textproduct: Anchorage

SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3)

Discussion:

Several key features in place today that will come into play over the next several days. Currently, high pressure remains over the Bering Sea with another stout ridge entrenched over much of the western Canadian Territories. Various low pressure systems are positioned around and in between these areas of high pressure. Several shortwaves have been transiting across the Bering Strait and northern Alaska, helping to give a bit of lift to afternoon convection over the past several days. A weak trough has stalled over the Copper Basin where convection was able to initiate rather early today resulting in numerous pulse-type showers and isolated thunderstorms. A shortwave moving in from the west may help to initiate a bit more convection across the Northern Susitna Valley and along the western slopes of the Chugach and Kenai Mountains this afternoon. Steering flow remains weak so any convective shower will result in some brief heavy downpours. The low stratus and fog that worked its way up the Cook Inlet and Prince William Sound overnight and early this morning is starting to mix out this afternoon. However, the nearly saturated marine layer is expected to fill back in later tonight through tomorrow morning.

Further south, a low moving up from the North Pacific into the southwestern Gulf will bring gale force winds as the front lifts across the Gulf. Gusty east to northeast winds are expected for Kodiak Island with periods of moderate to heavy rainfall from Friday afternoon through late Saturday. The heaviest rainfall will accompany the front as it quickly lifts through resulting in a general 1-2 inches for many locations across Kodiak Island, though some isolated 2-3 inches are possible especially for areas of enhanced upslope flow. This low will track to the south of Kodiak Island before stalling and weakening near Sand Point.

The eastern Kenai Peninsula and northern Gulf coast will also see widespread rainfall as the front lifts through. Another low will quickly move up along the eastern periphery of the aforementioned low...quickly deepening before it lifts towards the eastern Kenai Peninsula and weakens. This low will bring a modest surge of moisture north with another round of moderate to heavy rainfall for the northern Gulf and Prince William Sound.

- PP

LONG TERM FORECAST (Days 4 through 7/Monday through Thursday)

Starting early next week, there will be an upper level trough over mainland Alaska and the Gulf of Alaska/Kodiak Island, with a ridge upstream over the Bering Sea/Aleutians. This will be the tail end of wet and windy weather across much of southern AK and bordering coastal waters, with showers and clouds lingering across much of the region. As we continue through the week, the high amplitude trough will exit eastward to Canada, leaving a weak flow regime with weak embedded features. The subtropical jetstream over the North Pacific will also weaken through the week, with a noted absence of strong storm systems. Thus, the pattern looks very "summer-like", with daily afternoon/evening showers and thunderstorms over southern AK driven by surface heating and resulting instability and generally light winds across much of the Aleutian, Gulf and southern AK coastal waters. While the week will start out cloudy, expect increasing sunshine and warming temperatures through the week. High pressure will remain centered across the southern Bering and Aleutians, so widespread low clouds and fog will be common.

-SEB

AVIATION

PANC...Up inlet winds will continue to bring a marine layer to the Terminal for the next 18 hours or so. The stratus has burned off but is expected again early Friday morning and will return conditions to IFR. Showers are likely again over the mountains but with no steering flow they will remain over the Front Range.