Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 804 PM EDT Mon Jul 10 2023 Valid 12Z Sat Jul 15 2023 - 12Z Wed Jul 19 2023 ...Overview... A stacked low pressure system is forecast to meander around the northeastern Pacific late week into the weekend, then gradually drift closer to Southeast Alaska with time. An upper high farther to the west over the Pacific could extend some brief ridging into the Aleutians into Bristol Bay on Friday, but the ridge will likely get overtaken as energy from the Arctic/North Slope may come in while an upper low crosses Siberia into the Bering Sea into the weekend and early next week. However, ridging could build into the eastern Interior early next week for some slightly above normal temperatures there. ...Guidance Evaluation/Preferences and Predictability Assessment... Model guidance for multiple days has tended to struggle with how much energy to bring into the state from the Arctic late week. In terms of recent guidance, the 12Z GFS indicated some of the most potent energy and an eventual closed low compared to other models, but occasional various other models have been doing the same. While it still does not seem prudent to close off a low over the Interior in the forecast, at least trends have been for the energy to overcome most of the ridging. Meanwhile guidance does show that a closed low will cross Siberia late week and set up in the Bering Sea, but actually seems to have diverged even more than previous days with its timing and orientation. Even by day 5/Saturday the 06Z GFS and 12Z CMC were faster than the ensemble means while the 12Z ECMWF and GFS were slower. Meanwhile at least the GEFS and EC ensemble means were in agreement with the timing so went toward those solutions. Model spread only increases going forward with some potential for energy to cross the Alaska Peninsula into the Pacific. Given the model variations, heavily relied on the ensemble means through the period especially by the end. ...Weather/Hazards Highlights... Moist inflow ahead of the mean Bering troughing will lead to light to moderate rain totals across particularly the western Mainland and into the Alaska Peninsula late week, and spreading into much of the Mainland into next week. Rainfall amounts do not look to be too heavy, but more showery and diurnally driven, with enhanced amounts possibly over the Alaska and Brooks Ranges. Overall cooler than normal temperatures are expected across western Alaska through the period at least in terms of highs. Meanwhile Southeast Alaska should warm above average late week before a cooling trend. Ridging building into the eastern Interior from Canada should lead to some above average temperatures there, with some potential for temperatures to rise into the 80s. Tate No significant hazards are expected over Alaska during this forecast period. 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