textproduct: Fairbanks

SYNOPSIS

A very cold airmass will continue to build into Northern Alaska out of the northeast early this week, plummeting temperatures well below normal as winds ramp up and remain elevated along the Arctic/West Coasts and across higher elevations. Widespread double digit below zero temperatures reaching down to -20F to -50F are expected to fill in regionwide through Tuesday, with even colder wind chills at times. Snow chances through Monday will remain confined to the Southeast Interior and North Slope/Brooks Range, ahead of a more organized push of moisture Tuesday into Wednesday expanding those chances areawide out of the southeast. While snowfall accumulations through Wednesday are expected to remain light overall, a Winter Storm Watch has been issued for the Richardson Highway over Isabel Pass where 6-12" of snow is possible. A mix of Blizzard Warnings, High Wind Warnings, and High Wind Watches are now in effect for portions of the Arctic/West Coasts to capture where the strongest winds and more significant blowing snow is expected. Increasing southeasterly flow midweek will lead to warming temperatures, with isolated snow chances sticking around through next weekend.

KEY WEATHER MESSAGES

Central and Eastern Interior...

- Light snow will continue for the Upper Tanana Valley through Monday, as cold and dry conditions prevail across the rest of the Interior with a mix of sunshine and low clouds.

- Temperatures will trend colder through Tuesday as strong inversions persist, with coldest valley locations reaching down to -30F to -45F with even colder wind chills.

- Widespread light snow will build into the Interior out of the southeast Tuesday into Wednesday, with moderate to heavy snow possible for the Southeast Interior and Eastern Alaska Range.

- Winds will ramp up across higher elevations Sunday into Monday, peaking on Tuesday and Wednesday as gusty winds expand to the Middle Tanana Valley around Delta and through Alaska Range Passes.

- Warmer temperatures will also build in midweek, returning to more seasonal levels to finish out the week as drier conditions prevail Thursday onward.

West Coast and Western Interior...

- Winds have already begun to ramp up across Western Alaska, with wind gusts of 30-60 mph becoming widespread along the West Coast and at St. Lawrence Island early this week. Winds will remain elevated through midweek with areas of blowing snow at times.

- Strong northeast will usher in a colder airmass to the region early this week, with coldest locations reaching down to -15F to -40F through midweek with even colder wind chills.

- High Wind Warnings remain in effect through Wednesday for St. Lawrence Island and Bering Straight Coast where a prolonged high wind event is expected with gusts as high as 60 mph.

- Conditions will remain dry across Western Alaska through most of the day on Tuesday, with isolated rain/snow showers possible for the southern Y-K Delta today.

- More widespread light snow chances will build in regionwide southeast to northwest late Tuesday into Wednesday, shifting to the West Coast for Thursday, as warner temperatures also work back in mid to late week.

North Slope and Brooks Range...

- Light snow and wind gusts of 30-40 mph will continue across the Eastern North Slope/Brooks Range today into tonight. Wind gusts up to 60 mph are expected tonight into Monday for the Eastern Beaufort Sea Coast where a Blizzard Warning is now in effect.

- Significantly colder temperatures have begun building in out of the north, with widespread double digit below zero temperatures expected to fill in regionwide through midweek. Coldest locations are expected to drop to around -30F to -50F.

- Cold Weather Advisories have been issued for portions of the Brooks Range and Dalton Highway for wind chills as cold as -70F. These advisories will likely need to be expanded further across the North Slope to capture the widespread frigid wind chills.

- Winds will remain elevated through midweek with gusts up to around 30-50 mph, peaking for most Tuesday into Wednesday. A High Wind Watch has been issued for the NW Arctic Coast where gusts up to 70 mph remain possible Tuesday through Wednesday night.

- Following a more organized push of snow on Monday for the Eastern North Slope where several inches of snow are expected, snow chances will become more isolated Tuesday ahead of another round of widespread light snow Tuesday night into Wednesday.

FORECAST ANALYSIS AND DISCUSSION

Today through Tuesday Night. Early morning satellite imagery shows a 500 dm upper level low centered over Banks Island in the Canadian Archipelago tracking southwest over the High Arctic towards Northern Alaska. This upper level system will work to bring about a significant pattern change, supporting the return of much colder temperatures, gusty winds, and increasing snow chances. Strong cold air advection out of the northeast will allow for 850 mb temperatures to plummet to around - 20C to -35C, supporting the return of widespread double digit below zero air temperatures regionwide through midweek as coldest locations drop to around -30F to -50F. Wind chills will be even colder at times.

A tightening pressure gradient and stronger winds aloft have already begun to shift into our area, which will lead to increasing surface winds over the coming days particularly along the Arctic/West Coasts and across higher elevations. As the aforementioned upper level low tracks southwest towards the Bering Sea, this will maintain and or strengthen winds through Tuesday as strongest winds ultimately shift north Tuesday night into Wednesday. Winds in stronger corridors along the coasts and higher elevations will see wind gusts around 30- 50 mph, locally stronger up to 60-70 mph especially for the NW Arctic Coast southwest to St. Lawrence Island. A mix of warnings and watches have been issued to capture where strongest winds are expected through midweek. Additional wind and cold weather products will likely be needed in future forecast issuance as confidence increases on exact locations that could see high winds, extreme cold temperatures, or both. Additionally, we will be monitoring the blowing snow potential as well when to weigh a wind or winter product issuance. On Tuesday, we are also looking at the potential for strong gap winds to fill in through the Alaska Range Passes and across the Middle Tanana Valley around Delta Junction with wind gusts in excess of 40-50 mph possible.

Snow chances through Monday will remain confined to the Eastern North Slope/Brooks Range and Southeast Interior, ahead of a regionwide expansion Tuesday into Wednesday. Through Monday, models have trended a bit higher for snow amounts on the North Slope to several inches with amounts favored to remain light further southeast. The track of an upper level low over Northern Alaska towards the Bering Sea will advect moisture from the Gulf of Alaska during this timeframe, tapping into a larger plume of moisture from a series of stronger surface lows. As a result, snow chances will expand regionwide southeast to northwest Tuesday into Wednesday with widespread light snow expected. Increasing confidence supports more moderate to heavy snow potential across the Southeast Interior and Eastern Alaska Range where a mix of Winter Weather Advisories and or Winter Storm Warnings will likely be needed to capture where the heaviest snow amounts are expected. As of our latest forecast, a first look at totals in this corridor show 3-6" in the valleys and 6-12"+ in the mountains. A Winter Storm Watch has subsequently been issued for the Eastern Alaska Range over Isabel Pass for Monday night into Tuesday.

EXTENDED FORECAST DAYS 4-7

Wednesday through next Sunday. Active weather continues into the start of the extended forecast across Northern Alaska as an upper polar low traverses the state and moves off into the Bering Sea Wednesday through the end of next week. As the polar low heads west, the next pattern change begins as southeasterly flow sets up across Eastern Alaska and brings increased moisture and warmer temperatures back northward. The arctic airmass quickly retreats into Siberia with a significant increase in 850 mb and low level temperatures, allowing for temperatures to return to more seasonable levels for mid to late this week. As we progressively lose the pressure gradient and elevated winds aloft, the strongest winds will continue to shift north Wednesday into Thursday, as winds lessen to gusts of 20-30 mph along the coasts and higher elevations through the weekend and up to 40 mph for the NW Arctic Coast.

Snow chances will continue through next weekend as numerous systems in the Gulf of Alaska send waves of energy northwards, with our latest forecast at this time keeping amounts light and supporting a fairly quiet weather pattern returning to our CWA. Temperatures during this timeframe look stabilize or warm as most locations see highs rise back above zero. While high temperatures rise above zero for many locations by the end of the week, larger diurnal ranges and sub zero lows will be common for most as clearer skies at night allow for good radiational cooling.

Coastal Hazard Potential Days 3 and 4...None

AFG WATCHES/WARNINGS/ADVISORIES

AK...Cold Weather Advisory for AKZ809-811. Cold Weather Advisory for AKZ812. High Wind Warning for AKZ820-827. Winter Storm Watch for AKZ805. PK...Brisk Wind Advisory for PKZ801>807-810-811-850-852-853-856-857. Brisk Wind Advisory for PKZ814. Gale Warning for PKZ815-861. Gale Warning for PKZ816-817. Gale Warning for PKZ851-854. Brisk Wind Advisory for PKZ860.