Area Forecast Discussion
Issued by NWS Anchorage, AK
Issued by NWS Anchorage, AK
654 FXAK68 PAFC 280040 AFDAFC Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 440 PM AKDT Mon May 27 2024 .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3)... A broad trough over the Yukon today will move slowly westward over Alaska by mid-week. Satellite and radar show continued cloud cover and rain across much of the Copper River Basin this afternoon. Rain will persist overnight as northeasterly flow from the aforementioned trough continues over the region. The heaviest of the precipitation for the Copper River Basin will fall later this evening and into early tomorrow morning as weak shortwaves move through the area. Isolated rain showers are possible tomorrow north and west of a line from Tok to Glennallen to Valdez as the trough slowly moves eastward and the windflow becomes more northerly; steadier showers are expected east of this line through Wednesday with continued weak waves moving out of the Yukon. These waves could continue through mid-week as the low currently in Prince William Sound moves closer to shore reinforcing the northerly to northeasterly flow for Valdez to Cordova during that time. Periods of scattered rain showers through mid-week are possible in the Mat-Su Valley and Anchorage areas as northeast flow form the aforementioned trough and PWS low impact Southcentral Alaska. More widespread rain is expected Wednesday for Kodiak Island as a front and short-wave approach from the south. The forecast for Southcentral becomes more uncertain, with model differences in track of another short-wave out of the Yukon into Southcentral. There is potential for another round of steady rain across the Copper River Basin Wednesday, with showers out ahead of it over western portions of Southcentral. -DJ && .SHORT TERM FORECAST SOUTHWEST ALASKA, THE BERING SEA AND THE ALEUTIANS (Days 1 through 3)... Southwest Alaska is expected to remain dry through Tuesday as weak high pressure ridges inland from the eastern Bering. This will also maintain mild winds over the region through tomorrow. A broad front extends southeastward from the western Bering into the Eastern Aleutians. This front is bringing rain showers this afternoon to the eastern Aleutians with southeasterly winds gusting between 25 to 30 knots. Into Tuesday a surface low is forecast to develop along the front somewhere south of the Pribilofs. Enhanced southeasterly flow will become more prominent through the Alaska Peninsula with increased winds through gaps and passes. Across Southwest, a shortwave trough lifting out of the North Pacific will promote renewed shower chances from Bristol Bay into the Lower Kuskokwim Delta and Lower Kuskokwim Valley. While thunderstorm chances are less certain, it appears isolated wet thunderstorms will be possible with the an area of weak instability developing over the Middle Kuskokwim Valley late in the day. Any activity that does develop should get carried northwestward within broad southeasterly flow aloft. Shower activity and winds over the Alaska Peninsula should gradually diminish by Wednesday morning. The Aleutians and Southwest should experience below normal temperatures and general cloudiness while the low remains in place. By Wednesday afternoon a surface low over the Eastern Aleutians will begin to weaken and fall apart as the next system approaches the Western Aleutians from south of the Commander Islands. && .LONG TERM FORECAST (Days 4 through 7) Friday through Monday... The weekend opens with a decaying upper level low over the Northeast Pacific that gets absorbed by a Western Aleutian low as it moves across the Alaska Peninsula by Sunday. This second low tracks to the East-Southeast through Monday. A broad trough remains over most of the Bering and Southern Alaska through the forecast. Model agreement is relatively good, opening with a deterministic blend and transitioning to a one-half ensemble means by the beginning of next week. Most of the active weather continues across the Southern portions of the state. Southcentral Alaska stays under persistent Southeasterly flow, keeping a good mix of moisture moving inland to the Alaska Range. Showery precipitation will continue through the weekend. More active lows, fronts or troughs brings periods of rainfall across the Aleutians, Bering and AKPEN, and into Southwest Alaska. Northerly wind flow across the Western parts of the state maintains lower than normal surface temperatures. Only the Eastern Interior will see any warmer temperatures, with a upper level ridge angled over the Central and Northern areas. -Kutz && .AVIATION... PANC...VFR conditions will likely persist through the TAF period. With a ridge building overhead and weak upslope flow with southwesterly flow coming up Cook Inlet, ceilings will likely lower with loss of solar heating this evening. There is a small chance of MVFR ceilings overnight through Tuesday morning, though the more likely scenario is low end VFR ceilings. Expect a gradual lifting of ceilings during the day Tuesday with surface heating and a shift to easterly flow at mountain-top level. && $$