Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 743 PM EDT Mon Apr 14 2025 Valid 12Z Fri 18 Apr 2025 - 12Z Tue 22 Apr 2025 ...General Overview... The strong storm system that is expected to affect the Gulf region Thursday is forecast to weaken going into Friday with some lingering showers and wind, and steadily waning in intensity. Scattered rain and snow showers continue across the mainland through Saturday with the upper level trough in place. The next organized storm system develops over the central/western Aleutians over the weekend and will likely track in the general direction of the southeast Bering come Monday morning, bringing more rain/mountain snow and gusty winds. Ahead of this storm will likely be a building ridge axis from the Gulf to the Interior, which may break down by Tuesday depending on what the Bering Sea low pressure system does. ...Guidance/Predictability Assessment... The 12Z model guidance suite, along with the 18Z GFS, are in good synoptic scale agreement across the Alaska domain to close out the work week. The GFS depicts a trailing shortwave across the northern Gulf on Saturday after the earlier system weakens that is not favored by the model consensus, but remains in good agreement elsewhere. Looking ahead to Sunday and beyond, more meaningful differences begin emerging over the Bering and Aleutians, with the CMC slower and more amplified with the next storm system crossing south of the Aleutians, and the GFS becoming more progressive. There is better agreement on the upper level ridging building back in across the mainland. By the end of the forecast period Tuesday, high model spread exists across the North Pacific, with the 18Z GFS a very strong outlier with a storm system south of the central Aleutians, and does not have much GEFS ensemble support. The WPC forecast transitioned to about 60% ensemble means by Tuesday. ...Weather/Hazards Highlights... Moderate to locally heavy rain across the southeastern Alaska coast and snow in the St. Elias Mountains should be tapering off going into Friday with the storm system over the Gulf weakening. Gales are still possible over the open waters of the Gulf with mainly westerly flow. Scattered to numerous showers and mountain snow showers are expected across the central and southern portions of the Interior and Brooks Range for Friday and into Saturday, mainly during the afternoon and early evening hours when instability is greatest. Attention then turns to the Aleutians storm by Sunday with southerly flow advecting moisture towards the terrain of the Alaska Peninsula, and eventually Kodiak Island and the Kenai Peninsula by early next week. This does not appear to meet hazardous level criteria for now, but this will continue to be monitored in the days ahead. Temperatures are expected to be near to above average across central and western portions of the state, and below average across the northeastern mainland where the Arctic high will have more of an influence on the weather. 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