Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 322 PM EDT Sat Jul 27 2019 Valid 12Z Wed Jul 31 2019 - 12Z Sun Aug 04 2019 It remains the case that the overall flow pattern across Alaska should be fairly progressive during the medium range period (Wed-Sun). This features an upper level low skirting the northern coast Wed-Thurs before lifting north into the Arctic, which should push a cold front through northern and central interior Alaska. Meanwhile, one shortwave crosses the Aleutians Wednesday into Thursday next week, while another trough builds into the Bering Sea later in the week and next weekend. This type of pattern would support increasing rain chances (with snow in the higher elevations) from north to south through the week across mainland Alaska, with more enhanced precipitation possible along the favorable terrain. A couple of rounds of showery activity is also likely across the Aleutians into the Peninsula as shortwave energy passes through and the more amplified trough takes shape across the Bering Sea late next week. Mean troughing over much of Alaska would support temperatures near or below normal for most of the period. In general, the guidance shows fairly good agreement days 4-5 (albeit some minor timing and amplitude differences) to warrant a majority deterministic blend for the first part of the period. After this, detail differences in the deterministic runs increase significantly, especially with respect to the deep low across northern Alaska/the Arctic and the evolution and amplification of shortwave energy entering the Gulf/north Pacific Thursday into Friday. The ensemble means show very good agreement through the entire period so increasing weightings of the means was used after day 5. This approach fits well with yesterday's forecast, as well as with continuity downstream across the CONUS. Santorelli 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