textproduct: Fairbanks

SYNOPSIS

Spring has finally arrived across most of Northern Alaska due to southerly flow between an upper level ridge building across western Canada and low pressure across the Bering Sea. A frontal system lifting north across the Alaska Range this evening brings potential for a light wintry mix, including freezing rain potential to localized areas including Fort Yukon by Saturday morning. A strong low crosses the Aleutians into the southern Bering Sea on Sunday morning bringing mainly rain with higher elevation snow to the West Coast and Western Interior. This system also brings easterly winds up to 45 mph late Saturday night through Sunday, but blowing snow is not expected. In summary, multiple disturbances lifting north across the state focus areas of mainly rain/snow showers through the weekend, but total precipitation amounts are generally light.

KEY WEATHER MESSAGES

Central and Eastern Interior... - Southerly gap wind gusts gradually diminish this evening through tonight with another round of southerly gap winds expected on Sunday.

- A warm front brings a light wintry mix of rain, snow, and freezing rain to portions of the interior Friday night. Freezing rain is most likely in the vicinity of Fort Yukon, but temperatures warm quickly on Saturday limiting impacts.

- A persistent Chinook keeps temperatures near to above average. High temperatures mainly in the 50s continue across the Interior Valleys through the end of April with even warmer temperatures possible by early May.

West Coast and Western Interior... - Another Bering Sea low brings easterly winds gusting up to 45 mph to the YK Delta Coast, southern Seward Peninsula, and St. Lawrence Island late Saturday night before subsiding Sunday night.

- There is potential for an ice shove (ivu) on St. Lawrence Island, especially across Maknik Lagoon.

- Active weather continues into next week with multiple rounds of mainly rain showers, except for a band of steady precip on Sunday across the YK Delta. Snow levels stay near 1000 ft except for brief periods overnight.

- High temperatures warm into the 40s for the Western Interior and upper 30s along the coastline through early next week.

North Slope and Brooks Range... - Light snow is likely across the western and central Brooks Range this afternoon through Saturday evening with up to 3 inches of accum.

- East winds up to 35 mph continue near Point Lay through Saturday then return on Monday. Southerly winds up to 30 mph are possible through the Brooks Range Passes on Saturday.

- High temperatures gradually warm into the 20s along the Arctic Coast and Plains by Sunday and overnight lows warming into teens/20s.

FORECAST ANALYSIS AND DISCUSSION

The large scale pattern doesn't change much throughout the forecast period with low pressure over the Bering and high pressure over western Canada. A weakening ~999 mb low pressure is spinning across the northern Bering Sea with a ~1030 mb surface ridge extends north toward Juneau. This pressure gradient allows gusty southerly winds to continue through Alaska Range Passes, especially Isabel Pass where gusts up to 60 mph gradually diminish below 40 mph Sunday morning. Additionally, a warm front embedded within the southerly flow lifts north across the Alaska Range this evening and brings a wintry mix to northern portions of the interior late tonight. Accumulations appear minor, but the mixture of snow and freezing rain justified issuing an SPS for the Yukon Flats, including Fort Yukon. A similar wintry mix is possible along the Kotzebue Sound coastline, but accumulations are expected to be spottier there. By the time the front reaches the Brooks Range snow is expected to be the dominant p-type with up to about 4 inches of wet snow on south facing slopes above 1500-2000 ft across the west-central mountains.

A much stronger sub-960 mb surface low spins into the southern Bering Sea Saturday night that then gradually weakens across the central Bering Sea early next week. This system sends a fairly strong occluded front northeast toward the YK Delta late Saturday night that reaches the Seward Peninsula by Sunday evening. Easterly winds increase to around 45 mph associated with this frontal system, especially along the coastline. The front brings a 6-9 hour period of moderate to heavy precipitation rates to the YK Delta and p-types are relatively low confidence due to marginal boundary layer temperatures that could go either way, which should also mitigate the blowing snow potential. Farther north, this front lifts north across St. Lawrence Island on Sunday and southeasterly winds gusting up to 45 mph could result in ice shove potential across Maknik Lagoon. The southwest cape up to Powooilak Camp is also exposed, but sea ice is further offshore and may not be able to reach the coast before winds weaken. The front weakens on Monday while shifting inland resulting in more showery precipitation. An energetic shortwave pivoting around the Bering Sea low shifts north on Tuesday resulting in a strong frontal boundary across the interior and the potential for the first lightning strikes of the season.

EXTENDED FORECAST DAYS 4-7

Not much has changed in regards to the extended forecast. Models remain in good agreement with the low in the Bering continuing to spin in place through the middle parts of next week. Meanwhile, ridging is expected to amplify over the Al-Can boarder. This would continue to support the southerly flow pattern over a good portion of the state. This would set up for good moisture transport across the Central Interior/West Coast and gusty winds through the Alaska Range. Models are showing the potential for a more apparent shortwave to work its way over the Alaska Range sometime Tuesday afternoon/evening. There is still some slight disagreement in regards to timing. In addition, the trough over the Bering is looking to shift NE by the end of next week and setting up the potential for a negatively tilted ridge extending from the Alaska Peninsula to the Brooks Range. This would continue to support the seasonal change into Spring.

Coastal Hazard Potential Days 3 and 4...None

AFG WATCHES/WARNINGS/ADVISORIES

AK...Wind Advisory for AKZ837-849. PK...None.