Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 748 PM EDT Thu Apr 14 2022 Valid 12Z Mon Apr 18 2022 - 12Z Fri Apr 22 2022 ...Deep cyclone transitioning from western Pacific Typhoon Malakas likely to affect the Aleutians early next week... ...Overview... Expect the primary focus of significant systems during next week to be near the Aleutians and over the northeastern Pacific. Deep low pressure originally associated with Typhoon Malakas should track over and then southeastward from the Aleutians early next week, bringing strong winds/enhanced precipitation and maritime threats. Another potentially strong system could track near the Aleutians later in the week but with lower confidence in the details at this time. Meanwhile an area of mean low pressure will likely exist south of the Panhandle for most of the period, with an initial system ultimately being replaced by a somewhat weakened form of the leading Aleutians storm. The combination of these features may bring some moisture northward into the Panhandle. Farther north, an upper ridge centered near the northern coast of the mainland should weaken somewhat but lingering ridging could persist into late week, while lower heights with troughing/one or more weak upper lows may prevail near the southern coast. ...Guidance/Predictability Assessment... There is reasonable large scale agreement for the overall Aleutians and northeastern Pacific pattern but there are meaningful differences for some details. Some timing spread develops for the first Aleutians storm associated with Typhoon Malakas by Tuesday, with the 12Z GFS a bit on the faster side and 12Z CMC becoming slowest. An intermediate solution looks reasonable and provides good continuity. There are greater differences for the next system that may affect the Aleutians later in the week, including details of evolution as well as timing. Overall the latest GEFS/CMC/ECMWF ensemble means support a slower system than forecast by the GFS. The 00Z and 12Z ECMWF runs differ in the specifics while an average of their runs fits well with the means. Thus after midweek the forecast blend excludes the GFS and emphasizes the past two ECMWF runs and 12Z GEFS/00Z ECMWF means. The new 12Z ECMWF mean supports this approach. The 18Z GFS has slowed a little while becoming somewhat of a deep extreme. Within the general area of low pressure south of the Panhandle, predictability for specifics appears to be on the moderate to low side given the small scale of initial low pressure and then eventually some dependence on timing of the second Aleutians system. A blend approach reflecting upstream preferences should provide a reasonable starting point for the time being. Guidance has displayed various ideas for specifics of upper flow over the mainland after the initial ridge centered near the northern coast weakens. These include energy drifting up from the south as the ridge retreats, some eventual influence from cyclonic flow to the northeast, or persistence of ridging to some degree. The favored blend leans a little more to the latter and the new 12Z ECMWF mean has trended more to the persistence scenario as well. ...Weather/Hazard Highlights... The extratropical reflection of Typhoon Malakas tracking near the Aleutians around Monday will produce a broad area of strong winds/maritime threats and precipitation from the Bering Sea through the North Pacific early next week. Another strong storm may track near the Aleutians by Thursday-Friday with associated enhanced winds and precipitation. This system could extend its influence at least as far east as the Alaska Peninsula. Relative to the first system, there is greater uncertainty with details of the late week system so continue to monitor latest forecasts for updated information. After Monday a couple surface systems to the south of the Panhandle may push moisture far enough north to bring precipitation to portions of the region. Confidence is fairly low for exact amounts/coverage but most activity should be on the lighter side. Much of the mainland should be fairly dry with at most very light/scattered precipitation. In general expect above normal temperatures over most of the northwestern half of the mainland and below normal readings over the southeastern half of the mainland and the Panhandle. Some areas may see slightly warmer anomalies for morning lows relative to daytime highs. Rausch Hazards: - Heavy precipitation across portions of the Aleutians, Mon, Apr 18. - High winds across portions of the Aleutians, Mon, Apr 18. 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