Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 702 PM EST Thu Jan 11 2024 Valid 12Z Tue Jan 16 2024 - 12Z Sat Jan 20 2024 ...Stormy conditions for southwestern Alaska... ...Overview... Strong winds across the North Slope initially will reduce speeds near the start of the extended period as the upper low tracks west and ridging builds over the Interior and Aleutians. The upper ridge will likely break down early next week, with increased precipitation chances along the southern coast into Southeast Alaska, and potentially into portions of the Interior as well. ...Guidance Evaluation/Preferences... The non-GFS guidance overall have a decent grasp on the pattern change that will transpire during the extended period. As the week progresses, the ridging will shift more so over the western/central Mainland and the Aleutians will troughing setups over the East and Southeast. The GFS (GEFS mean) was not utilized for this cycle since it was mostly out of phase with the other global model and want to bring a very storm atmospheric river event into the Panhandle while other solutions do not. However it was within the vicinity of the low/trough that the CMC and ECWMF had in the Gulf at the very end of the extended period. Overall the CMC, ECWMF and the EC ensemble mean is fairly clustered with the ridging spreading west over the Aleutians while and inverted trough shifts north/east across the North Pacific/Gulf of Alaska. Upstream over the Bering Sea, there is general agreement in bringing the upper-level trough over the Bering Sea eastward along the southern coast and over the Gulf of Alaska, helping to break down the interior Mainland ridge from the west. The latest WPC forecast had an initial starting point of the ECWMF/UKMET/CMC/EC ensemble mean through Day 5 and beyond it was primarily CMC/ECWMF/EC ensemble mean. ...Weather/Hazards Highlights... The amplified pattern will keep winds rather gusty with a tight surface pressure gradient focused along western portions of the Mainland, as well along the North Slope. The strongest gusts are expected for eastern portions of the North Slope Saturday into Sunday as the northern portion of the interior ridge breaks down. The combination of snow, particularly away from the coast and into higher elevations, as well as the gusty winds could lead to some blizzard conditions. Despite some disagreement with respect to timing in the guidance, the upper trough/surface low are expected to continue eastward along the southern coast of Southcentral Saturday and eventually towards Southeast by Sunday, with some areas of heavy precipitation possible, but not particularly anomalous for this time of year. The approach of the upper trough/low pressure system over the Alaska Peninsula/southwest and along the southern coast may allow for at least some moisture/precipitation to spread inland into western and central portions of the Interior. Another system upstream over the Bering Sea will also potentially bring an additional round of precipitation to the western coast and Interior early next week. The western two-thirds of the Mainland will see milder than average temperatures, with the highest anomalies across northern and western portions of the Mainland. The Southeast will begin with below/well-below temperatures and are expected to moderate by mid/late week. With the pattern change into early next week, temperatures across the Mainland are likely to cool closer to normal as well. Campbell 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