Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 538 PM EST Sat Feb 18 2023 Valid 12Z Wed Feb 22 2023 - 12Z Sun Feb 26 2023 ***Strong low pressure system to track across the Bering Strait midweek, bringing strong winds and periods of snow and coastal rain to western Alaska*** ...Model Guidance/Predictability Assessment... The 12Z model guidance initially has a good overall depiction on the large scale weather pattern through the middle of the week, with the normal level of mesoscale differences. There is excellent agreement on the building ridge axis from the Gulf to the eastern mainland through Friday, and then the ridge breaks down by the weekend. Going forward to next Saturday, the CMC differs significantly across the Aleutians and the southern Bering compared to the consensus. The fronts/pressures forecast was primarily derived from the GFS/ECMWF along with some CMC/UKMET for the first half of the forecast period, and then increasing the percentage of the ensemble means to about 50% by next weekend. ...Pattern Overview and Weather/Hazard Highlights... Upper level ridging and an accompanying surface high is forecast to be in place across much of mainland Alaska for the middle portion of next week, and then the ridge axis shifts to western Canada going into Friday and weakens as the broad trough from the Bering Sea moves northeastward. The main corridor for surface low tracks will tend to be favored over the western Aleutians to far eastern Siberia and the Bering Strait through the end of the week, and a northern Gulf low is expected to develop by late Friday into Saturday. An upper trough is also likely to develop over the Gulf by Saturday, and a new ridge axis tries to build northward over the southern Bering by next Sunday. The track of the surface lows across the western Bering is forecast to produce warm frontal snow across portions of western mainland Alaska for the middle to end of next week, and strong gusty southerly winds across western coastal areas of the state. There may even be some rain for portions of southwestern Alaska where highs manage to get into the mid-30s. More widespread light to moderate snow is becoming more likely across the Interior and the Brooks Range going into Thursday with increasing warm air advection. This will also lead to a surge of well above normal temperatures by late February standards, with highs potentially running 20-30 degrees above average across central and western portions of the mainland Wednesday through Saturday. This will equate to temperatures possibly getting above the freezing mark in some of these areas. It will initially be very cold north of the Brooks Range, but even here a strong warming trend is likely going into the end of the week. Colder weather is likely to make a return by the weekend as the cold front heralds an end to the unseasonably mild conditions. Hamrick 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