Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 800 PM EDT Thu Aug 10 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 the central Aleutians that will gradually move eastward and weaken, whilst another low may develop behind it by midweek. A deep arctic low may approach the Arctic coast later in the week, but the coldest weather should stay north of the state. The upper ridge that has persisted over the mainland is forecast to break 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 mid-week with the CMC centered well to the east of the GFS/ECMWF and their respective means with the main upper low/trough axis over the Alaska Peninsula, and this causes the CMC to be out of phase with the model consensus across the Gulf region from Wednesday and beyond. Across the Arctic, the GFS is farther southeast with a strong polar vortex for the second half of the forecast period when compared to the model consensus, even the GEFS mean. However, the GFS is generally in better agreement elsewhere across the Alaska domain. Taking these factors into account, the fronts/pressures forecast is primarily derived from a nearly multi-deterministic model blend through Tuesday, and then dropping the CMC by Wednesday night and beyond and lowering the use of the GFS some, whilst increasing use of the ensemble means to about 50-60% by the end of the week. ...Weather/Hazards Highlights... For Monday into 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 possibly in 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. More scattered and lighter showers could reach farther north across the mainland, while rain chances continue across the Aleutians to the Alaska Peninsula as well given the upper low overhead. High temperatures should mainly stay a bit cooler than normal across the southern part of the state owing to increased cloudiness and showers. However, parts of the Southeast may warm to above normal as the week progresses, influenced by an upper ridge over British Columbia. Northwestern parts of the state could see warmer than normal temperatures into early next week before that ridge aloft retreats/breaks down, allowing temperatures to trend closer to normal. Hamrick Hazards: - Heavy rain across portions of the Alaska Panhandle and southern mainland Alaska, Sun, Aug 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