Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 415 PM EDT Thu Sep 19 2019 Valid 12Z Mon Sep 23 2019 - 12Z Fri Sep 27 2019 Through the extended period a mean upper-level low will be positioned over the Bering Sea and during this time, multiple longwave troughs will send low pressure systems across the Aleutian chain through the Gulf of Alaska and into Southern Mainland/Southeast and western Canada. This setup will favor a wet pattern for southern portions of the Mainland and the panhandle. Weak ridging is also expected to setup over parts of western Canada/Alaska as the week progresses - this will help transition from a cool and wet pattern to a drier and near normal air mass across the northern part of the state. Model guidance and the ensemble means are in fair agreement with the synoptic pattern; however the deterministic guidance has noticeable timing/strength differences with each of the passing shortwaves. At times the CMC lagged behind consensus while the GFS was faster and deeper. This forecast package primarily used the ECENS/GEFS/NAEFS means along with some inclusion of the ECWMF and GFS; which helped mute some of these differences. Campbell 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 Hazards: - Heavy rain across portions of the Alaska Panhandle, Mon-Tue, Sep 23-Sep 24. 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