Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 646 PM EDT Mon Mar 31 2025 Valid 12Z Fri 04 Apr 2025 - 12Z Tue 08 Apr 2025 ***Heavy coastal rain and heavy mountain snow makes a return to southern Alaska for Friday into the weekend*** ...General Overview... A generally mild pattern is expected to be in place across most of the Alaska domain for the end of the week into the weekend, with an upper level ridge axis building northwest into the central and eastern mainland from western Canada. Meanwhile, a large low pressure system organizes over the Gulf and slowly moves towards the Alaska Peninsula, and brings a return to heavy coastal rain and mountain snow to southern Alaska late Friday and into the weekend. Lighter valley rain and mountain snow is expected across portions of the Interior as the moisture advects inland. ...Guidance/Predictability Assessment... The 12Z model guidance suite features good overall agreement across the Alaska domain for the end of the week with some mesoscale differences noted across the Arctic and the North Pacific, so a CMC/ECMWF/GFS model blend suffices as a starting point in the forecast process. The UKMET is faster and to the north of the model consensus with the Gulf low. The CMC diverges from the ECMWF/GFS/ensemble means consensus by Day 6 across the Arctic, so it was reduced by Day 6 and beyond. By next Tuesday, a broad trough axis tries to become established over the state as the Arctic trough amplifies more and the weakening low from the Gulf lifts northward, although the guidance differs on specifics. The ensemble means were gradually increased to about half by early next week, with equal weighting of the ECMWF/GFS/ECENS/GEFS. ...Weather/Hazards Highlights... Heavy precipitation becomes increasingly likely for the southern coastal areas from the Alaska Peninsula to the Prince William Sound, and then western portions of the southeast panhandle going into Friday and the weekend. An expansive area of low pressure develops over the central/southern Gulf and slowly lifts north, bringing a return to moist and strong onshore flow with coastal rain and mountain snow, which will likely be heavy at times and potentially anomalous by April standards. This surface low has trended steady compared to yesterday's model runs. Gale force winds are likely over the open waters of the Gulf, and storm force gap winds are possible for the eastern Aleutians and portions of the Alaska Peninsula on Friday and early Saturday. Temperatures are generally expected to be above average across the majority of the state for most of the forecast period, with readings closer to early April averages across far western portions of the mainland. It appears the greatest anomalies will likely be over southeastern portions of the mainland, where afternoon highs could reach near or just over 50 degrees for some of the valley locations. A cooling trend likely commences for early next week as the Arctic trough tries to build back in. 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