SARANAC LAKE — With bitter cold, gusty winds, low gray clouds and fine snow flurries omnipresent this week until today, people across the Tri-Lakes region would be forgiven for thinking that they have found themselves in the 1993 “Groundhog Day” movie over the past few days.

The film stars Bill Murray as — of all things — a weatherman who wakes up each morning to find that it is a carbon copy of the previous day.

In reality, the notable consistency of weather conditions from Sunday through Thursday this week can be attributed to what meteorologists term an “upper-level low,” according to Scott McKim, the science manager at the Atmospheric Sciences Research Center’s Whiteface Mountain Field Station.

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The science behind the storm

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McKim said the science is complicated, but in its most basic terms, an upper-level low refers to a colder pool of air in the atmosphere.

Rather than moving through the region in one direction, the low pressure has slowed down and has instead stalled for much of the week and — like a tire without traction — has been spinning over the area in a more-or-less stationary counterclockwise pattern without moving forward. This has led to very similar weather conditions each day.

McKim said the storm system was trapped in place over the area as a result of the jet stream’s behavior. Even though the jet stream is still in motion, its directionality enabled the low pressure system to become stuck-in-the-rut, and spin in place.

The jet stream is a rapidly-moving column of air that generally moves from west to east, high in the atmosphere. In addition to serving as a path for storms to track along, in the Northern Hemisphere it tends to separate cold air to its north and warm air to its south.

Ridges and troughs are common jet stream features. Ridges refer to the jet stream arching northward, bringing warm air from the Equator closer to the North Pole. Conversely, troughs bend the stream south, bringing cold air from the North Pole closer to the Equator.

“The long wave pattern has kind of been stacked, with an upper-level ridge which has been very durable over Greenland, magnified by the ridge over the west,” he said. “It has induced this trough in between (over eastern North America) and that trough is having trouble moving out because the ridge downstream is so durable.”

McKim said it was part of the same big-picture global weather pattern that has led to ravaging wildfires in California, fueled by dry weather and strong winds there.

“It’s that same ridge out west that is contributing to the Santa Ana winds and the fires by LA, so it’s all connected, as they say,” he said. “They’re under terrible conditions but it’s kind of that big synoptic setup that’s resulting in this lobe of very cold air being circulable in the East here.”

McKim said that trapped within these rotations are areas of snow, which have been impacting a large area — much of eastern Canada, northern New York and New England — although accumulations have generally been light.

“Embedded in there are just these little short waves and vortices of pockets of increased moisture and lift,” he said.

When moisture lifts in the atmosphere as water vapor, it cools and condenses from an invisible gas to a visible liquid or deposes from a gas to solid, skipping over the liquid phase.

McKim said that precipitation this week was consistently light and fine because of the extreme cold, which makes it tougher for the atmosphere to hold — and ultimately deposit back to the ground — large amounts of moisture, in this case, as snowfall.

“It’s pretty moisture-starved right now,” he said. “You generally want (atmospheric moisture) saturation in the dendritic growth zone — kind of where that optimal place for snowflakes to form — and with these cold temperatures, it’s just so moisture starved.”

McKim noted that specific temperatures — beyond being merely below freezing — play a huge role in snow formation, with extremely cold temperatures being a hindrance, but not a fatal condition, to snow formation.

“I mean people throw around the phrase ‘It can be too cold to snow,’ and I don’t know if that’s actually ever the case, but it does get very hard when there’s air that’s so cold it just can’t hold that much moisture.”

One characteristic, McKim said, is the formation of fine snowflakes that are light in weight that can, when combined with even a gentle breeze, reduce visibilities, as they are more easily manipulated by the wind.

“There’s not much accumulating but there’s enough to perhaps be a nuisance to drivers and shovelers,” he said.

Coupled with that, salt that road crews use to keep snow and ice from building up on roads loses its potency with the frigid cold, especially around popular commute times, when the sun angle is not as strong — even through the cloud cover — to aid in the melting process on darker surfaces, such as roads.

All this is to say, roads may be slicker and snowier, even as the overall accumulations are low, requiring more time to be built into commutes, even as the weather forecast may not appear to be that impactful at first glance.

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A unique twist

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McKim said one distinction that made this week’s upper-level low somewhat unique was its location.

“This latest low — I’d say over the last four or five days — has been kind of unique in that there’s this upper-level low but it has these energy pockets wrapped around it that are situated over eastern Quebec, almost the Canadian Maritimes,” he said. “So, we’re getting (wind) flow from the northeast into us.”

McKim said he noticed the change in direction first-hand as part of his commute. His job requires frequent trips up to Whiteface Mountain’s summit to oversee various meteorological and climatological observation equipment that the Atmospheric Sciences Research Center maintains there, commutes he often makes on skis.

“Anecdotally, when I skied up to Whiteface (Wednesday) on the toll road, I do it so often that I start to recognize nuances like where are drifts forming,” McKim said. “The road was like I’ve never recognized it before. There were drifts in places where I’ve never seen drifts. It was scoured in places where there are typically drifts and it all speaks to — I don’t want to say the rarity — but it’s not typical to have north or even a small easterly component of wind here. It’s traditionally west or northwest in the winter.”

He said this led to northeasterly-facing mountain slopes receiving more snow than the usual western-facing sides bearing the brunt of the snow. He said, as is often the case, higher elevations received more snow this week than lower elevations, something for people who plan on hiking or otherwise recreating in the backcountry to be aware of.

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Brief warm-up

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Meteorologists said they expect a departure from these bitter cold conditions today and over the weekend, as a change in the jet stream finally pushes the spinning upper-level low out of the region.

“It’s been something like rereading the same pages of a book in recent days for our weather,” the National Weather Service’s Burlington, Vermont office, which serves the Tri-Lakes region, noted in its forecast overview Thursday around press time. “But the pages will turn later (Thursday) as snow showers gradually come to an end. Winds will also relax.”

McKim noted that the change in pattern, however, would not last long — or get all that warm — before reverting to similar conditions next week to what the local area saw throughout much of this week.

“A little upper-level ridge builds in for this weekend, which by standards feels warm, but is still just in the 20s for highs,” he said. “Then, kind of the same thing over again next week. A deep, deep pocket of cold air kind of comes down from Canada and gets situated over the Upper Great Lakes and Minnesota area Monday, and then kind of Tuesday-Wednesday moves into our area.”

While temperatures may not get as cold as earlier this week, McKim said the forecast after this weekend’s brief reprieve was similar to what was seen for much of this week.

“It’s just kind of a persistence forecast. Just windy, blustery west, northwest winds with the pressure gradient, and then just kind of flurries,” he said.

To put it less scientifically, it may be Groundhog Day all over again for the Tri-Lakes.