Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 723 PM EDT Sat Mar 21 2020 Valid 12Z Wed Mar 25 2020 - 12Z Sun Mar 29 2020 ...Turning colder for much of the Interior late next week... ...Overview and Guidance/Predictability Assessment... Upper ridging initially over the northeast Pacific and Aleutians Wed-Fri will shift back to the northwestern Pacific to the south of Kamchatka as troughing digs through the Interior from the north. The models and ensembles were in good agreement to start but diverge rapidly after Thursday west of 170W. This is related to a splitting upper low near 45N/153E that translates northeastward on Thursday. The 12Z GFS and most GEFS members favor the lead (initially southern) portion of the splitting upper low whereas the other guidance favor the trailing/northern upper low. The GFS takes this stronger lead low through the Bering into Bristol Bay but the other guidance push the upper low southward once the jet upstream strengthens, favoring split flow. While all guidance show lower heights west of 170W next weekend (GFS from the west, others from the north) preference continues to be with the ECMWF-led consensus which maintains some ridging into northeastern Russia, allowing heights to dig south-southeastward through the mainland on cold NW flow. Trended strongly toward the 00Z ECMWF ensemble mean which has been a tempered version of the deterministic ECMWF (and 12Z Canadian, today) with greater stability. ...Weather Highlights/Threats... Above average temperatures across the North Slope on Wednesday will give way to near average or below average temperatures through the week along and north of the Brooks Range, but turning much colder over the central/eastern Interior as a lead and secondary cold front push through. Another modest snow event is possible later in the week around Friday as the Bering system unravels into western areas coincident with the arctic frontal progression from the north. This will all move into the Gulf next weekend with increase rain/snow for the Panhandle but much drier for the mainland and even Aleutians. 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 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