Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 644 PM EST Sun Jan 02 2022 Valid 12Z Thu Jan 06 2022 - 12Z Mon Jan 10 2022 ...Overview... A blocky pattern will continue through much of the medium range period over the high latitudes as an upper high over northeastern Russia/Chukchi Sea meanders in place while reorienting itself before finally shifting west by early next week. This favors cold high pressure over most of the region south of the Brooks Range, while a storm track near the Aleutians and the southern part of the state leads to periods of generally light precipitation and brisk winds for the Aleutians late this week, before moisture is likely to increase for 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. The upper high centered over northeastern Russia and the Chukchi Sea should be reorienting itself more north-south by Friday and then becomes more west-east oriented by early next week as it shifts west, with reasonably good model agreement. A more active storm track will occur for southern Alaska due to a combination of energy tracking into the northern Pacific well south of the high as well as shortwave energy dropping initially southward to the east of the high around Friday and then retrograding across the southern half of the state, serving to push the high northwestward away from Alaska. At the surface, this likely will 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 and bring precipitation chances to southern Alaska. These features show more variability among guidance in timing, strength, and position, but at this point no clear outliers stand out. Most recent (12Z) guidance keeps surface lows south of the Aleutians and out of the Bering Sea, unlike some GFS guidance from the last couple of days. 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 60% deterministic/40% 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 half of next week 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 Thursday-Friday. Then by next weekend, a warm front is currently forecast to push toward or into the Gulf stemming from a low 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 south of the Brooks Range, gradually trending less extreme with time and moderating 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 with offshore flow until early next week. Meanwhile, North Slope will see well above average temperatures on Thursday before moderating closer to normal by the weekend. 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