Area Forecast Discussion

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3: Today through Wednesday night)...

A series of shortwaves will propagate through Southcentral Alaska today into tonight in the southwesterly flow aloft. The first one is in the northeastern Copper River Basin and heading into the Yukon. This wave helped bring in the advisory-level snowfall to the southern slopes of the Alaska Range. With it moving out of the area that advisory has been canceled.

The second wave can be seen on satellite imagery early this morning over northern Cook Inlet. This is a weak wave and is mainly just bringing some mid to high level clouds with snow showers relegated to the Talkeetna and Chugach Mountains.

The third shortwave is entering southern Cook Inlet early this morning and is a much stronger wave. This is the shortwave that is expected to bring showers to the Kenai Peninsula by late morning and to Anchorage and the Mat-Su this afternoon. With the southerly surface winds persisting (though not as strong as yesterday), the precipitation type should mainly be rain. However, there is a chance for some snow to mix in this morning as well as in heavier showers. There is also the potential for small hail in these showers due to the low freezing level. The Anchorage ROAB showed a freezing level of 1100 ft at 3 AM, but this is expected to rise as the day progresses.

After this third shortwave moves through, the flow aloft will shift more westerly for Tuesday which should bring a few breaks in the clouds and less shower activity. However this will be short lived as an atmospheric river will bring a return to wet and windy conditions.

.SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS (Days 1 through 3: Today through Thursday morning)...

Rain and snow showers will persist today across the southwestern mainland as a series of upper-level disturbances moves in from the Bering Sea. The expectation is for continued showery precipitation across the area with westerly upslope enhancement along the Western Alaska Range and Aleutian Range. This activity will taper off through Tuesday morning as an upper-level shortwave ridge begins building into the southwest mainland by then. Despite the ridge moving in, expect another overcast day across Southwest for Tuesday.

Attention then quickly turns to the next significant Bering Sea system which is currently gathering strength just southeast of Shemya this morning. This system will deepen further tonight and Tuesday as it wraps in more cold air from Russia and remains nearly stationary between Adak and Amchitka through early Wednesday morning. As the system spins between Amchitka and Adak, multiple frontal systems will be sent northward and eastward. The first of which will be today through tonight with Adak and the Pribilofs seeing light rain with the gustiest winds remaining confined to Adak.

The second and more widespread frontal push of moisture will arrive with moderate to heavy rain Tuesday morning to Adak and Atka and will arrive to the Pribilofs and Nikolski/Unalaska/Akutan by late Tuesday morning to early Tuesday afternoon. By Tuesday afternoon, the storm strengthens to storm-force on the northern periphery of the system just west of the Pribilofs. Heavy rain moves to False Pass, King Cove, Cold Bay, and Sand Point by Tuesday evening. Moisture also makes its presence known across mainland Southwest Alaska also by Tuesday evening. The Kuskokwim Delta and Nunivak Island could see a period of snow at the onset of precipitation Tuesday evening before turning to rain overnight Tuesday as warm air and southerly flow advance northward. Heavy rain will not stay over the Alaska Peninsula too long as the moisture corridor shifts east to Kodiak Island by Wednesday morning with the Interior Kuskokwim Delta, Kuskokwim Valley, and Bristol Bay continuing to see light to moderate rain at times Wednesday morning through Wednesday evening.

The storm slowly pulls northeastward to the central Bering near the Pribilof Islands by Thursday morning. Additional cold air gets pulled southward into the western Bering from Russia on the backside of the storm. Rain/snow showers are a good bet for Shemya from Wednesday afternoon into Thursday morning as the unstable airmass moves overhead. The Pribilofs will contend with an additional round of rain or rain/snow mix Wednesday evening into Thursday morning as showery conditions also persist across mainland Southwest for that time period as well.

.LONG TERM FORECAST (Days 4 through 7: Thursday through Sunday)...

Unsettled conditions will likely persist across much of Alaska through the upcoming week. A low over the southern Bering Sea will move toward Nunivak Island by Thursday morning. South to southwesterly flow with gusts up to 40 mph will move across Kuskokwim Bay/Delta area. Concerns for coastal impacts is low due to shorefast ice and some added protection from the expansive ice flow over the eastern Bering Sea.

The accompanied front from the Bering low will move into the western Gulf of Alaska, drawing with it a relatively deeper surge of moisture. Coastal areas in the northern Gulf and Kodiak Island and higher elevations of the Alaska Range will likely see the most precipitation. Away from the coast, expect several days of mixed precipitation to continue, including rain at lower elevations and snow at higher elevations. Southeasterly flow will allow some downsloping to the west of the Chugach and Kenai Mountains.

Model agreement decreases significantly late in the week, though some semblance of a low continues to place a low in the southern Bering Sea with southerly flow persisting into Southcentral. It is probable that our overall pattern will not deviate much from what we are already seeing, however, the details should become clear with the timing of these key wind and precipitation features as we approach the mid to late week timeframe.

AVIATION

PANC...Gusty southerly winds will gradually diminish through the day today, with peak gusts decreasing from 30 to 20 kts through around 08Z. VFR conditions will likely prevail today, with only a slight chance of briefly dipping into MVFR conditions with passing showers this afternoon. Southerly winds will continue to diminish, remaining light through tomorrow morning.