Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 403 PM EDT Sat May 18 2019 Valid 12Z Wed May 22 2019 - 12Z Sun May 26 2019 Models continue to present chaotic and disparate solutions in terms of the pattern across Alaska during the extended forecast period. A broad upper-level mean trough is expected to be in place on Wed near/south of the Aleutians, with shortwave energy traversing southwesterly flow on the east side of the trough into the Gulf of Alaska and a mainland Alaska. Timing differences exist even early in the period with respect to these smaller-scale waves. Through time, differences only amplify. Major differences emerge by the middle of next week as to whether upper riding builds north across the Gulf toward mainland Alaska, or remains weaker allowing mid/upper-level height falls to slide east toward the Gulf. Most deterministic models have waffled between the two scenarios, while ensemble means seem to provide at least marginally consistent support for keeping a somewhat stronger ridge (which is also consistent with forecast continuity). Given low confidence and the high degree of run-to-run variability, opted to stick close to continuity, incorporating the 12Z FV3 and 06Z GFS along with ECENS/GEFS ensemble means. Ensembles comprised a majority of the forecast blend starting on day 5 (Thu), with gradually increased weight through time. 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 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