A mass of Arctic air is expected to make the temperatures plummet in Interior and Western Alaska this weekend, and the cold may also extend to the Southcentral region, depending on how conditions develop.
A map posted by the National Weather Service on social media Tuesday offered a color-coded look at projected lows across the state for next Monday, including temperatures colder than 30 degrees below zero for much of the Interior and in the negative teens for parts of Southcentral.
A special weather statement for the eastern Interior issued Tuesday afternoon by the weather service's Fairbanks office called for a "significant cold spell," including low temperatures near 30 below Friday and 20 below over the weekend before an even deeper plunge going into next week.
"Colder air from the Arctic and Canada will surge south and settle over the Interior early next week," meteorologists wrote. "Temperatures will fall to 40 to 50 below with the coldest area being in the upper Yukon Flats. The Middle Tanana Valley, including Fairbanks, will likely see lows around 40 below by Monday morning."
The conditions are expected to produce a strong temperature inversion, in which cold air is trapped near the ground by a layer of warmer air above it.
Dan Hancock, a general forecaster at the weather service's Fairbanks office, said the cold air mass was moving into the Interior from the northwest — but the situation was "a little bit in flux" due to what it might do over the weekend.
Although inversions typically mean higher elevations are warmer, Hancock said hills across the Interior will still likely be "nasty cold" due to the depth of the air mass.
The mass is also expected to chill the western Interior, which Hancock said might even get the worst of the deep freeze. No weather statement had been issued for the area Wednesday afternoon, although Hancock said that might change as the front arrives.
"Temperatures here will be substantially colder than they have been recently getting," Hancock said. "In places in the western Interior — Galena, McGrath — (expect) temperatures that are substantially colder than they would be in the Fairbanks Interior area."
In Anchorage, weather service meteorologist Dave Kochevar said forecasters weren't yet sure Wednesday whether the cold snap would extend into Southcentral Alaska, despite the chilly temps in the graphic released Tuesday.
"Southcentral is going to be on the very edge of the warm air," Kochevar said. "There's a lot of question whether we're going to be on the cold side or the warm side."
Much of Southwest Alaska will get a blast of cold Sunday and Monday night from the front as it passes through the Interior, however.
"The areas that are really, especially susceptible to the cold — the Kuskokwim Valley, the Aniak-Sleetmute area — will be getting into the (negative) 30s, especially at night," Kochevar said. "We're not looking at record cold, but certainly one of the colder spells they've had going into this season."
Any of the cold air that reaches Southcentral would be unlikely to produce inversions like those in the Interior, according to Kochevar.
Fairbanks forecasters expect the pattern to change following the weekend, but low temperatures are likely to stay for a few days longer.
"It's looking like Sunday night and Monday, this stuff might be moving out," Hancock said. "Perhaps the coldest air might be visiting the Fairbanks area briefly, and then things moderate for a few days — but it still remains quite cold over the western Interior."
Kochevar encouraged people to visit the Anchorage weather service office's website as the weekend approaches for more word on whether the cold snap will reach Southcentral.