Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 756 PM EDT Fri Mar 17 2023 Valid 12Z Tue Mar 21 2023 - 12Z Sat Mar 25 2023 ...Overview/Guidance Evaluation/Predictability Assessment... A strong low pressure system approaching the Bering Straits will be the next weather feature to make headlines early next week. Even though the worst of the weather is currently expected to remain offshore over the Bering, strong southerly winds over 40 mph are possible for coastal portions of the southwestern mainland and the western Seward Peninsula, and may also result in elevated tides. By midweek, a new low pressure system is forecast to develop south of Kodiak Island and this should slowly drift east and then southeast across the Gulf, while high pressure continues to govern the overall weather pattern across the Interior. Another organized low pressure system may approach the Bering Sea region by next weekend, and a separate low could also get organized over the northern Gulf around this time as well. In terms of the model guidance, there was enough agreement among the GFS/ECMWF/UKMET to merit a blend of those models Wednesday night. The CMC is closer with the placement of the Bering Sea low to the model consensus compared to yesterday, but it remains to the east of the model consensus with the Gulf of Alaska low, so it was not favored for Wednesday and beyond. Towards the end of the week, recent GFS runs have trended weaker with the low south of the central Aleutians compared to yesterday, and it also shows a stronger surface high near the eastern Aleutians by Saturday compared to the other guidance. A gradual increase of the ensemble means was warranted for the second half of the forecast period owing to increasing mesoscale uncertainties. ...Weather/Hazard Highlights... The strong storm crossing the northern Bering is expected to produce widespread gusty winds for the western coastal areas, and gale to storm force winds across the open waters. Impactful winds and coastal flooding are likely to affect portions of the western mainland Alaska coast. In addition, there should be enough deep layer southerly flow ahead of this low to advect a warmer maritime air mass northward across much of the mainland and even across the Brooks Range and the North Slope. Widespread highs in the upper 20s to upper 30s are likely next week, and 10s north of the Brooks Range. A return to colder weather is likely by the end of the week across western Alaska as a colder air mass from Siberia moves into the region. Hamrick Hazards: - Heavy precipitation across portions of southern coastal Alaska, Tue-Wed, Mar 21-Mar 22. - High winds across western mainland Alaska and the Aleutians, Mon, Mar 20. 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