Short Term Forecast Southcentral Alaska
A complex upper-level weather pattern will persist over the region through early next week, with the longwave trough extending from the eastern Bering across the AKPen and into the North Pacific. Multiple shortwaves will rotate around a developing upper-level low over the AKPen today, allowing a surface trough south of Kodiak Island to remain nearly stationary through this evening before finally weakening and drifting south tonight. Kodiak Island will remain primarily on the cold side of this trough, with northwesterly flow aloft. As such, the primary precipitation type will fall in the form of snow. although enough warmer air off the Gulf may allow some rain to mix in from time to time this afternoon for communities along the northern and eastern coasts. A Winter Weather Advisory remains in effect through Saturday evening.
Elsewhere, light showers move across the northern Gulf coast this morning, with an isolated shower possible along the southern Kenai Peninsula. The rest of Southcentral will remain dry, albeit with some cloud cover, as the low-level flow becomes northerly.
By Saturday, the upper-level trough over the AKPen will dig south bringing a shortwave and surface low currently over the far southeastern Gulf northwest into the central Gulf. It's warm front will sweep east to west across the Southcentral coast with a cold northerly flow out ahead of it and a warmer easterly flow in its wake. Expect light snow along with an increase in northeasterly winds for Thompson Pass by Saturday afternoon. By Saturday evening, snow will develop over the Kenai Peninsula, eventually spilling over the coastal mountains and across the western Kenai, Anchorage Bowl, and Mat-Su valleys by Saturday night. The snow could be heavy at times for the eastern Kenai Peninsula with 6 to 12" of snow not out of the question from Girdwood and Portage to Primrose with lesser amounts for Whittier and Seward. For Anchorage, 2 to 5" of snow is likely; however, there is still some uncertainty as to the exact track and timing. Any faster and farther south movement of the front will lower snow totals for the Anchorage Bowl. As the front moves over the Kenai Peninsula and drifts south Sunday, a warmer, easterly flow will advect in from Prince William Sound. Snow will likely change quickly to rain for coastal areas, but could linger as a wintry mix of snow, rain, and freezing rain for higher elevations of the Seward Highway. Snow may also end as a brief period of freezing rain from Anchorage to Kenai as the warmer air moves over the coastal mountains. One other area of concern will be around Homer, particularly the Homer Bluffs. Here, snow could linger through Sunday as the front stalls and colder air remains in place. There is greater uncertainty here as to how much cold air holds on. However, if it does remain colder across the southwestern Kenai Peninsula, snow totals could reach 3 to 6" from Ninilchik to Homer and Seldovia with up to 10" for the bluffs and Diamond Ridge.
.SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS (Days 1 through 3).
Broad northwesterly flow continues across the eastern Bering Sea, and is still yielding small craft gap winds for the Alaska Peninsula, particularly near Chignik and Wide Bay. These winds are on track to increase across the Alaska Peninsula, and out of the southern gaps and passes, through today and into the weekend. Chance for freezing fog early this morning for the Kuskokwim Delta and Kuskokwim Delta Coast. There will be some degree of an onshore wind component, so indications are this will be mostly advection fog from the Bering.
By late this morning, stronger southwesterly winds will pick up along the western Aleutians as a new low pressure system arrives to the Bering Sea. This system will mostly be a rainmaker for the Aleutians and Pribilof Islands with some snow on the front's leading edge. By Saturday morning, the low pressure system will make it's way into the central Bering, spreading westerly gales across the Aleutians, including Adak/Atka at the time. By Sunday morning, it is expected that the system will pivot, shifting southward and pulling colder air down along it's western periphery. As the low center dives south over the Pribilofs and eventually the eastern Aleutians, gusty winds are expected to blow through the Aleutians between Unalaska and Atka.