Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 724 PM EDT Fri Jul 15 2022 Valid 12Z Tue Jul 19 2022 - 12Z Sat Jul 23 2022 ...Overview... A persistent and anomalously deep (for this time of year) upper low will be in place near eastern Siberia through at least the middle of next week and likely meander nearby through the rest of the week, spreading a general troughing pattern across the bulk of Alaska along with cool temperatures. Rounds of energy entering the state as well as frontal systems crossing the mainland will keep a cool, cloudy, and wet pattern in place over the state through much of next week. ...Guidance/Predictability Assessment... While model guidance is quite agreeable with the existence of the upper low and the general theme of it spreading troughing across Alaska, the details are more nebulous particularly with the center of the upper low, as well as some potential for the energy to split late in the week. Models diverge with the track of the upper low around midweek and beyond, with solutions ranging from a drift westward in the GFS runs, southward in the ECMWF, and eastward in the CMC and especially the UKMET. The GEFS and EC ensemble means were more agreeable with showing a slow turn southeastward toward the western mainland, a bit farther south from yesterday's forecast, which seems like a better middle ground solution than any deterministic model. Then the CMC is the most dramatic with an energy split, indicating lows over the eastern mainland and over the Bering Sea Friday, but the 12Z GFS shows hints of this as well. Splitting energy cannot be ruled out but it is difficult to choose any particular solution like that at this point. Overall, the WPC forecast utilized a multi-model deterministic blend early in the period, with some inclusion of the 00Z ECMWF that was not as far south as the 12Z ECMWF, but transitioned to a blend favoring the GEFS and EC ensemble means as 70 percent of the blend by the end of the period given the increasing deterministic model differences. ...Weather/Hazard Highlights... Chances for precipitation continue across the state (from the Aleutians into the Mainland and Panhandle at times) all throughout next week associated with rounds of energy aloft and frontal systems in place that could focus the moisture. Confidence in the details is low, but current forecasts show that Southcentral Alaska could see enhanced rain amounts around midweek to late week, and total rainfall will likely be highest in that area. A warm front and increasing moisture could lead to increased rainfall chances across the Aleutians late week. Precipitation may be in the form of snow in northwestern and north-central Alaska, especially in higher elevations. Given the proximity of the northern upper low spilling troughing into the state next week, expect temperatures to be well below normal in most areas, especially in terms of highs. Low temperatures are forecast to cool to below average as well Tuesday-Saturday, starting in the northwestern mainland and spreading inland across much of the mainland as the trough encroaches. Chilly lows in the 30s are possible for parts of the Brooks Range and North Slope. Tate Hazards: - Much below normal temperatures across portions of mainland Alaska, Mon-Fri, Jul 18-Jul 22. 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