Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 655 PM EST Mon Mar 07 2022 Valid 12Z Fri Mar 11 2022 - 12Z Tue Mar 15 2022 ...Overview... A Siberia upper ridge and its surrounding flow will dominate the pattern at higher latitudes, with progressive flow across the mid-latitude Pacific and varying forms of elongated mean troughing between the two. From late this week into the weekend expect the upper ridge to extend far enough into the mainland to keep a modest weakness over far southern/eastern areas. Then consensus shows a strong shortwave rounding the ridge during the weekend and dropping into the mainland early next week--ultimately leading to a northeast-southwest trough by next Tuesday. This feature may contain an upper low for at least a part of the period. Meanwhile low pressure near the Aleutians/Alaska Peninsula late this week should weaken thereafter, followed by a mid-latitude storm that may track close to the Panhandle by next Tuesday and an upstream system that tracks a little south of the Aleutians. ...Guidance/Predictability Assessment... Latest models and means provide reasonable similarity for the large scale pattern evolution but with some typical uncertainties for the details. Comparisons supported starting the forecast with a 12Z operational model blend (somewhat more ECMWF and GFS relative to the UKMET and CMC, all in order from most to least weight) which eventually transitioned to half models/half means by next Tuesday. During the latter half of the period the ECMWF component consisted of both 12Z and prior 00Z runs. Guidance generally shows at least a couple areas of low pressure over the Aleutians/southern Bering Sea into the Alaska Peninsula early in the period, including a front that extends into the Gulf of Alaska as of early Friday. These lows should weaken with time. There is also a hint of weak waviness that could reach the northeastern Pacific, but most likely missing the Panhandle either by dissipating or tracking to the south. The favored model blend in this time frame reflected the most common elements of the forecast while downplaying features with the least confidence. For the pattern over the mainland and vicinity during the first part of next week, the best consensus shows a strong shortwave (with possible embedded upper low) dropping into the area from the north to yield a northeast-southwest trough by next Tuesday. Recent ensemble means have depicted such a trough but in modest fashion. Operational model runs have varied more significantly, though latest solutions offer a deeper trough than the means and still the potential for an upper low. Prior variability made the model/mean approach a reasonable starting point, trending deeper than continuity for the trough but not to the degree of the operational runs yet. The new 12Z ECMWF mean came in noticeably deeper than past runs. Finally, there is a general clustering of models/ensembles for a potentially strong mid-latitude Pacific storm that should weaken somewhat by the time it approaches the Panhandle next Tuesday while another system likely tracks just south of the Aleutians. Details of mainland troughing may begin to have some influence on this latter system by next Tuesday. ...Weather/Hazard Highlights... The southern coast and Panhandle may see some light to moderate precipitation late this week with a frontal system but expect this activity to trend lighter during the weekend. Lighter and more scattered precipitation may extend a little farther north into southern parts of the mainland. Portions of the Panhandle may see another episode of precipitation early next week with the mid-latitude Pacific system that eventually tracks toward the region. The Aleutians may see a period of increased precipitation/winds around late weekend and early next week with a system passing by to the south. Precise effects on the Aleutians will be very sensitive to storm track, and typical guidance error 6-7 days out in time keeps confidence low in defining specifics at this time. Expect above to well above normal temperatures over a majority of the mainland from late this week into the weekend, with the primary exception being some moderately below normal readings in eastern and central interior areas. Upper troughing forecast to settle over the mainland next week should promote a cooling trend, with increasing coverage of below normal temperatures and especially for daytime highs. The Panhandle will likely see below normal highs for most of the period and a mix of above/below normal lows. Rausch No significant hazards are expected over Alaska during this forecast period. 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