textproduct: Anchorage

SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3)

Ridging remains over Southcentral Alaska today, leading to warm temperatures into the mid 70s over inland areas, light winds, and mostly sunny skies to prevail. There is sufficient moisture for low chances (~10%) for isolated thunderstorms over the Susitna Valley this afternoon, but the lack of lift due to the ridging will make it difficult for storms to form. Most thunderstorms, if they form, will be relegated to the mountain ranges and the slopes.

The ridge will be forced eastward on Saturday due to troughing pushing in from the west. Compared to yesterday, this is moving in faster and will prevent a shortwave from the interior from dropping down as much as previously thought. This means that chances for thunderstorms over the Copper River Basin are markedly decreased from yesterday for both their extent and number. Most thunderstorms will develop over higher elevations of the Alaska Range and the Talkeetna Mountains. The Susitna Valley could also see a few isolated thunderstorms before the next front moves in.

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 for the usual suspects: Turnagain Arm, the Knik River Valley and along the Copper River. By Monday, rainfall and gusty winds will begin tapering off, but southwest flow will allow for continued chances for rainfall for the Kenai Peninsula, Anchorage, and the Mat-Su.

-JAR/EZ

LONG TERM FORECAST (Days 4 through 7: Tuesday through Friday)

By Tuesday morning, there is general agreement of a vertically stacked low being over the Lower Yukon Valley. Troughing extends down through the Aleutians, with the most significant shortwave outside of the low being over the western Aleutian Chain. Models hint at shortwaves continuing to rotate around the low as it continues northward into the Interior. This will maintain chances for precipitation for much of the southern Mainland Tuesday. Specific timing of these waves is unknown, but the heaviest precipitation is expected to fall along coastal regions of the Northern Gulf Coast/Prince William Sound and along the Alaska Range in the western Susitna Valley. Out west, the Aleutians and Bering likely see showers Tuesday as the shortwave moves east. The shortwave over the western Aleutians becomes a closed low over the eastern Aleutians by Tuesday evening. This looks to pull additional moisture in and bring another round of rain for the eastern Aleutians, Southern AKPen, and Kodiak Island Tuesday night through Wednesday. This low crosses the southern AKPen into the Gulf Wednesday morning and moves into the Alaska Panhandle on Thursday. As the low moves through the Gulf on Wednesday, rainfall will likely shift to the northern Gulf Coast east of Prince William Sound with some spilling over into interior locations of Southcentral. Models diverge with resolving certain surface features (mainly whether or not a surface low develops in the Gulf on Wednesday). If a surface low develops in the Gulf Wednesday, rainfall may be enhanced along the northern Gulf coast. Some southeast gap winds (Turnagain, Knik, and Copper River winds) may be enhanced as well on Wednesday. These details will become more clear in the coming days.

To the west of the lows, models diverge on solutions between zonal flow and attempts at a ridge building in the Bering with additional shortwaves traversing into the southern Mainland. Either pattern would support cooler temperatures and mostly overcast skies across much of southern Alaska and the Bering with continued chances for precipitation across the southern Mainland.

-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.