 12Z deterministic guidance (ECMWF, GFS, CMC, and UKMET), though phased out the UKMET quickly as it seemed to get out of phase by next Monday-Tuesday. This maintained a stronger low across the Bering Sea and differences between models were phased out somewhat. With the increasing uncertainty by the latter part of the period, gradually phased in the GEFS and EC ensemble means and ended with 60% means/40% deterministic models for the blend by next Thursday/day 8. ...Weather/Hazard Highlights... Generally dry conditions are likely for most of the mainland through next week, other than a few possible snow showers. Some light to moderate precipitation is possible for the Panhandle for the early part of the week, with the best precipitation chances over southern parts of the Panhandle with the surface low in the northeastern Pacific. Then as a front tracks across the Aleutians with the Bering Sea surface low, precipitation and gusty winds could spread eastward Sunday into Tuesday. Precipitation could be enhanced by next Wednesday-Thursday for the southeastern mainland into the Panhandle, but model guidance varies with forecast amounts at this point. Below normal temperatures will be most pronounced in terms of anomalies over the southwestern mainland, and the cold temperatures (especially in terms of highs) should spread eastward into the central/eastern mainland and the Panhandle by Monday/Tuesday and persist through the week. Meanwhile, the North Slope should see above normal readings (especially for lows) through the forecast period. Tate 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