Area Forecast Discussion
Issued by NWS Anchorage, AK
Issued by NWS Anchorage, AK
653 FXAK68 PAFC 040409 AFDAFC Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 809 PM AKDT Fri May 3 2024 .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3)... Southeasterly flow and weak upsloping continues areas of light precipitation mainly across Kodiak Island up through the eastern Kenai Peninsula, with some light drizzle expected to occasionally spill over the mountains into the western Kenai and Anchorage Bowl through early tonight. A front associated with a large mature low over the Bering will then push into Southcentral through tomorrow. Strong southeasterly flow will result in downsloping, dry conditions for much of the western Kenai Peninsula north through Anchorage and much of the Mat-Su Valley. However, this second system will bring rain a bit farther north than the previous, with locations along the Prince William Sound expected to receive periods of moderate to locally heavy rain (high elevation snow) throughout much of the weekend. As this front pushes into the area, a strengthening pressure gradient will also allow strong southeast gap winds to increase in intensity through tomorrow, particularly out of the Turnagain Arm and Knik Arms and Copper River Basin. A few higher gusts are also possible up on the Anchorage Hillside. Temperatures will remain near climatological averages, with highs in the 50s for most of the region and lows in the mid/upper 30s to low 40s. The associated large upper level low with this system crosses the Alaska Peninsula into the Gulf later on Sunday, with a weak ridge building over interior Alaska. When combined with some weak upper level shortwaves and marginal instability, a few weak/light convective showers and/or thunderstorms may develop along the foothills of the Wrangell Mountains/Alaska Range in the northern Copper River Basin late Sunday afternoon into Sunday evening. -ME && .SHORT TERM FORECAST SOUTHWEST ALASKA, BERING SEA AND ALEUTIANS (Days 1 through 3)... Rain, snow and windy conditions to the Aleutians and Southwest Alaska through the weekend. A Bering low will move in a mostly westward direction reaching just south of the Pribilofs overnight and Bristol Bay late tomorrow morning. As the low`s front progresses northeastward this evening, today`s rain and mix of rain and snow are expected to change over to all snow showers as temperatures drop overnight. This switch to snow is aided by the low`s placement just east of the Pribilofs by mid-morning tomorrow, continued cool 850mb temperatures and cold northwesterly air flowing into the region. Widespread light snowfall accumulations in the AK Pen, Eastern Aleutians and along the Southwest coast are possible. However, the precipitation will switch to a more rain/snow mix to rain quickly through the day tomorrow as temperatures rise. Cooler northwesterly to northerly flow will keep the precipitation in the Aleutians mainly a rain/snow mix this weekend. Winds in the Central Aleutians will remain strong into tomorrow afternoon before slowly decreasing. Northerly to northwesterly winds tomorrow evening and Sunday will bring continued cooler conditions to the northern side of the Aleutians, the AK Pen and Southwest Alaska as the aforementioned Bering low crosses into the North Pacific. Freezing spray returns for this weekend in response to the northerly and northwesterly wind flow. -DJ && .LONG TERM FORECAST (Days 4 through 7: Tuesday through Friday)... The upper level closed low near St Matthew Island weakens slowly and begins to move to the Eastern Aleutians and Alaska Peninsula before stalling briefly near Kodiak Island through the forecast period. The broad trough over the Bering makes inroads over most of Mainland Alaska with the jetstream support and North Pacific energy along the Southern portions continuing. Model confidence becomes more uncertain through the weekend with a number of troughs rotating through the pattern. The next significant weather producer moves over the Western Aleutians beginning Wednesday night as a North Pacific low and front moves across to the Eastern Aleutians by the weekend. Overall breezy conditions linger across the Aleutians and AKPEN through midweek, becoming gustier Wednesday night in the West, and spreading to the Eastern Aleutians for Friday. Gale force winds across the Southern edges of the low remain South of the Western Aleutians Wednesday and Thursday before diminishing. Rain spreads over the Aleutians through the forecast. Above average rainfall is expected to spread into Southwest Alaska, over the AKPEN into Cook Inlet and Kodiak Island for Wednesday and extends along the Eastern Kenai Peninsula across Prince William Sound to the Canadian Border. Heaviest precipitation will occur in the coastal zones, with lesser amounts spreading inland through Friday. -Kutz && .AVIATION... PANC...VFR conditions will persist. Confidence is higher today that the southeasterly Turnagain Arm wind will reach the ANC airport by late evening today.. However, the forecast challenge will be with regards to timing. The stronger southeasterly winds aloft have been staying in the 4000 to 5000 ft mountain top level and are expected to remain near this and not make it down to 2000 ft for true low level wind shear. && $$