textproduct: Fairbanks

SYNOPSIS

Active weather will cause disruptions through the holiday week, as two systems bring moderate to heavy snowfall, gusty winds, and blowing snow to much of Northern Alaska. The first system is beginning to wind down this afternoon as it moves inland across the Western Interior and weakens as it runs into an area of high pressure over the Eastern Interior. By Tuesday, a more substantial system will begin to make its way to the West Coast. As it does, widespread moderate to heavy snow will again develop, first along the coast, before pushing east to the Northwest Interior through the day. By Tuesday night, light snow will make it into the Fairbanks North Star Borough with moderate to heavy snow at times developing across this region as the main front moves overhead Wednesday morning. Areas of snow and blowing snow will also develop along portions of the North Slope Wednesday into Thursday as the surface low tracks across the area. By Thursday night, temperatures will rapidly cool across Northern Alaska as this system weakens and slides farther east.

KEY WEATHER MESSAGES

Central and Eastern Interior... - Cold temperatures continue through Monday night with valley lows ranging between -20 and -45. Temperatures briefly warm Tuesday through Thursday with highs reaching above 0 in the Central Interior before cooling back to lows in the -30s to -50s late next week. Easterly winds will likely keep wind chill values below -50 for typical valley locations through Monday evening even as temperatures begin to warm.

- Snow expected Tuesday through Thursday throughout the Fairbanks North Star Borough, Central Interior, and Western Alaska Range. Snow accumulations of 6 to 12 inches possible with the heaviest snow currently expected to begin early Wednesday morning. A winter storm warning is now in place with Blizzard Warning for locations at higher elevation.

- Locations above 2000 feet will see wind gusts up to 35 mph. This could create areas of blowing snow reducing visibilities below 1/2 mile at times. Valley locations will see light winds below 15 mph, but paired with heavy snowfall and visibilities could drop to 1/2 mile or less.

West Coast and Western Interior...

- Two waves of snow wash over the West Coast and Western Interior late through Wednesday. Additional snow accumulations of 6 to 12 inches possible in the Northwest Arctic Borough and between 5 and 10 inches expected along the Southern Seward Peninsula and Eastern Norton Sound. Winter Storm Warnings have been issued.

- After this series of storms colder temperatures will return to the region Thursday. Nighttime lows along the coast will be in the 10s to 20s below 0, and the Western Interior seeing 30s and 40s below zero return.

- Another round of northerly winds through the Bering Strait Thursday night is expected. This could create areas of reduced visibility due to blowing snow. These winds will weaken by Friday afternoon.

North Slope and Brooks Range...

- Another storm system will bring additional widespread snowfall and gusty winds to the Western Arctic Coast and Western Brooks Range through Wednesday. - The heaviest snow is expected along the southwestern slopes of the Western Brooks Range with 4 to 8 inches possible. - Gusty winds could lead to periods of reduced visibility due to blowing snow. - Atigun Pass to Deadhorse and Prudhoe Bay will see 1 to 3 inches on Wednesday with southerly winds up to 30 mph Wednesday morning. This could lead to a period of reduced visibility through the pass. A Winter Weather Advisory is in effect late Tuesday night through early Thursday morning.

- Blizzard conditions are possible Wednesday and Thursday around Barter Island. A Winter Storm Watch is out for this area.

FORECAST ANALYSIS AND DISCUSSION

A 1040 mb high pressure remains over the Yukon Territories in Canada this afternoon. This high, combined with 850 mb temperatures ranging from -22 to -30 degrees from west to east across the interior and clear skies, is keeping surface temperatures very cold, on the order of -25 to 45 degrees, with the coldest temperatures in the Upper Tanana Valley and Yukon Flats. A 1002 mb low has moved onshore over the Seward Peninsula this morning. A front extending from it continues to sweep across the Y-K Delta and over the Kuskokwim Valley.

The heavy snow and blowing snow impacting locations along Norton Sound and the western coast this morning is quickly winding down in the wake of both features. Farther north and closer to the center of the low, gusty southeast winds persist across Kotzebue Sound. These winds, however, will be diminishing through the afternoon and evening hours as the low continues to weaken and move east.

Behind both the low and front, a shortwave trough will move east across Eastern Siberia and into the Chuckchi Sea Tuesday morning. An area of frontogenesis is expected in the Northwest Interior with the decaying warm front and the approaching trough. As this trough moves eastward it will continue to flatten and push the ridge axis to the east. By Wednesday morning the reinvigorated warm front will move southeast towards the Tanana Valley.

In the Tanana Valley snowfall is expected to begin Tuesday night, but will remain light until the warm front moves overtop the area. Beginning Wednesday morning heavy snowfall is expected for a 6 to 12 hour period. Here in the Tanana Valley, including Fairbanks, 6 to 10 inches of snow is expected, with most of the steadier snow falling Wednesday morning to Wednesday afternoon. Light snow will continue through Thursday morning. The highest accumulations will likely be along the northern faces of the Western and Central Alaska Range including the Parks highway at Denali Park. We are anticipating 7 to 14 inches of snowfall with the heaviest snow starting midday Wednesday. A strong low-level jet will also likely bring gusty winds to higher elevations above 2,000 feet leading to blowing snow to communities and roadways outside valley locations.

One forecast challenge remaining centers on snow ratios. There is still some model disagreement on what they will be. Sounding profiles for Fairbanks is showing a 400 mb fully saturated Dendritic Growth Zone. Paired with the frontal lift, there is support for ratios higher than 20 to 1. Winds in the Dendritic Growth Zone could limit the snowflake formation, which is the main discrepancy between the models. Some models are showing an 18 to 1 ratio while some get as high as 25 to 1. These ratios would place the snowfall into the forecast range. Regardless of what the ratios turn out to be, the snow will be dry and fluffy.

The front stalls and weakens through Thursday, allowing snow to taper off from west to east. Farther north, the surface low tracks along the arctic coast, with snow and gusty winds likely. The strongest winds look to be from Nuiqsut and Deadhorse east to Barter Island. The combination of snow and wind will likely result in blowing snow and reduced visibilities from Atigun Pass north to Prudhoe Bay. Blizzard conditions may even be possible for Barter Island for Wednesday as a 40+ knot low-level jet may mix down to the surface, resulting in strong wind gusts.

EXTENDED FORECAST DAYS 4-7

As the storm system winds down Thursday, a potent upper-level wave looks to dive southeast from the Chukchi Sea and develop into a strong upper-level trough over the northern Gulf of Alaska by Saturday. This will help to reestablish the large blocking ridge over the Bering Sea, leading to the development of a strong surface ridge over the Eastern Interior and Yukon Territories. The result, is the quick return of arctic air over the Eastern and Central Interior for the end of the week and into the weekend.

There is some uncertainty as to the magnitude of the arctic air, especially over the Eastern Interior. This is due to the development of a surface low somewhere in the northeastern Gulf of Alaska. Southerly flow ahead of this feature, combined with the potential, for a weak upper-leve wave moving northward from the Alaksa Peninsula, may bring some cloud cover to the Eastern Interior.

By Sunday night, another trough will make its way towards the West Coast. This trough will be accompanied with an arctic front, bringing snow and gusty winds. This front looks to not be as impactful as the current systems, but we will continue to monitor as we move forward.

Coastal Hazard Potential Days 3 and 4...None

AFG WATCHES/WARNINGS/ADVISORIES

AK...Winter Storm Warning for AKZ801-807. Winter Storm Warning for AKZ813>824. Winter Weather Advisory for AKZ804-808-809. Winter Storm Warning for AKZ832-839>847. Blizzard Warning for AKZ834-838. Cold Weather Advisory for AKZ835-836. Winter Storm Watch for AKZ805. PK...Brisk Wind Advisory for PKZ801. Brisk Wind Advisory for PKZ802>805-808-811-850-852-853-857. Gale Warning for PKZ806-854. Gale Warning for PKZ807-810-856. Gale Warning for PKZ809-855. Small Craft Advisory for PKZ816-851. Gale Warning for PKZ817. Heavy Freezing Spray Warning for PKZ854.