textproduct: Anchorage

SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3)

KEY MESSAGES:

1) A Gulf of Alaska low and an elongated surface trough will bring snow, rain and wind to Southcentral today through Sunday.

2) Blizzard conditions on Kodiak Island are expected from today through 6pm Friday evening.

3) Many watches and warnings are in effect today through Sunday across Southcentral Alaska.

Overshadowed by a Bering Sea low, a broad north Pacific trough with multiple embedded shortwaves that will lift north into the Gulf this evening and into the remainder of Southcentral over the weekend. This will bring snow to the entire region. It is important to note that as the low moves across the Interior, a deformation zone will form from the Kenai Peninsula northward to the Mat-Su Valley that would lead to localized increased snowfall amounts. Forecasting this area of localized snowfall accumulation is difficult given its mesoscale forces at play. However, current thinking is that it will setup on Saturday after the accumulating snow has already begun to fall. Many watches and warning across Southcentral have been issued to coincide with the overall snow this weekend.

Kodiak Island and the City of Kodiak will experience blizzard conditions late this evening through late Friday evening as the Gulf of Alaska low with its associate front moves toward Prince William Sound. There has been a delay in the onset of these snowy and windy conditions and a decrease in snow amounts for the City of Kodiak from the last forecast package. The changes were the overall slowness in arrival time of the precipitation and a longer period of rain will mix into the snow overnight Friday.

By Friday afternoon, widespread snow is expected for the Prince William Sound communities. Forecast confidence is highest for the eastern Sound and southern Copper Basin receiving the bulk of the precipitation from the warm front.

-DJ/CJ

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

Bitterly cold air temperatures and wind chills continue across Southwest Alaska.

The large low south of the Aleutians is continuing to produce snow showers, gusty winds, and cold temperatures across the Bering Sea and Aleutian Chain. Blizzard or near blizzard conditions are expected to continue over the Central Aleutians through this morning, gradually diminishing through this afternoon. Additionally, periods of blowing snow is possible across the Eastern Aleutians, including Unalaska today, producing reduced visibilities at times.

An upper level trough digging southward along the Southwest Alaska coast is producing a corridor of gusty winds for portions of the Southwest, streaming southwestward out of the Kuskokwim Delta coast and the Bristol Bay region and across the eastern Bering. Areas of blowing/drifting snow is expected which may result in periods of reduced visibilities. The Winter Weather Advisory for blowing snow remains in effect through late tonight. Winds should begin to diminish through Saturday morning and the blowing snow conditions are expected to subside.

Areas of extreme freezing spray expected to continue along the ice edge through early Saturday morning.

By the weekend, cold temperatures and northerly winds will remain over almost the entirety of Southwest Alaska, Bering Sea, and Aleutian Chain.

LONG TERM FORECAST (Days 4 through 7: Sunday through Wednesday)

The active weather pattern is expected to continue for the first half of next week. The upper level low will still be over the Interior and southwest Alaska on Sunday, keeping Southwest Alaska entrenched in the cold with part of Southcentral still being in lingering snow on the tail end of the weekend system. The upper level trough will not move a lot through Monday, but what does change on Tuesday is that the trough will edge westward as a strong low moves into the Gulf of Alaska from the south. There is a reasonable degree of uncertainty as to the exact strength and track, but what looks likely is that this low will end up moving into Prince William Sound or to the east of it. This will keep Southcentral in the snow with only Cordova in a position to see potential for a switch to rain from the snow. This system has the potential to produce strong winds and heavy snowfall for coastal regions including the coastal mountains Tuesday and Wednesday.

High surface pressure will remain centered over the Western Bering Sea through the period. With the upper level trough remaining over Southwest Alaska and the Bering Sea, this will keep Southwest Alaska as well as the Bering Sea/Aleutians/AK Peninsula with cold temperatures and stiff northerly winds. While most of the precipitation will remain east of the Alaska/Aleutian Ranges, the Alaska Peninsula and eastern Aleutians have the potential for periods of heavy snow showers that develop off the ice edge and stream into those areas.

AVIATION

PANC...VFR conditions will persist through most of today. MVFR conditions could move in as early as this evening as a front moves across the Gulf and snow moves in from the from the east and southeast. More likely is for MVFR conditions to develop overnight tonight into Saturday morning. North to northeast winds will remain around 10 kts or a little greater today which could cause some instances of drifting snow. Towards then end of the TAF period Saturday morning, depending on how pressure gradients orient, there is the chance for southeast winds out of Turnagain Arm to clip the terminal before turning southerly to southwesterly late morning Saturday. There is also potential late tonight into Saturday morning for low-level windshear as the front moves overhead with surface winds remaining out of the north or northeast and winds 2000 feet above the surface out of the southeast.