Area Forecast Discussion
Issued by NWS Anchorage, AK
Issued by NWS Anchorage, AK
884 FXAK68 PAFC 060033 AFDAFC Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 333 PM AKST Wed Feb 5 2025 .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3)... Discussion: A weak shortwave trough will continue to work its way around the eastern periphery of the upper ridge, and across the Copper Basin, this afternoon and evening. The system will allow a slight reinforcement of colder air to filter in on the backside of the system allowing temperatures across the upper Susitna Valley and Copper Basin to see lows drop back down to zero to ten below by Thursday morning as cloud cover mostly clears overnight. The wave did little but dampen the ridge amplitude slightly, and the upper ridge will quickly build back over the the Gulf and much of mainland Alaska by this weekend. This will allow for continued dry weather for Southcentral with periods of low stratus or fog for some of the interior valleys and areas along the Cook Inlet that typically like to fog in with a strong low-level inversion set-up. With surface low out in the Gulf quickly dropping southwards tonight, gusty winds in Whittier/Passage Canal and Seward/Resurrection Bay will decrease as gradient slackens. The gradient looks to linger a bit longer along the northern Gulf coast keeping winds gusty for the Copper River Delta and Valdez areas. -PP && .SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS (Days 1 through 3: Today through Saturday)... The large ridge of high pressure that has persisted all week continues to persist in the southwest mainland. As a result of the stable air mass, chances for fog remain in The Kuskokwim Delta and especially Bristol Bay. Once again, the fog becomes sporadic in the daytime hours as solar heating increases in magnitude each day due to higher solar angles. The fog usually builds back in during the nighttime hours and will continue to do so for the next couple of days, particularly in Bristol Bay. Moisture is flowing around the ridge and some of it is making into the Bethel region, especially closer to the coast. Temperatures in this region are around freezing, but temperatures aloft are expected to remain cold enough to prevent freezing rain from becoming an issue. Precipitation that falls will likely be in the form of a rain/snow mix. By Thursday afternoon, the ridge will expand northwards, markedly decreasing chances for precipitation in this region, though lingering showers could be possible through Friday. The eastern Aleutians`, Alaska Peninsulas`, and Pribilofs` weather are currently influenced by the giant ridge that is in place, bringing drier, warmer weather with some fog as well. On the other hand, the western Aleutians from Shemya to Adak are currently experiencing rainfall and higher wind speeds as a north Pacific low rises from the south. As this low rises, it will start attacking the ridge, slowly pushing it eastward. Heavier precipitation and gale force winds will impact the Adak region by Thursday afternoon. By Friday, a second low center will swing around the first one, pushing the ridge even further and breaking its hold on the eastern Aleutians and Alaska Peninsula as more shortwaves follow from behind. Gale force winds and heavy precipitation will impact the Fox Islands, Pribilof Islands and the Cold Bay region by Friday afternoon. By Saturday, the ridge will be in full retreat eastward, allowing frontal systems to impact the southwest mainland. Wind speeds will increase along the coast, including the Kuskokwim coastline, where coastal flooding could occur by Sunday as multiple frontal waves impact the area over the weekend and beyond, keeping wind speeds elevated. Warm air will stream into the southwest mainland, increasing temperatures over the weekend. However, temperatures aloft will rise above freezing first as the surface flow remains offshore, while winds aloft become onshore. This could give the Bristol Bay region around Dillingham a chance of a snow/freezing rain mix by Saturday afternoon before winds shift more southerly on the surface and warm the area above freezing. -JAR && .LONG TERM FORECAST (Days 4 through 7: Sunday Through Wednesday)... On the Alaska Weather map, a broad upper level low over the Bering continues to weaken with several shortwaves troughs rotating through the pattern. A low center over the Western Aleutians slowly retreats towards Kamchatka through midweek. The active weather events have been slowly spreading Eastward through the forecast period. An broad upper level ridge remains over Mainland Alaska, slowly weakening as the shortwaves transit across the Northern edges. A deterministic GFS/ECMWF and Canadian blend supports the larger scale elements into the new week, with the most uncertainty associated with the smaller details moving through the flow. Forecast models change over to an ensemble blend to carry the features through Wednesday. The forecast period opens with the first of a series of lows and fronts These systems will bring widespread snow over most of the Northern Bering changing to locally moderate rain and gusty winds across the Eastern Aleutians, Alaska Peninsula, Kodiak Island and into Bristol Bay and Southwest Alaska Sunday. A well developed low and front moving into the Western Aleutians Sunday spreads a repeated round of locally heavy rain and gusty winds across the Aleutians and Bering through Wednesday. An opening period of gale force winds are expected over the Western Aleutians diminishing Monday. A third low and front repeats the process across the Western Aleutians and Bering for Wednesday. Mainland Alaska`s relatively quieter weather continues through midweek. -KZ && .AVIATION... PANC...Light winds will persist. Periods of fog and low stratus will likely develop again overnight and then slowly dissipate late morning to early afternoon Thursday. && $$