Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 728 PM EDT Fri May 1 2020 Valid 12Z Tue May 5 2020 - 12Z Sat May 9 2020 ...Expected weather pattern and model overview... There is a good signal in the medium range guidance for a Rex block pattern to develop over the north Pacific and the Alaska mainland next week, with an upper level ridge extending northwest from British Columbia and the Yukon, and a broad upper level gyre over the Gulf of Alaska with a couple of low pressure systems passing south of the region. Another ridge axis is likely to exist near the central Aleutians with an upper trough over eastern Siberia. Relatively good agreement exists between the 12Z GEFS mean and the 12Z ECENS through about Thursday, after which the GEFS becomes much stronger with the ridge developing south of the Aleutians. The CMC and its ensemble mean indicate significant placement differences with both the Aleutians ridge and Gulf low displaced to the east of the model consensus. By Thursday night and especially into Friday, the ECMWF becomes much stronger with an upper low over the western Bering Sea that has only very limited support from its ensemble mean. There was enough synoptic scale agreement through Wednesday to merit a blend of the UKMET/ECMWF/GFS and some ensemble means, and then more of the ECENS with some GEFS and previous WPC continuity for the Thursday through Saturday time period. ...Sensible Weather... Most of central and northern Alaska is expected to be dry through Wednesday with the best rainfall prospects confined to the eastern Aleutians, southeast Panhandle, and the southern third of the mainland as low pressure over the Gulf of Alaska advects moisture inland. Some lingering below average temperatures are likely from the Brooks Range northward through midweek, and potentially well above normal readings for western portions of the Interior. These warm anomalies will probably persist through the entire medium range period for central and southern portions of the state with the upper level ridge axis building in from western Canada. This will likely accelerate melting snow for many areas. By the end of next week, there may be another round of organized rainfall and high mountain snow for the Gulf Coast region, and given the potential for strong onshore flow, patchy areas of heavy rain are possible. Farther to the north, partly cloudy skies with some afternoon showers are likely for the end of the week, although many of these areas should remain dry. D. Hamrick 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 precipitation across portions of southern mainland Alaska, Thu-Fri, May 7-8. 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