Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 654 PM EST Thu Nov 10 2022 Valid 12Z Mon Nov 14 2022 - 12Z Fri Nov 18 2022 ...Overview... Early next week, an upper low well south of the Aleutians will pair with a short-lived upper trough tracking across the mainland and a ridge across the Panhandle/western Canada to create moist Pacific southerly inflow into Southcentral Alaska and into the Panhandle, yielding some potential for heavy precipitation. After that, more widespread upper ridging and a surface high are forecast to set up across the mainland to Panhandle, for quieter weather and above average temperatures as next week progresses. The exception could be across the Aleutians, which could be influenced by shortwaves/low pressure systems for some rounds of precipitation there. ...Guidance/Predictability Assessment and Preferences... Model guidance begins in reasonably good agreement at the start of the forecast period Monday, and this lasts into about day 6/Wednesday for the large scale pattern. Models indicate the upper low south of the Aleutians/AK Peninsula (around 40-50N latitude) should stay well south of the state as it slowly tracks eastward (with some south/north wobbles as well). Meanwhile a brief and weak round of troughing is forecast to trek across the mainland with fair agreement on timing/amplitude. Then a stronger shortwave and surface low pressure system are expected to track across the western Bering Sea and eastern Siberia. Some models show these features closer to the northwest mainland than others though (like the 12Z CMC taking an eastern track closer to Alaska), which affects potential for possible precipitation and gusty winds there. But at least guidance agrees that the low track will stay west of Alaska. The general pattern of ridging across much of the state looks to have good consensus. The more uncertain part of the forecast will be with a couple of lows and shortwaves/small closed lows likely south of, but possibly over, the Aleutians for midweek and beyond. The first is a low with potentially tropical origins that tracks north/northeastward toward the region but with timing/placement differences. Then another low develops farther west tracking eastward, and there are considerable differences with if/how these surface lows and their upper level components could interact by Thursday-Friday. Thus the early part of the forecast blend was able to use a multi-model blend of the 12Z deterministic models, but with a quick increase in the GEFS/EC ensemble mean components to 60-70 percent for days 7-8 given the increasing model spread. ...Sensible Weather and Potential Hazards... While the heavier precipitation amounts have phased into the short range period, lingering modest precipitation could continue across Southcentral Alaska into northern parts of the Panhandle through Monday-Tuesday given the Pacific moisture streaming in, with snow possible in higher elevations and rain near the coast. Some light precipitation is also possible into the mainland with the upper trough moving quickly through. Then the northwestern mainland could be affected with precipitation and winds around Tuesday depending on the exact track of the eastern Siberia storm system. Generally precipitation chances are forecast to increase across the Aleutians beginning midweek, but with considerable uncertainty in the details. The upper ridge pattern will lead to above average temperatures across much of the state for the period. Exceptions could be the western mainland early in the workweek and across the Panhandle later in the week. The North Slope looks to see the highest anomalies above normal, but this time of year even anomalies of 20-30+ degrees above normal would still be below the freezing mark. Tate Hazards: - Heavy precipitation across portions of the Alaska Panhandle and mainland Alaska, Sun, Nov 13. 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