Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 212 PM EDT Mon Apr 16 2018 Valid 12Z Fri Apr 20 2018 - 12Z Tue Apr 24 2018 An upper high will meander to the northwest of Alaska during the medium range period which will allow some height falls to slide southwestward from northwestern Canada across the interior. The models/ensembles have struggled with the track/depth of this upper troughing (or closed low) but have mostly settled on a weak but not insignificant trough to head toward southwestern Alaska and mostly merge into one upper low near the AKPen. By next week, another upper low and sfc system will push through the Bering/Aleutians. The 00Z ECMWF appeared to be too aggressive with the height falls out of NW Canada and also too slow/north with a surface low approaching the central Aleutians late Friday into Saturday, resulting in a much slower forecast overall compared to its ensemble mean, the Canadian and its mean, and the GFS/GEFS. 00Z UKMET and Canadian offered a reasonable solution over the interior in between the slightly farther east GFS and farther west ECMWF, which was where the ensembles mostly converged. Thus, opted to use that cluster to start the forecast period (Friday). 12Z GFS and previous 06Z run offered good agreement with the 06Z GEFS mean and 00Z ECMWF ensemble mean with the next system through the Bering and the exiting system in the Gulf Sun/Mon which was also in line with continuity. Preferred to stay the course in line with the ensemble means for now as the GFS tends to be too quick by days 7-8. Temperatures are forecast to be below average to start the period over much of the interior north of the Alaska Range due to the incoming trough, but then rebound in time as heights rebound ahead of the next Bering upper low. Precipitation will focus mostly into coastal south central and southeastern Alaska/Panhandle with west to southwest upper flow. Fracasso