Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 418 PM EDT Wed Aug 21 2019 Valid 12Z Sun Aug 25 2019 - 12Z Thu Aug 29 2019 The upper-level pattern will remain relatively consistent across Alaska during the extended period, with an area of negative height anomalies south of the Aleutians and active westerlies from that region toward the Gulf of Alaska, keeping chances for precipitation relatively high across the Panhandle. Meanwhile, persistent weak ridging across eastern Russia and the Bering Sea should allow negative height anomalies to extend from the Arctic across the northern half of Alaska, with a stream of shortwaves affecting the North Slope. Began the forecast for the extended period with a 06Z GFS/00Z CMC blend days 4-5, before gradually transitioning to heavier weighting of the ensemble means during days 6-8 due to somewhat better consensus among those solutions relative to the ensembles. The GFS/CMC showed much better consensus and consistency with the ensemble means throughout the forecast period than the 00Z ECMWF, which had an outlier solution with a deep low in the Gulf of Alaska Mon-Tue (with little ensemble support). The preferred solutions also maintain a forecast relatively close to continuity, with a low pressure system approaching the Alaska Peninsula Tue-Wed, and a second low pressure system crossing the Aleutians during the Wed-Thu time frame next week. The Tue-Wed system may bring the potential for heavy rainfall to portions of southern mainland Alaska. Farther north, a cold front should sweep across the North Slope Sun-Mon with a second one arriving Wed-Thu, bringing a couple rounds of potential rain/snow. Ryan Additional 3-7 Day Hazard information can be found on the WPC medium range hazards chart at: https://www.wpc.ncep.noaa.gov/threats/threats.php - Heavy rain across southeastern Alaska, Sat-Sun, Aug 24-25. - Heavy rain across portions of the southern mainland Alaska, Wed, Aug 28. 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