Area Forecast Discussion
Issued by NWS Anchorage, AK
Issued by NWS Anchorage, AK
596 FXAK68 PAFC 090116 AFDAFC Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 516 PM AKDT Sat Jun 8 2024 .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3/Today through Tuesday night)... A broad longwave trough over the southern Gulf of Alaska will start to send multiple fronts over Southcentral starting tonight. The first front has been over the central Gulf, sending a line of very moist air over Kodiak Island throughout the day today and will continue to do so through the remainder of the weekend. The Flood Watch for the island is still in effect through late Sunday night for an additional 2-3 inches of rain still possible. A brief lull overnight will subside to another front passing over on Sunday, providing an additional round of heavier precipitation. As the current front over the Gulf moves over Southcentral tonight, gap winds near Turnagain Arm, Knik River Valley, and the Copper River Valley will quickly increase and persist through the overnight hours. A Special Weather Statement is out for the potential of gusty winds briefly bending into Anchorage this evening. The duration of this will be short lived as the energy of the frontal passage will be the main factor in turning the Turnagain Arm wind northward. Relatively cooler temperatures will move in over the region and last through at least Tuesday afternoon. Additionally, the multiple fronts moving northward from the trough in the Gulf will increase the potential for widespread showers over most of the southern portion of the forecast area as each day passes. Moving into Tuesday, the pattern begins to shift as the longwave trough slowly moves southwestward towards the North Pacific. As it does so, the orientation of the trough and a ridge building in from the North Slope and moving southward will cause most of its energy to move over Southcentral in the form of easterly waves. There are currently discrepancies from current model guidance in the intensity of the waves over the region Tuesday afternoon, so stay tuned for future updates as this system continues to develop. -BS && SHORT TERM FORECAST SOUTHWEST ALASKA, THE BERING SEA AND THE ALEUTIANS (Days 1 through 3: This afternoon through Tuesday afternoon)... Unsettled weather persists through the weekend as several lows merge southwest of Kodiak Island, sending pinwheeling upper level shortwaves across all but the Western Aleutian Islands and Bering Sea. One such wave will move through this afternoon and evening, with another arriving for Sunday. Rain will be more widespread, albeit light, with the wave moving through today. Meanwhile, winds will be the primary threat for tomorrow; we continue to expect gusts of 40-50 mph for interior Bristol Bay. Conditions improve from Monday through Tuesday as the low near Kodiak Island weakens and a ridge builds in from the west. The next system approaches the Western Aleutians Tuesday afternoon, heralding a return to more active weather after a spell of calmer conditions for the Western Aleutians/Bering. -KC && .LONG TERM FORECAST (Days 4 through 7)... Upper level ridging extends from northern Alaska into the Bering Sea by mid week, with two upper level lows on either side, one situated over the Western Aleutians and the other in the North Pacific. Multiple shortwaves will cycle around the Pacific low and move over Southcentral and portions of the Alaska Peninsula, bringing rounds of rainfall through at least Friday. High pressure dips south over Southcentral by next weekend which is likely to bring about drier conditions. The system developing out west will push its front across the Aleutians towards Southwest Alaska through next weekend. Areas of small craft to gale force winds are likely along the front as well as localized areas of heavy rainfall. There is decent model agreement initially but discrepancies quickly increase by next weekend. && .AVIATION... PANC...VFR conditions to persist. Mild northerly winds continue to filter into the terminal but the expectation remains for winds to increase in intensity through this evening while also transitioning to a southeasterly direction. From this morning`s discussion with a few updates, a pressure gradient between Anchorage and the Susitna Valley should be strong enough to briefly overcome a strong down-inlet pressure gradient developing out ahead of a strong trough moving into the Kenai Peninsula from the northern Gulf. Southeast gusts associated with a strong Turnagain Arm wind clipping west Anchorage as strong as 30 kts will be possible between 3z and 9z tonight. Winds bend away from the terminal briefly late tomorrow morning before returning in the afternoon with gusts closer to 15 knots. BL/SB && $$