Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 507 PM EST Thu Jan 13 2022 Valid 12Z Mon Jan 17 2022 - 12Z Fri Jan 21 2022 ...Overall weather pattern... The beginning of the forecast period on Monday is expected to be rather uneventful across most of Alaska with high pressure governing the overall weather pattern. By mid-week, a low pressure system is likely to develop over the Gulf and then affect the southern mainland coast and the southeast Panhandle. Farther west, a large low pressure gyre just south of the central Aleutians, with multiple shortwaves pivoting around it, will tend to keep conditions rather unsettled across the Aleutians for most of next week ...Guidance/Uncertainty Assessment... The 12Z model guidance suite has a decent overall depiction of the synoptic scale pattern across the Alaska domain for the beginning of next week, with the most apparent differences with shortwave energy pivoting around the eastern periphery of the large scale north Pacific low. Recent runs of the GFS have trended a bit eastward with the low entering the Gulf by midweek, whereas the ECMWF has indicated a bit more run-to-run variability and the CMC is a weaker solution. By the end of next week, the GFS and its ensemble mean are closest to the central Aleutians with the big north Pacific low, and the CMC farthest south with the ECMWF/ECENS offering more of an intermediate solution. The greatest amount of ensemble spread appears across the Arctic region with timing and magnitude of smaller scale shortwave perturbations. The WPC fronts/pressures forecast is primarily based on a GFS/ECMWF/some CMC blend through midweek, and then about half of the ensemble means whilst still keeping some of the aforementioned deterministic guidance through Thursday and Friday. ...Weather/Hazard Highlights... Temperatures are generally expected to be below average north of the Brooks Range and also near the Seward Peninsula and adjacent areas of western Alaska, with some -40s for lows possible by late in the week. Much of the Interior and southern mainland should be near to above average for most of the week. In terms of precipitation, an axis of moderate to heavy mountain snow and coastal rain is likely for the southeast Panhandle region by late Wednesday as the Gulf low approaches. Multiple rounds of precipitation and gusty winds can be expected for most of the Aleutian chain with persistent low pressure nearly anchored in place over the north Pacific. Most of the Mainland should remain dry with perhaps a few isolated snow showers. Hamrick 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