Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 316 PM EDT Mon Mar 25 2019 Valid 12Z Fri Mar 29 2019 - 12Z Tue Apr 02 2019 Especially by way of ECMWF/ECMWF mean forecasts adjusting away from some suspect solutions over the past couple days, model and ensemble clustering has dramatically improved for the strong ridge/upper high (behind a shortwave that crosses the mainland on Fri) expected to build over the mainland during the weekend and persist into early next week. The favorable guidance agreement--minus the 00Z CMC that positions the ridge west of consensus--now permits including more operational model input through the period. Among the ensemble means the 00Z GEFS shows a stronger ridge than the 06Z run so preference goes to the former for GEFS input. The 00Z ECMWF mean brings the upper high a little southeast of other means by late in the period but is still close enough to other guidance to merit inclusion as part of a blend. Teleconnections relative to the upper ridge's positive height anomaly center, over southern or western mainland depending on the day, maintain support for a fairly suppressed upper weakness to the south. This is consistent with improving guidance consensus toward dry conditions over the Gulf of Alaska region. Corresponding to the upper ridge, expect strong surface high pressure to prevail over much of the mainland and extending into northwestern Canada. Flow around the high may bring a front into the Panhandle during the weekend. Details look more chaotic across the North Pacific, Aleutians, and Bering Sea. Most guidance shows an initial regime of strong flow around an upper low near Kamchatka pushing a series of waves/fronts from the western Pacific into the western Bering Sea. Then there should be a gradual elongation of upper troughing over the North Pacific along with one or more surface lows tracking south of the Aleutians. Through this entire evolution individual model runs and ensemble members show poor clustering for specifics, favoring a blended approach to reflect the more agreeable large scale evolution and some periodic embedded features. By day 8 Tue the ensemble means generally suggest that strongest low pressure over the North Pacific should track close to the western Aleutians. Today's forecast started with a blend of the 00/12Z GFS and 00Z ECMWF plus a little 00Z UKMET early in the period followed by a model/mean blend consisting of the aforementioned GFS/ECMWF runs and 40-50 percent total 00Z GEFS/ECMWF means. Rausch Bullet points from the WPC Days 3-7 Hazards chart can be found at: https://www.wpc.ncep.noaa.gov/threats/threats.php -No significant hazards for Alaska posted. 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