Area Forecast Discussion
Issued by NWS Anchorage, AK
Issued by NWS Anchorage, AK
521 FXAK68 PAFC 251316 AFDAFC Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 516 AM AKDT Sat May 25 2024 .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3)... Warmer and drier conditions are on deck for southcentral Alaska. An area of low pressure in the Gulf of Alaska will continue shifting southward today, resulting in precipitation gradually diminishing north to south. Breaks in cloud cover in conjunction with warmer boundary layer temps will result in surface temperatures warming into the upper 50s to lower 60s for most of lower elevation areas. These warmer conditions will yield some modest instability... resulting in showers developing across the Copper River Basin, Talkeetnas, and perhaps the Mat-Su Valley. An isolated lightning strike or two from a particularly strong shower cannot be ruled out. Southwesterly storm motion combined with upper-level support from a shortwave dropping south across the Alaska Range may allow for some rain showers to push into Anchorage and the western Kenai late Saturday evening into the overnight hours. Then, an upper-level low dropping from south of the North Slope will interact with the low lingering over the Gulf and one or more easterly shortwaves tracking in from Yukon. This produces a fairly uncertain forecast for Sunday and beyond, though the combination of features will provide support for rain showers and likely some steadier rainfall at times nudging into the easternmost portions of the forecast area as early as Saturday night. These precipitation features will propagate generally east to west, with the most likely areas to see over a tenth of an inch of rainfall in the Copper River Basin. However, there is moderate potential for this heavier rain to reach the western half of Southcentral late Sunday and heading into next week. Regardless, expect continued generally cool and cloudy weather with the occasional break of sun as well as the occasional shower. -Brown/Quesada && .SHORT TERM FORECAST SOUTHWEST ALASKA, THE BERING SEA AND THE ALEUTIANS (Days 1 through 3)... An elongated trough remains over the Bering this morning with an upper low, currently stretched from Bristol Bay into Kodiak Island, to exit southwest Alaska and move into the northern Gulf through this afternoon. Ultimately, this will see what had been persistent shower activity over Southwest come to an end. Later this afternoon a shortwave trough moves from the Seward Peninsula into the Western Alaska Range and Alaska Peninsula. With shower activity expected to gradually clear throughout the day, models are hinting at least some instability developing. Wet thunderstorm potential will not be zero as a result. MUCAPE of roughly 300 J/kg and total/totals of ranging from 40 to 50 are present on the NAM across the eastern Kuskokwim Delta, coincident with the passage of the aforementioned shortwave trough. Thus, a isolated wet thunderstorms may be possible in the late afternoon and early evening hours. Coverage of any thunderstorm activity should be limited, with activity propagating southwestward along the western side of the Kuskokwim Mountains through the evening hours. With the departure of the upper low over Southwest, weak northerly flow will become more prominent over both Southwest and the Bering the next couple of days. Sunday sees the arrival of a front into the Western and Central Aleutians, which will signal an increase in showers over the western half of the Aleutian Chain. The front weakens late Monday as it reaches the Eastern Aleutians, but scattered shower activity will likely persist for portions of the southern Bering. New shortwave activity along the front may reinvigorate winds and showers as the front moves into Southwest Alaska Tuesday morning -BL && .LONG TERM FORECAST (Days 4 through 7) Tuesday through Friday... The long term begins Tuesday with weak deformation and troughing remaining over Southcentral and a transient ridge moving from the AKPen and eastern Aleutians toward Southwest Alaska. The weak troughing over Southcentral will lend to continued shower activity across the region, mainly across the mountains and interior portions of Southcentral. The ridge continues east for Wednesday, helping bring a temporary reprieve to the extensive cloud cover and shower activity. However, the ridge quickly moves to the Alaska Panhandle as the upper-level trough, anchored by an upper- level low and associated surface low, reestablishes itself over the eastern Bering and Aleutians by late Wednesday. The result will be a return to widespread cloud cover and precipitation moving from the AKPen Wednesday afternoon across almost all of the Southern Mainland through Thursday. The broad long-wave trough remains in place with continued unsettled weather and cooler temperatures through the end of the week and into the start of next weekend. - TM && .AVIATION... PANC...High MVFR to VFR conditions will persist throughout the TAF period. Ceilings could remain at or below the 5000 ft threshold for much of the morning, but this deck will likely scatter/lift out by the afternoon. A short period of southeast winds is again possible as winds bend into the terminal from the Turnagain Arm, but the duration and intensity will likely be weaker compared to yesterday. && $$