textproduct: Fairbanks

SYNOPSIS

A storm brings heavy precipitation to Southeastern Alaska and the Eastern Alaska Range Sunday and Monday. This precipitation will mostly be snow with some partially melted snow mixed with rain possible below 1500 feet. The North Slope cools rapidly Monday and Tuesday and then remains cold through the end of the week. Areas of fog remain along the West Coast and are expected to slowly improve through Monday. Another low pressure system will bring a front across southwestern Alaska bringing another round of light rain and snow to the West Coast and portions of the Interior Tuesday through the end of the week.

KEY WEATHER MESSAGES

Central and Eastern Interior...

- Heavy precipitation is expected across the Eastern Alaska Range and Upper Tanana Valley Sunday through Monday with lighter accumulations lingering into early Tuesday. Above 1500 feet snow totals may exceed a foot of fluffier snow. Below 1500 feet snowfall totals of 6 to 12 of denser, wetter snow is possible. The heaviest precipitation is expected Sunday evening through early Monday from Tok west to Isabel Pass with lighter accumulations expected from Delta north and east of Tok. Winter Storm Warnings have been issued.

- Snowfall is expected across the Fortymile Country and White Mountains Sunday through Monday. 4 to 6 inches is expected above 1500 feet including the Steese Highway near Eagle Summit. North to northeasterly wind gusts of 20 to 30 mph could lead to areas of blowing snow. Conditions are expected to improve by Tuesday. - Northerly winds gust up to 35 mph through the Alaska Range Passes Monday. Northwesterly wind gusts up to 35 mph are possible through the Upper Tanana Valley. There may be areas of reduced visibility when paired with falling snow. Near whiteout conditions are locally possible where the strongest gusts and heaviest snow overlap.

- Temperatures gradually cool this week with highs in the mid 30s and lows in the upper teens. Any liquid surfaces or melting precipitation may fully or partially freeze overnight, creating slushy or slick spots in the morning.

West Coast and Western Interior...

- Northerly winds gust as high as 40 mph through the Bering Strait Sunday through Monday morning. Blowing snow and fog will reduce visibility to 1/2 mile or less at times. A winter weather advisory has been issued.

- Temperatures cool throughout the week with highs in the 20s and overnight lows in the teens to single digits above zero. Slick and icy surfaces may form where liquid or melting precipitation freezes overnight.

- Another round of precipitation approaches the West Coast Tuesday bringing periods of light rain, snow, and mixed precipitation to portions of the West Coast and Western Interior Tuesday through the end of the week. Precipitation will be most consistent for areas south of the Bering Strait along the West Coast and south of Huslia across the Western Interior.

North Slope and Brooks Range...

- Scattered snow showers linger across the Brooks Range into next week, especially along southern facing slopes. Travel through Anaktuvuk Pass or Atigun Pass may be slightly impacted by light snowfall and breezy northerly winds.

- Temperatures rapidly cool Monday and Tuesday and then remain cool through the end of the week. Highs fall to the single digits above zero while overnight lows reach as cold as the teens below zero. - Periods of gusty winds return to the northwest Arctic Coast Tuesday through the end of the week. Gusts as high as 40 mph between Point Hope and Point Lay.

FORECAST ANALYSIS AND DISCUSSION

For Sunday through Wednesday. At the start of the forecast period Sunday, a 520 decameter upper level low quickly shifts from the eastern Bering Sea to the Gulf of Alaska where it then strengthens slightly. A surface low underneath this upper level low attempts to follow it, but gets shredded apart upon the Western Alaska Range bringing a period of heavy snow to the northern and western portions of that area through Sunday. Two new surface lows form shortly afterwards Sunday afternoon in the Gulf of Alaska and northeast of there on the Canadian side of the border east of the Upper Tanana Valley. These two system then work to pull a large amount of moisture into the Upper Tanana Valley and Eastern Alaska Range Sunday night through Tuesday morning.

There remains a great deal of uncertainty regarding the exact snow amounts with this system due to the chaotic nature of these lows which will affect the timing and exact location of the heaviest bands of precipitation within the storm. Should these heavier bands fall nearer the mountains or overnight much of the precipitation will fall as a fluffier snow above 1500 feet and a denser, wetter snow below 1500 feet. Should these heavier bands fall deeper into the valleys and nearer to peak daytime heating, much of the precipitation will fall as melting snow and rain. Even during these periods that limit snowfall the heaviest bands of moisture within this system are very likely to have high enough snowfall rates to overwhelm surface warmth and eventually turn from mixed precipitation to just snow. Currently the most likely timing of the heaviest precipitation is Sunday evening and overnight with lighter rain/snow lingering through Monday and fading Tuesday. The north facing slopes of the Eastern Alaska Range will see considerable snowfall with the greatest accumulations currently expected from Isabel Pass to the Robertson River. Gusty north/northeast winds along ridgetops and northwest winds through the Upper Tanana Valley may additionally lead to periods of reduced visibility due to blowing and falling snow, although the wetter snow will be significantly less likely to blow.

This system's movement fully pushes the weak ridging out of the region and allows for a weak shortwave low rotating around a much larger upper level low in northern Canada to push towards the North Slope. Temperatures fall rapidly as this shortwave pulls colder air from the north against the Brooks Range Monday into Tuesday. However the weaker nature of this Arctic shortwave will limit much of the wind and snow impacts to the the Brooks Range where there may be some travel impacts near the Atigun and Anaktuvuk passes.

Another low moves into the Bering Sea Monday and a front from it reaches the Lower Yukon Tuesday. There is a much weaker pressure gradient with this low, so winds are expected to be weaker than the previous several systems that have moved through the West Coast. This low will bring another round of light rain, snow, and mixed precipitation to Western Alaska Tuesday through at least Thursday, but will not impact the Eastern Interior nor the North Slope very much due to the presence of the Arctic airmass over the North Slope.

EXTENDED FORECAST DAYS 4-7

For late Wednesday through next Sunday. At the start of the extended forecast period late Wednesday, a low in the Bering Sea continues to extend an occluded front over Alaska bringing light rain, snow, and mixed precipitation to the southern portions of the West Coast and Interior. A low in northern Canada continues to push cold air into the region from the north while lows in the Bering and North Pacific continue to push warmer, wetter, air into the region from the south. A period of relative calm is expected for the early portions of the extended forecast period, but yet another low approaches the Bering Sea Saturday that may impact the region once again. There is currently a great deal of uncertainty regarding how far north a front extending from this low reaches. Building surface pressure in the Arctic may keep much of the moisture south of the Lower Yukon and Alaska Range, but if the low can push through the higher pressure, then additional widespread rainfall may occur early next week.

Coastal Hazard Potential Days 3 and 4...None

AFG WATCHES/WARNINGS/ADVISORIES

AK...Winter Storm Warning for AKZ836-849. Winter Weather Advisory for AKZ837-847. Winter Weather Advisory for AKZ820-821. Winter Weather Advisory for AKZ834. PK...Brisk Wind Advisory for PKZ805-853. Brisk Wind Advisory for PKZ806-854. Brisk Wind Advisory for PKZ807. Brisk Wind Advisory for PKZ807. Brisk Wind Advisory for PKZ808-809. Heavy Freezing Spray Warning for PKZ816. Brisk Wind Advisory for PKZ817. Gale Warning for PKZ856.