Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 730 PM EDT Sat Aug 5 2023 Valid 12Z Wed Aug 9 2023 - 12Z Sun Aug 13 2023 ...Synoptic Overview... A large upper level gyre is expected to be in place across the northern Bering Sea for the middle of next week, and an upper level trough with embedded shortwaves across the Gulf region. The upper ridge axis over far northwestern Canada is forecast to slowly break down some going into next weekend, but should remain across the Yukon and Northwest Territories. The main Bering low should gradually drop south toward the Aleutians and a shortwave pivoting around it should spur surface cyclogenesis south of the Alaska Peninsula with the surface low lifting northeastward and bringing more widespread rain for south-central portions of the state and also extending across the southeast Panhandle region. ...Guidance Evaluation/Preferences and Predictability Assessment... Models and ensembles for the 12Z model cycle are in good overall synoptic scale agreement across the Alaska domain for the middle of the week, with some minor timing differences with shortwave energy crossing the Gulf of Alaska. Looking ahead to the end of the week, the deterministic guidance is indicating an intensifying surface low south of the Aleutians, with the CMC the strongest solution like yesterday, and the GFS now more in line with the CMC/ECMWF compared to yesterday. The greatest degree of model spread exists over the Gulf region and northwestern Canada by the second half of the forecast period, and the best agreement over western portions of Alaska. Taking these factors into account, the WPC front/pressures forecast is primarily derived from a nearly multi-deterministic model blend through Thursday, and then increasing use of the ensemble means to about 40% by next Sunday. ...Weather/Hazards Highlights... The high latitude upper ridge over the northeastern mainland into the Yukon will continue to support above normal temperatures, but slightly cooler than what is expected in the short range forecast period. Daytime highs may reach the lower to middle 80s over parts of the Yukon Flats, while the North Slope could see readings rise into the 70s away from the coast. Highs should mainly in the 60s and 70s across most of the mainland by next weekend. Low temperatures should generally be above normal across most of the state with the greatest anomalies over the North Slope, especially early on. In terms of precipitation, onshore flow across the southern mainland coastal areas and also the Alaska Peninsula will favor rounds of moderate to occasionally heavy rainfall, with some localized totals of 2-4 inches possible across the windward terrain near the coast. This will also hold true for portions of the southeast Panhandle. The greatest prospects for heavier rain near the coast will be Friday night through Saturday as the next organized storm system approaches. 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