Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 648 PM EST Wed Jan 08 2025 Valid 12Z Sun Jan 12 2025 - 12Z Thu Jan 16 2025 ...Active pattern culminates with a deep cyclone impacting mainland Alaska with high winds and heavy precipitation especially across the southern mainland later this weekend... ...General Overview and Model Guidance Assessment... Multiple energetic disturbances rotating around an large upper-level gyre centered near the northern portion of the Bering Sea will culminate with a deep cyclone forecast to traverse the entire mainland Alaska from south to north later this weekend into early next week. Despite the rapid successions of these disturbances, model guidance today shows surprisingly good agreement in predicting their timings and depths, even out to Day 8. The 06Z GFS appears much too fast with the next smaller-scale cyclone to rapidly head northeast toward the Alaska Panhandle early next week. Otherwise, a general model compromise appears to suffice in providing a good starting point for today's edition of the medium-range forecast package for the Alaskan domain. The model blend consists of 40% from the 12Z GFS/GEFS, 40% from the 12Z ECMWF/00Z EC mean, and 20% from the 12Z CMC/CMC mean. It was noted that this blend yielded a faster motion of the smaller-scale Pacific cyclone to head toward the northern Panhandle next Tuesday compared with yesterday's WPC prognostic chart. Meanwhile, models show very good agreement to bring the center of the deep cyclone to the northeast of Alaska at a weakened state by next Tuesday. Models also indicate good signal for another weaker cyclone to track across the Aleutians into next Wednesday. A deeper cyclone will then appear to track eastward to the south of the Aleutians heading into Thursday. ...Weather/Hazards Highlights... The active synoptic pattern that continues to bring back-to-back fast-moving and energetic disturbances toward the southern coastline of Alaska will likely culminate with a deep cyclone to traverse the entire state by this weekend into early next week. The eastern Alaska Peninsula/Kodiak Island will likely see the heaviest precipitation with the higher elevations likely receiving snow to be measured in feet. Widespread high winds can be expected to overspread all of southern Alaska on Sunday together with the heavy coastal rain and mountain snow. Flooding could very well become a problem in some of the lower elevations where enhanced run-off expected. Given central pressures possibly falling below 960 mb with the incoming deep cyclone on Sunday, winds strengthening to storm-force can be expected for the coastal waters along with hurricane-force wind gusts. As the center of the cyclone tracks northward up the west coast of mainland Alaska early on Monday, southerly flow ahead of the system could surge temperatures to record levels, with highs possibly reaching 40 degrees for portions of the interior sections. The anomalously warm conditions will likely prevail across the rest of the Alaskan domain with readings possibly returning closer to normal by the latter portion of next week. Meanwhile, other locations in western Alaska will likely see moderate to possibly heavy snow at some locations from later on Sunday through Monday and possibly into early Tuesday as the cyclone center passes in the close distance, followed by the arrival of colder air from the back side of the cyclone. A blustery northeasterly flow from the Arctic Ocean will prevail from the North Slope to the Arctic Coast with the approach of the deep cyclone this weekend along with areas of snow. As the cyclone gradually weakens early next week and relocates to the north of Alaska, winds will shift to the southwesterly direction for much of mainland Alaska. Meanwhile, heavy mountain snow and coastal rain ahead of a potent front trailing southeast from the deep cyclone will likely impact the Alaska Panhandle Sunday night into early Monday before the precipitation gradually tapers off. A weaker cyclone will bring the next round of precipitation through the Aleutians early next week, possibly reaching the Peninsula by midweek, as the next deeper cyclone comes into the picture to south of the Aleutians. Kong 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