textproduct: Anchorage

SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3)

The upper level ridge has build back over Southcentral Alaska for today. There remain some mid and high level clouds riding over the top of the ridge, but there should be plenty of sunny periods and widespread warm temperatures today. That is except for Kodiak Island where a stationary front continues to bring southeasterly flow off the Gulf resulting in rain and fog for the eastern side of the Island.

The warm conditions and fact that the ridge is not overly strong means that the atmosphere is moderately unstable today. Though there remains plenty of low level moisture for showers and thunderstorms, there is not much lift in the lower levels to initiate much convection in the valley areas. The mountains, especially the Alaska Range, Talkeetna Mountains and Wrangells, should provide enough elevated heating to produce some afternoon and evening showers and isolated thunderstorms.

The ridge will begin to break down on Saturday with and upper level wave tracking up Cook Inlet from the southwest and another one attempting to clip the northeastern part of the Copper River Basin from the Interior. This will keep the instability and afternoon convection potential to the middle and northern parts of the Susitna Valley and Copper Basin for Saturday. This should also cause temperatures to not be as warm on Saturday as they will be today.

Saturday night into Sunday, a pattern shift will take place as a strong low moves over Bristol Bay, driving a front into Southcentral. The front will bring rainfall into Kodiak Island and Coastal Southcentral Saturday night with the rain spreading into more protected areas such as Anchorage and the Susitna Valley on Sunday. The Copper River Basin, however, will remain drier at this point. This front will also increase the gap winds on Sunday, especially for the usual suspects: Turnagain Arm, the Knik River Valley and along the Copper River.

LONG TERM FORECAST (Days 4 through 7: Sunday through Wednesday)

By Monday morning, there is general agreement a ridge will be over the Alcan border into the Alaska Panhandle while a vertically stacked low will be over the Y-K Delta with its front over the northern Gulf and southern Southcentral. By this point, rainfall will likely be ongoing for much of Southwest/northern AKPen and Southcentral west of the Chugach and Talkeetna Mountains/Prince William Sound. This rainfall may be heavy for Southwest, the Susitna Valley, and the northern Gulf Coast. The front, as well as shortwaves rotating around the low, will push the ridge further into Canada on Monday. Any remaining areas with warm temperatures will begin a cooling trend on Monday. The Copper River Basin may still see high temps in the 70s if frontal progression is slow enough to keep the ridge close, but all other places will only top out in the mid to upper 60s. Rainfall progresses eastward to coastal locations east of Prince William Sound on Monday as the front moves onshore. Winds offshore the northern Gulf Coast may be up to gale- force Monday morning.

Though models diverge with progression of the low after Monday (some maintain it as a low over the Seward Peninsula, others open the low up into a trough), the general pattern looks to remain wet through the week for both Southwest and Southcentral Alaska as shortwaves continue to rotate around into southern Alaska. Heaviest precip will likely be along the western Alaska Range into the Susitna Valley on Tuesday and the northern Gulf Coast through Wednesday. Temperatures will also continue to cool throughout the week.

For the Bering, Aleutians, and southern AKPen, shortwaves rotating around the low to the north will likely maintain overcast skies with occasional showers through the week.

-PA

AVIATION

PANC...VFR conditions and light winds will persist through much of the period. By Saturday morning, a frontal system pushes into the area which will increase cloud coverage and lower ceilings.