Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 543 PM EST Wed Jan 29 2025 Valid 12Z Sun Feb 02 2025 - 12Z Thu Feb 06 2025 ...Gusty gap winds possible across southeast Alaska this weekend... ...Overview... An initially amplified pattern is likely when the period begins Sunday with an upper low positioned over the northeast Pacific and an anomalously strong ridge building over the Mainland. This should promote a period of much warmer than average temperatures across much of the Mainland (with the exception of the Southeast). On the east side of the ridge, strong northerly gap winds continue to be a concern for parts of the Panhandle region this weekend. Meanwhile, mean troughing will prevail into at least early week across the Aleutians and western Bering, though with a lot of uncertainty on individual shortwaves/surface lows rounding the base of the trough. Moist inflow east of this trough will increase precipitation chances across the Aleutians, Alaska Peninsula, and western Mainland into next weekend and early next week with some gusty winds. The pattern looks to turn less amplified with some breakdown of the upper ridge expected by the middle of next week. ...Guidance Evaluation and Preferences... Latest model guidance for today shows fairly good agreement on the overall large scale pattern described above, especially the first half of the period, but plenty of uncertainty in the details. There continues to be a lot of uncertainty with individual shortwaves and surface lows rounding the base of the mean troughing over the western Bering Sea into early next week, through these for the most part should not have any impact on the mainland. There is a shortwave or two which may push into western Alaska, acting to help break down the ridge. A lot of run to run inconsistencies with this though, and the GFS is the strongest with such a shortwave into the Mainland. General agreement though for a less amplified pattern developing over the Alaska forecast domain and an eventual breakdown of the ridge. The evolution and details of this remains in question. The WPC forecast for today used a blend of the 12z deterministic guidance early in the period. By Day 6 and beyond, increased the ensemble means to 75 percent of the blend by Day 8, continuing to include a 25 percent combination of the GFS and ECMWF for a little extra system/pattern definition which becomes very washed out in the means (indicative of a lot of ensemble variability). ...Weather/Hazards Highlights... Northerly winds in between the upper ridge over the Mainland and the upper low over the northeast Pacific may channel winds in favored gap areas of the Southeast this weekend, depending on the orientation and strength of the pressure gradient. At the same time, frontal systems and lows will be tracking across the northern Pacific/Aleutians/Bering Sea through the weekend, leading to precipitation spreading across the Aleutians and possibly into the Alaska Peninsula. 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. Still some uncertainty on the exact amounts and potential impacts still. Above to well above average temperatures will shift from west to east this weekend across the mainland beneath a strong upper level ridge. The greatest anomalies will be on the North Slope and parts of far western Alaska where daytime highs could be 30+ degrees above normal Sunday-Tuesday. The exception to the warmth will be across Southeast Alaska where the upper low lingering just south of the Panhandle will keep temperatures below average into at least mid next week. 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