Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 657 PM EST Sun Jan 26 2025 Valid 12Z Thu Jan 30 2025 - 12Z Mon Feb 03 2025 ...Much colder temperatures likely into late week... ...Overview... An amplified and initially progressive pattern is likely for Alaska through the extended period. An upper trough axis will be atop the eastern Mainland to the Gulf midweek, with precipitation lingering for Southeast Alaska on the eastern side of the trough while northwesterly gap winds may linger into Thursday for parts of the Alaska Peninsula/Kodiak Island and surrounding waters. Much colder temperatures compared to the near term/short range are expected under the trough, but an upper ridge moving into western Alaska late week and central Alaska next weekend should lead to warming temperatures once again. Moist inflow east of Bering Sea troughing just behind this ridge will increase precipitation chances across the Aleutians, Alaska Peninsula, and western Mainland late week into next weekend. ...Guidance Evaluation and Preferences... Model guidance shows reasonably good agreement with the pattern described above. After some model runs (mostly CMC) that lingered the first upper trough farther west across the Mainland into late week, the 12Z guidance came in more agreeable with what had been the predominant model solution all along--the trough moving more progressively eastward. Just upstream, models show an upper ridge building as it shifts slowly from the eastern Bering Sea late week into the Mainland over the weekend. There are some minor timing differences into early next week and some possibility for shortwaves along its periphery that are naturally more uncertain. At the surface, an Arctic high is forecast for late week in the northern half of Alaska, strengthening as it drifts into northwestern Canada over the weekend and early next week. The more uncertain part of the forecast is with a mean trough axis setting up over the Bering Sea to Aleutians to northern Pacific. Shortwaves within the trough and surface lows show more spread without much clear clustering in a solution. At least the broad pattern of troughing in the region is shown by models and ensemble means. The WPC forecast used a blend of 12Z deterministic model guidance early in the period, namely the ECMWF, GFS, CMC, and UKMET from highest to lowest percentage of the blend. Included the GEFS and EC ensemble means in the blend and increased their proportion to half by Day 8 amid increasing uncertainty. ...Weather/Hazards Highlights... Modest precipitation is forecast to decrease Thursday-Friday across Southeast Alaska, drying out completely by the weekend. A strong Arctic high in northwestern Canada and relative low pressure offshore may channel winds in favored areas of Southeast by the weekend, depending on the orientation of the pressure gradient. Moderate to high winds may also be a concern into early Thursday as northwesterly flow forms gap winds that funnel in typical areas like on either side of Kodiak Island. Then frontal systems and lows will be tracking across the northern Pacific/Aleutians/Bering Sea, leading to precipitation spreading across the Aleutians and Alaska Peninsula late week. Southerly gusty winds are possible in those areas as well. Some precipitation is forecast to spread into the western Mainland next weekend and early next week, but it is uncertain how far east precipitation will reach into the central part of the state. Temperatures will be much colder, and much below average for the Mainland aside from the North Slope, as the period begins Thursday. Lows will be in the -30s and even -40s in the Brooks Range and parts of the Interior, with cold highs staying in the -20s (-30s in Fort Yukon). Coldest anomalies should nudge eastward Friday into the weekend, as western areas start to moderate to above normal under the upper ridge. By Sunday-Monday the North Slope and at least the western half of the state can expect above average temperatures. Tate Additional 3-7 Day Hazard Information can be found on the WPC medium range hazards outlook 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