Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 644 PM EDT Sun Apr 27 2025 Valid 12Z Thu 01 May 2025 - 12Z Mon 05 May 2025 ...General Overview... The first days of May are expected to be rather unsettled in terms of expected weather conditions from the Alaska Peninsula to the southeast Panhandle, courtesy of multiple low pressure systems and moist onshore flow from the Gulf. Aloft, a broad upper low is expected to be in place across the Bering for the middle to end of the week, and then pivoting to the Gulf by next weekend and next Monday. Meanwhile, the Arctic surface high will continue to be strong and result in sustained polar easterlies north of the Brooks Range, and continued below average temperatures in many cases. ...Guidance/Predictability Assessment... The 12Z model guidance suite features good overall model agreement for the middle to end of the week, and therefore a deterministic model blend suffices as a good starting point in the forecast process. Looking ahead to next weekend, timing differences become more apparent across the North Pacific, especially with the second system approaching the Gulf region. There has been a northward trend in the guidance with that low compared to yesterday by roughly 100 miles or so. Similar to yesterday, the CMC remains slower than the model consensus with the arrival of that weekend system, and therefore more weighting was applied to the ECMWF/GFS and their ensemble means for Sunday into Monday. ...Weather/Hazards Highlights... Late season heavy rainfall is still expected from eastern portions of the Alaska Peninsula to the Prince William Sound region for the middle of the week. An atmospheric river is likely east of a northern Gulf low Wednesday into Thursday morning, with 2-4 inches of liquid equivalent for the south facing terrain. Although there should be some abatement in precipitation intensity going into the end of the week, it will unfortunately remain unsettled for the southern coastal areas with damp onshore flow continuing and periods of rain and mountain snow. Depending on what the next system does next weekend, there will likely be a return of additional rainfall for the southern coastal areas and extending to the southeast Panhandle. A quasi-stationary frontal boundary draped across the Interior for most of the forecast period will separate a mild and spring-like airmass across south-central Alaska, from a much colder and polar-like airmass from the Brooks Range northward. Temperatures are generally expected to be below average with the Arctic surface high continuing to govern the overall weather pattern. 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