textproduct: Anchorage

SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3)

Radar returns this afternoon show a band of precipitation moving westward towards the northern Cook Inlet region from the Prince William Sound, with some of the precipitation also moving northward towards the Matanuska Valley. With cold air aloft and above freezing temperatures across much of the northern Cook Inlet region and Valley locations, precipitation type is largely going to depend on intensity of showers that move across this stretch of Southcentral. During heavier precipitation rates, expect a rain/snow mix or all snow until showers begin to taper, whereas light precipitation should mostly be in the form of rain. 500 mb heights and vorticity analysis shows that the base of a neutrally tilted trough axis is moving over Southcentral now, and until this feature clears the area later this evening and overnight, expect periods of showery conditions to continue. The GFS deterministic runs continue to consistently show a slower progression of this trough axis lifting out of the region and more over the Copper River Basin by midnight or so. In the wake of the trough Friday morning, clearing skies, light winds, and radiational cooling will allow for temperatures to fall into the mid to upper 20s for most of our population centers from Anchorage to the Matanuska and Susitna Valleys. One caveat is that if we do see patchy fog or freezing fog forming for some of the valley locations Friday morning, overnight low temperatures may be slightly warmer than what we are advertising, but there is high confidence (80 percent) that much of Southcentral will see its first hard freeze of the season. Depending on how much precipitation falls today, be on the lookout for areas of patchy black ice for your Friday morning commute.

Looking farther eastward and stepping forward in time, the upper trough will continue to bring showers to the Copper Valley through around noon to 3PM Friday as it lifts out of the region. To the south, a high end small craft to gale force complex low pressure system enters the gulf Friday afternoon. This will first affect Kodiak Island with northeasterly gales and a round of rainfall through the weekend. A large swath of precipitation associated with this system lifts towards the northern Gulf coast through Saturday afternoon. There is still a bit of spread in the models between timing of precipitation arrival to the Gulf coast, but there is much higher confidence (70 to 80 percent) in an easterly gale force barrier jet setting up along the northern Gulf coast, and gales located in the southern Cook Inlet and Shelikof Strait as this system draws closer to the coast Saturday morning through Saturday afternoon. Coastal ridging will set up shop along the Gulf coast prior to this system's arrival, which in turn will most likely increase gap winds for the Turnagain Arm, Knik River Valley, and Copper River Basin. Stay tuned.

-AM

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

The seasonably active weather pattern continues through the long term period, beginning with broad troughing spanning across the eastern Bering Sea to the southern Mainland early next week. A weakening surface low shifts into the Gulf Monday into Tuesday, with southerly flow and ample moisture keeping the eastern Kenai and northern Gulf coast wet through midweek as the low slowly tracks east across the northern Gulf. For the Alaska Peninsula, Bristol Bay, and inland Southcentral locations, expect unsettled and showery weather to continue through early next week as weak shortwaves rotate through the upper level flow. Additionally, gusty northerly winds enhanced by cold air advection on the back side of the low will be possible across the eastern Aleutian Islands and AKPen, especially through favored gaps and passes.

By mid to late next week, a potentially more impactful storm is expected across the Bering as the next Kamchatka shortwave interacts with tropical energy lifting north out of the North Pacific. Widespread rainfall and strengthening winds are expected to reach the western Bering and Aleutian Islands Wednesday into Thursday before spreading east across the rest of the Bering and Aleutian Chain through the remainder of the long term period. Significant model spread remains in the evolution of this storm as the two systems interact in the North Pacific and Bering Sea, but strong winds and periods of heavy rain are beginning to look increasingly likely by late next week across the Bering and Aleutians.

AVIATION

PANC...MVFR with rain and snow showers will gradually taper off this afternoon. Confidence is medium-low for the timing of each shower and when the precipitation ultimately ends. Skies should start to clear late, after 04Z, though freezing fog may develop overnight. Otherwise, mostly sunny skies and north/northeast winds will prevail Friday afternoon through Friday night.