Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 635 PM EST Mon Jan 03 2022 Valid 12Z Fri Jan 07 2022 - 12Z Tue Jan 11 2022 ...Overview... As a persistent upper high over northeastern Russia finally reorients itself more west-east and retreats westward during the medium range period, this will lessen its influence on Alaska and allow for lower mid-upper heights to come into the state, with a busy storm track near the Aleutians and the northern Pacific/Gulf of Alaska. This will favor increasing moisture and brisk winds into southern parts of Alaska from the Aleutians late this week into Southcentral Alaska and the Panhandle by the weekend into early next week. ...Guidance Evaluation and Preferences... Model guidance particularly in terms of the ensemble means continues to show good consensus with the overall pattern, though with some typical model differences in the details. There is good predictability for the upper high over northeast Russia to shift west away from Alaska through the period. Meanwhile a strong shortwave is forecast to drop east of the high on Friday and round underneath the retreating ridge (also serving to push the high away) and retrograde westward across the mainland around Saturday. Additionally, a closed low moving eastward south of the Aleutians late week could interact/merge with that feature over the weekend/next Monday. This interaction potential remains somewhat uncertain, but guidance generally ends up showing a closed mid-upper low over or near the Aleutians by Monday-Tuesday. At the surface, the initial shortwave tracking south will likely result in a cold front pushing through eastern parts of Alaska late in the week, while possibly multiple surface lows spin in the northern Pacific/Gulf and bring precipitation chances to southern Alaska. Model guidance is incredibly variable with timing, strength, and placement of these surface lows, but at this point no clear outliers stand out. For the initial part of the medium range period, went with a deterministic model blend of the 12Z guidance somewhat favoring the ECMWF. Ended up with a 50% deterministic/50% ensemble mean blend by the end of the period after gradually increasing the components of the GEFS and EC ensemble means, which served to maintain some strength of features but blend out particular model variations. This provided good continuity from the previous forecast. ...Weather/Hazard Highlights... Precipitation during the latter part of the workweek will be generally limited to light to locally moderate rain/snow over the Aleutians to Kodiak Island, while much of the mainland should see dry conditions given periods of high pressure encroaching from the north. One exception over the mainland could be light snow showers for far northeastern Alaska as a weak surface cold front slips through northwest Canada on Friday. Then by next weekend, a warm front is currently forecast to push toward or into the Gulf stemming from low pressure over the northern Pacific, increasing moisture and potentially spreading rain/snow into Southcentral Alaska. The increase in moisture should also interact with the temperature gradient/stationary front along the Panhandle and bring possibly heavy precipitation there by the weekend into next Monday. Given the cold surface high pressure encroaching into Alaska, below normal temperatures remain forecast for the mainland especially south of the Brooks Range, gradually trending less extreme with time and may moderate to slightly above normal by early next week as the high retreats. After a chilly period during the short range for the Panhandle, potentially setting daily records for cold temperatures, below average temperatures should continue there through the end of the week with offshore flow, but also become closer to/above average as warmer/moist inflow comes in as next week begins. Meanwhile, the North Slope could see above normal temperatures Friday but then should cool to below normal. 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