Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 650 PM EDT Thu Mar 19 2020 Valid 12Z Mon Mar 23 2020 - 12Z Fri Mar 27 2020 ...Overview and Guidance/Predictability Assessment... Resilient upper ridging will continue to meander over the northeast Pacific next week, shifting between 150W-180. With an upper low forecast to slide eastward along 80N from the New Siberian Islands through the Arctic Sea toward Banks Island by midweek, a fast upper jet will move across the Interior in two phases. This may lead to a cold push of air late next week but there remains a large amount of ensemble spread by then. A blend of the 12Z deterministic models (GFS/ECMWF/UKMET/Canadian) offered a reasonable starting point for the Mon-Wed forecast south of 60N as a modest upper low lifts across the eastern Aleutians and back southeastward south of the Gulf. To the north, the GFS and UKMET were much quicker with a system through the North Slope than the Canadian/ECMWF and no appreciable trend was noted in either camp. Despite the better continuity in the ECMWF to the south, the quick flow between the upper low to the north and upper ridge to the south (in addition to upstream uncertainty) may not support a solution as slow as the ECMWF, so a blended/middle ground solution was preferred. By the end of next week, deterministic solutions became much more aggressive to lower heights across most of the mainland but given inconsistent previous runs and large ensemble spread, opted to only partially blend in some of the GFS/ECMWF/Canadian with much more of the ensembles. ...Weather Highlights/Threats... Well above average temperatures across the North Slope will give way to near average or below average temperatures through the week, especially over the eastern Interior. A warm front on Monday will bring some snow to northwestern areas (Kotzebue to Utqiagvik and points eastward) with light to modest accumulation. A more expansive area of snow is likely on Tuesday ahead of a cold front that will temporarily stall north of the Tanana Valley before then dropping southward later in the week. Much colder air will push through most of the interior, especially eastern sections, but the veracity of the cold is uncertain. The deterministic models showed, perhaps, the extreme solutions whereas a guarded/blended solution was only modestly cold. NW flow should trend most of the mainland drier as another system in the Bering moves eastward through the Aleutians next Thu/Fri. Fracasso 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 snow across portions of mainland Alaska, Sun-Mon, Mar 22-Mar 23. - Heavy snow across portions of mainland Alaska, Mon-Tue, Mar 23-Mar 24. - Much above normal temperatures across portions of mainland Alaska, Sun-Wed, Mar 22-Mar 25. 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