Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 614 PM EST Mon Jan 27 2025 Valid 12Z Fri Jan 31 2025 - 12Z Tue Feb 04 2025 ...Much colder than normal temperatures lingering into Friday... ...Overview... An amplified and initially progressive pattern is likely for Alaska through the extended period. An upper trough axis initially over the eastern Gulf/Panhandle region will keep precipitation in the forecast into about Friday. On the west side of the trough, northwesterly gusty gap winds may be a concern for parts of the eastern Peninsula and Kodiak Island through Thursday. Much colder than normal temperatures will linger through Friday for the central and eastern Mainland under the trough, but an upper ridge moving into western Alaska late week and central Alaska next weekend should lead to warming temperatures. Moist inflow east of Bering Sea troughing just behind this ridge will increase precipitation chances across the Aleutians, Alaska Peninsula, and western Mainland into next weekend and early next week. ...Guidance Evaluation and Preferences... Latest model guidance for today shows fairly good agreement on the overall large scale pattern described above, but plenty of uncertainty in the details. The greatest area of uncertainty lies with individual shortwaves and surface lows rounding the base of the mean troughing over the Bering Sea, through these should not have any impact on the mainland. One surface low looks to cross the western Aleutians this weekend, as another one approaches early next week. Downstream, there is disagreement in how strong ridging is over the Mainland and whether smaller scale shortwaves try to erode the northern part of the ridge across western Alaska. The consensus of guidance says this is likely, but the 12z CMC continued to show a strong upper high over the state. This was an outlier solution and not preferred. The WPC forecast for today used a blend of the 12z deterministic guidance early in the period, with slightly more weighting towards the GFS and ECMWF. By Day 6 and beyond, gradually increased the ensemble means to 60 percent of the blend by Day 8, along with 40 percent of the GFS and ECMWF. ...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 gap areas of the Southeast by the weekend, depending on the orientation and strength of the pressure gradient. Moderate to high winds may also be a concern into Thursday as northwesterly flow funnels winds in typical gap 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 possibly into the Alaska Peninsula late week. Southerly gusty winds are possible in those areas as well near/along the associated cold fronts. Some precipitation is forecast to spread into the western Mainland next weekend and early next week, with some enhancement likely across the higher terrain of the Seward Peninsula and western Brooks Range. Some uncertainty on the exact amounts and how far eastward the precipitation shield will extend. Temperatures will be much below average for the central and eastern Mainland as the period begins Friday. These should quickly shift eastward into the weekend as upper ridging brings in warmer and average air. The greatest anomalies will be on the North Slope, where daytime highs could be 30+ degrees above normal. Santorelli 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