Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 548 PM EST Wed Feb 05 2020 Valid 12Z Sun Feb 09 2020 - 12Z Thu Feb 13 2020 Models/ensembles show general consensus that an upper-level ridge axis across the North Pacific will gradually build northward across Alaska through the extended forecast period, perhaps weakening to some degree by the middle of next week in response to strong incoming shortwave energy in the westerlies. The dominant storm track will be across the Aleutians and north into the Bering Sea. The 12Z ECMWF/CMC showed relatively good consensus through the first half of the forecast period, with a surface low crossing western mainland Alaska Sat night/Sun, and precipitation spreading across portions of the Interior. Farther east, another relatively weak wave of low pressure should move along a lingering frontal boundary in the Gulf of Alaska Sun night-Mon, bringing a round of precip to the Panhandle/Southeast Alaska. After that - the storm track shifts west, with most guidance showing a relatively deep low pressure system crossing the western Aleutians/Bering Sea Mon night-Wed (potentially a couple waves of low pressure, although the finer scale details remain difficult to resolve given the time range). This system is forecast to be relatively deep (likely below 980 hPa), resulting in the potential for strong/high winds across portions of the Aleutians Mon-Tue. Strong warm advection ahead of this system should spread additional precipitation across the Aleutians/Alaska Peninsula and into portions of western mainland Alaska. Models show yet another similar low pressure system approaching the western Aleutians by late next Wed/early Thu. Model differences on track/timing were a bit higher both of these systems, so gradually increasing emphasis on ECENS/GEFS ensemble means by that time helped smooth out some of these differences toward a consensus solution. Given these considerations, a blend of the 12Z ECMWF/CMC was used initially on day 4 (Sun), with a gradual trend toward heavier weighting of ensemble means each consecutive day, and a majority ensemble means after day 6 (Tue). Additionally, with the building upper-level ridge, temperatures are forecast to warm to near or above average across much of the state - the North Slope being the significant exception where colder conditions should linger at least through early next week before perhaps some moderation by midweek. Ryan 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 the Alaska Panhandle and mainland Alaska, Sat, Feb 8. - Heavy precipitation across portions of the Alaska Panhandle and mainland Alaska, Sun, Feb 9. - High winds across portions of mainland Alaska and the Aleutians, Sat-Mon, Feb 8-10. 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