Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 758 PM EDT Fri Aug 11 2023 Valid 12Z Tue Aug 15 2023 - 12Z Sat Aug 19 2023 ...General Overview... The forecast period next week will begin with a broad upper low centered over Bristol Bay that will gradually move eastward and weaken. The polar vortex may approach the Arctic coast later in the week, but the coldest weather and the core of the low should stay north of the state. The upper ridge that has persisted over the mainland is forecast to continue breaking down through the week and lead to more seasonal temperatures across the region. ...Guidance Evaluation/Preferences... The 12Z model guidance suite is in generally good agreement for the beginning of next week, but that changes going into Thursday and beyond with multiple timing and amplitude differences across the north Pacific and Gulf region, with the CMC indicating the greatest degree of differences from the ensemble means. There has also been more of a southward trend with the polar vortex over the Arctic Ocean compared to yesterday. Taking these factors into account, the fronts/pressures forecast is primarily derived from a nearly multi-deterministic model blend through Wednesday, and then reducing the use of the GFS and CMC by end of the forecast period, whilst increasing use of the ensemble means to about 50-60% by the end of the week. ...Weather/Hazards Highlights... For the middle of next week, moist southwesterly onshore flow could lead to additional rounds of rain that may be enhanced along the Southern Coast and into the terrain of the Alaska Range, with details dependent on additional weak surface lows. At this point, significant rainfall does not look to be as heavy or widespread compared to over the weekend. Another area with potentially noteworthy rainfall will be across northwestern portions of the mainland, with moist southwest flow ahead of the polar front helping to increase coverage of showers. High temperatures should mainly stay a bit cooler than normal across the southern part of the state owing to increased cloudiness and showers. Much of the Interior should be near to slightly above average for most of the week, and cooler conditions for the northwestern mainland. Hamrick 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