Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 558 PM EST Sat Jan 21 2023 Valid 12Z Wed Jan 25 2023 - 12Z Sun Jan 29 2023 ...Threat of heavy precipitation along the southern coast to the Panhandle expected to last through around Thursday... ...The Aleutians toward the western mainland could see increasing chances of precipitation along with gusty winds late next week... ...Overview... With an overall trough-ridge pattern across Alaska Wednesday-Thursday, rounds of heavy precipitation remain a threat across southeastern coastal parts of the mainland as well as the Panhandle. Then ridging building in should lessen precipitation chances for the Panhandle and help create above normal temperatures for the bulk of the state. However, troughing and the influence of a large low pressure system over the Bering Sea is likely to create more active weather from the Aleutians into the Alaska Peninsula and western mainland by later next week. ...Model Guidance/Predictability Assessment... Model guidance has stayed reasonably well clustered for the overall pattern evolution but with typical differences in the details. Models have become more agreeable for a closed upper low to be located around/atop the Seward Peninsula for Wednesday-Thursday, which the ECMWF had been the first model to catch onto. Additionally, model consensus clusters well with a notable shortwave tracking across the Alaska Peninsula to Southcentral Alaska, and ridging building into the mainland after that. Meanwhile, a deep and large surface low pressure system looks to develop in the far western Bering Sea in and around the Kamchatka Peninsula. Models indicate central pressures in the 930-940mb range at times. While there are some variations with its track, model guidance still does not show this low tracking toward Alaska but show it weakening and passing farther west instead. But, shortwave energies and frontal boundaries with perhaps embedded surface lows associated with the large low have quite a bit of variety in terms of timing. More specifically, GFS runs seem to cluster best with the ensemble means with timing of a shortwave trough tracking into the state late week, while the 12Z ECMWF was significantly faster and the 12Z CMC significantly slower. The WPC forecast was based on a blend of the ECMWF/GFS/CMC/UKMET deterministic models early on, with incorporation and increase of the ensemble means by days 6-8 given the increasing uncertainty/detail differences. ...Sensible Weather and Potential Hazards... A trough pattern across the northwestern Alaska Mainland, as well as shortwaves and lows tracking across the Alaska Peninsula and Southcentral Alaska, will direct moisture into the Panhandle for additional rounds of heavy rainfall through around Thursday. Ridging set up there will cause temperatures to be milder than average for a precipitation type of predominantly rain for much of the Panhandle region. Temperatures are forecast to be 20-30F above normal south of the Alaska Range. Today's forecast update shows somewhat milder temperatures reaching northward across much of the mainland as well given the reorientation of the upper low farther west near the Seward Peninsula. But that upper trough/low will lead to an area of colder than average temperatures for the western mainland. Some residual moisture should make it into central parts of the mainland as well for some snow chances. By late next week, ridging becoming established into the mainland as well should help moderate temperatures to well above normal across the state with the exception of the near-normal Aleutians. Additionally, this should begin a drying trend across the Panhandle. Meanwhile, a large surface low pressure system is forecast over the western Bering Sea/Kamchatka Peninsula for the latter half of the week. While guidance continues to have this low weakening west of Alaska, it is becoming likely that its frontal boundaries will come across the Aleutians and toward the southwestern mainland/Alaska Peninsula around Thursday-Saturday, along with shortwave energy. Enhanced precipitation and perhaps some high winds are possible. Then some available moisture could lead to snow showers over much of the mainland through next weekend, but currently only light QPF is expected. 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