After another couple days of balmy weather, local meteorologists are confident that at least the first two weeks of January will feature seasonable and/or below-average temperatures for the Tri-Lakes region.

While emphasizing that it is too early to pinpoint exact temperature forecasts beyond a week, meteorologist with the National Weather Service’s Burlington, Vermont office, which serves the Tri-Lakes region, are seeing broad large-scale shifts in the atmospheric and oceanic patterns that point to colder weather in store by the end of the week.

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Immediate concerns

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With above-freezing temperatures through mid-week and rain expected today and Wednesday, meteorologists are keeping an eye on the water. Tyler Danzig, a meteorologist with the National Weather Service’s Burlington, Vermont office, said fortunately all of the data he saw indicates minimal impacts.

Danzig added that the storms today and Wednesday are both expected to drop relatively small amounts of precipitation — each less than half an inch — and the gradual nature of the warm-up will help to prevent ice jams, which occur when a large volume of thick ice moves down the river at once and then gets stuck at a narrow point, backing up the river and resulting in flooding.

“We’re not expecting any ice jams,” he said. “Temperatures are going to be above freezing for quite a while, so things are going to thaw out. We don’t have any real thick ice out there either right now. In terms of river flooding, we’re not expecting anything right now along the AuSable. Water will definitely rise, but we’re not expecting it to reach action stage or anything higher than that as of right now.”

Danzig said temperatures begin cooling back to normal on Wednesday, resulting in that day’s storm possibly ending as snow for the Tri-Lakes, but again cited its overall low precipitation totals resulting in minimal weather-related travel impacts.

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Back into the freezer

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Even though December had plenty of snow and cold, those periods were frequently punctured by thaws. Danzig said the upcoming weather pattern is expected to result in more durable and consistent cold weather.

“We’re getting out of this ‘blocking pattern,’ which is causing the warming,” he said. “There’s a high (pressure system) that’s situated out on the Atlantic that’s causing these lows to track a little bit further west of the area and then ride north into Canada and then out to sea.”

The high-pressure system responsible in part for this warm-up is centered near Bermuda, placing much of the Northeast in the system’s warm air zone and leading to storm systems that produce rain, rather than snow.

High-pressure systems — in addition to tending to bring calm weather to areas situated underneath them — spin in a clockwise direction in the Northern Hemisphere. This tends to bring cold air from the north to areas east of the high pressure’s center, and warm air from the south to areas to its west.

As the ‘Bermuda high’ weakens and is dislodged throughout the week, Danzig said the jet stream should set up in a way that favors more snow storms. He said computer models were showing “teleconnections” — which refer to large-scale oceanic and atmospheric patterns that dictate the movement of warm and cold air masses around the globe — favorable for cold and snowy weather over the eastern U.S. for the next couple of weeks.

Danzig referred specifically to the North Atlantic Oscillation and Pacific/North American pattern, which he said function together to lift the jetstream up north over the western U.S., resulting in warmer weather there and then drive it down south over the eastern U.S., resulting in cooler weather there.

He said the bends in the jet stream — where it changes direction from north to south or vice versa — are sources of fuel for storm systems, which tend to become stronger as they rotate and make their way around these bends.

“Most of that means we’re looking at lows that are going to have higher cyclogenesis,” he said. “Which is going to not only mean potentially more of them as we move forward, but also they’ll be able to draw in more of that cooler air out of the Arctic and Canada (resulting in precipitation falling as snow as opposed to rain).”

Danzig emphasized that these forecasts were general trends, and not meant to provide specific guidance, such as precisely how cold it may get on a certain day or when exactly a snowstorm is likely to hit the Northeast. He said that rather, meteorologists look at the upcoming teleconnection patterns and look back at recorded periods of past weather to try to get a general idea of how conditions for an area will play out based in part on how they did in the past.

“They look at those indices to determine climatology for a couple weeks or a couple months out,” he said. “Then, they look at analogs. What does the current pattern look like in terms of past events? If we have something that’s going on right now, and then we look at analogs, what are those analogs doing based on what we have right now? We’re kind of comparing the patterns, that sort of thing.”

Danzig added that this comparison gets trickier the further into the future meteorologists try to look.

“To a decent accuracy, those trends are accurate up to two weeks,” he said. “Then once you get out further, the scale definitely decreases pretty quickly.”

While a January thaw may come to fruition later in the month, winter weather enthusiasts likely have at least the first half of the month to make the most of.