Area Forecast Discussion
Issued by NWS Anchorage, AK
Issued by NWS Anchorage, AK
126 FXAK68 PAFC 160105 AFDAFC Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 505 PM AKDT Sat Jun 15 2024 .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3)... Only small changes to the forecast as we move into Sunday. High pressure over western Alaska will begin to retrograde west and northwest as an area of high pressure over interior Alaska drops southward over the Alaska Range and Copper River Basin. A weak upper low over the northern Gulf will pivot west and southwest through Sunday night, becoming an open wave trough over Kodiak Island by Monday morning. Warm temperatures and the chance for convection remain the biggest concerns the next few days across Southcentral. Saturday saw widespread upper 70s temperatures across Southcentral with lower 80s temperatures observed across the Susitna Valley and inland of Western Kenai Peninsula. This resulted in RH values down to 25% or lower for the Susitna Valley and also across the Copper River Basin. A lack of meaningful wind has precluded hot-dry-windy conditions, but showers and isolated thunderstorms will remain possible through the evening hours. A strong, but not severe, storm was noted near Cooper Landing earlier today with numerous lightning strikes noted on satellite. For Sunday, high pressure shifting over the Copper River Basin will see subsidence (sinking motion) and a stronger capping inversion (think stable layer of warmer air aloft). This will spell a break from precipitation over the Copper River Basin. The threat for convection will thus be confined to along and west of the Talkeetnas where high pressure is weaker, as well as further south into the Western Kenai Peninsula. Temperatures will be relatively cooler across the Mat-Su and Western Kenai Peninsula, with fewer locations reaching 80 degrees. Further east and beneath high pressure, the Copper River Basin is more likely to see a greater number of locations warm into the upper 70s, a small change from Sunday. Monday continues the cooling trend as high pressure breaks down over the Copper River Basin and a trough lifts from the western Gulf into the Susitna Valley. Isolated to scattered showers and thunderstorms will again be possible during the afternoon and evening hours. && .SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS (Days 1 through 3)... An upper ridge remains over interior Alaska with weak upper level shortwaves supporting thunderstorm activity across Southwest Alaska, particularly along the western Alaska Range, through late this evening. Convective activity is expected again across these areas Sunday afternoon and evening. By Monday, a relatively stronger easterly shortwave moves through supporting the potential for more widespread thunderstorms extending from the western Alaska Range through the Kuskokwim Delta. A front and associated upper level low sitting over the Central Aleutians will continue to bring rounds of rain showers and small craft winds to the Western/Central Aleutians through the rest of this weekend. Rain chances also return to the eastern Aleutians Monday as a weak surface low forms south of the Aleutian Chain. -ME && .LONG TERM FORECAST (Days 4 through 7: Wednesday through Saturday)... A broad upper-level low extending along and south of the Aleutian Islands and Alaska Peninsula on Wednesday shifts eastward through the end of the week. Rainy conditions associated with a weak front shift from the Alaska Peninsula, Kodiak Island, and Bristol Bay into the Gulf of Alaska for Thursday. A series of shortwave troughs embedded in the broad upper low lift into southern mainland Alaska and then rotate westward on Thursday and Friday, bringing a slight cooldown and wetter conditions. Increased lift afforded by these shortwaves will lead to areas of more widespread, steadier rainfall across portions of Southcentral and Southwest Alaska. For Friday, a North Pacific low passes south of the Gulf of Alaska, approaching Southeast Alaska/Haida Gwaii by Saturday. The low pressure draws theta-e ridging southward from Interior Alaska, allowing a return to warmer weather and thunderstorm potential for the southern mainland next weekend. Out west, surface high pressure over the Bering Sea will likely support widespread fog and low stratus across the western and central Bering on Wednesday and Thursday. A North Pacific low, potentially gale-force, begins to push into the western/central Aleutians for Friday, scouring out some of the fog, but bringing windier, wetter conditions. Heading into the weekend, the low progresses north and east, spreading rain and gusty southeasterly winds potentially as far as the Alaska Peninsula. Quesada && .AVIATION... PANC...VFR conditions and light winds will generally prevail throughout the TAF period. Showers are expected to develop and move off the mountains through the afternoon and evening hours today. Can`t rule out a thunderstorm as well, but probability remains too low for TAF inclusion at this point. Showers will again develop on Sunday with coverage similar or a bit less than that of today. && $$