Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 653 PM EST Thu Feb 03 2022 Valid 12Z Mon Feb 07 2022 - 12Z Fri Feb 11 2022 ...Overview... The majority of guidance shows an upper-level evolution that appears to share some traits with an episode from a couple weeks ago, with elongated mainland trough energy pulling off an upper low that tracks into the Bering Sea while a building eastern Pacific ridge extends into northwestern North America. The flow between these features will carry two or maybe three systems, the first into the Gulf of Alaska and the latter one(s) likely somewhat farther west. These systems will bring periods of enhanced precipitation to the Panhandle and parts of the southern coast, and possibly farther north into the mainland depending on exact storm track. Heaviest precipitation should extend from the Kenai Peninsula into the Panhandle. ...Guidance/Predictability Assessment... As was the case in the previous episode involving this type of evolution, the operational ECMWF is the misfit relative to most other solutions by bringing its upper low farther east into/through the mainland by the latter half of the period--in contrast to the majority that keeps it farther west over the Bering Sea or at least begins to eject it on a farther northwest track. The 12Z ECMWF run adjusted somewhat westward of the prior 00Z run but still strays questionably far eastward by late next week. ECMWF means have been somewhat east of the GEFS/CMCens but are not nearly as extreme as the operational runs. Teleconnections relative to the strong core of positive height anomalies associated with the building East Pacific upper ridge also recommend leaning toward higher heights over the mainland than forecast by the ECMWF late in the week. Based on this large-scale consideration, the forecast started with an even blend of the 12Z GFS/ECMWF/CMC/UKMET for about the first half of the period and then eventually trended to slightly more total weight of the 12Z GEFS/CMCens and 00Z ECMWF mean relative to the GFS/CMC. This blend maintained fairly good continuity from yesterday's forecast in principle, with most changes involving greater strength/definition or modest adjustments in other details. There is good agreement that a leading storm should track into the Gulf of Alaska by early day 5 Tuesday. However the models are split over whether it will be the parent low from the previous day or development of a triple point wave while the original low stays back, either dissipating or somehow combining with the next system. Differences with the upper low farther north begin to have an influence on the track of this next surface low. ECMWF runs have been tracking it into the Gulf, the ECMWF mean a little west of the operational runs, and other solutions more into the Alaska Peninsula/Bristol Bay. Uncertainty increases further with the potential third system (around Friday) that could develop ahead of a larger-scale system to the south of the Aleutians. It is not reflected in the ensemble means but has been showing up in GFS runs and 12Z CMC. Plus the 12Z ECMWF has a slower version of it. The favored blend reflects this system, but in a conservative fashion while awaiting a more coherent signal from ensembles. Note that after the early part of the week there is still enough spread among non-ECMWF solutions for exactly how the Bering Sea trough/upper low will evolve to temper confidence in forecast details. ...Weather/Hazard Highlights... Southwesterly flow between the Bering Sea upper low/trough and the East Pacific/far western Canada ridge will support wet weather over southern Alaska during most of next week. Individual surface lows will periodically help to focus heavier episodes of rain in low/coastal areas and heavy snow in higher elevations. Highest totals are likely to be from the southeastern coast through the Panhandle while amounts over locations farther west will depend more on exact storm track. Each storm may also produce brisk to strong winds and rough seas between the Aleutians/Alaska Peninsula and the Panhandle. Some snow may extend farther north into the mainland mid-late week based on a most likely storm track into the southwestern mainland. The majority of the state should see below normal temperatures early next week, with Southcentral and the Panhandle tending to be the exception with above normal readings. The evolving upper pattern should promote a warmer trend by mid-late week, ultimately confining most of the below normal temperatures to the far western mainland. Rausch Hazards: - Heavy precipitation across the Alaska Panhandle into the southern coastal sections of Alaska, Sun-Thu, Feb 6-Feb 10. 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