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Will This Be a Year Without Winter?

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Will This Be a Year Without Winter?

Generally in January, the reality of winter is beginning to set in. Some eye their wood piles with a jaundiced eye, wondering if that great pile of stored heat that looked sufficient in September is going to get them through March. Others rejoice in winter sports—skiing (both down and cross), skating, snowshoeing and, in this area, even ice bicycling. Sportsmen are digging holes in the ice hoping to pull tasty fish from the depths, while some are already begrudging the constant moving of snow from steps, walks and driveways that strains backs and taxes the heart.

But not this year. Many valley areas are practically bare of snow, and afternoon temperatures not only make a jacket superfluous, some also manage to do without pants. (Shorts. They wear shorts.) So what happened to the winter that most weather professionals predicted would be “snowier than normal?”

Right now, our winter is hanging out up north and current projections are that it might show up sometime between mid-January and mid-February.

Weather, however, is a tricky thing. Events too small to measure have an impact on the weather for any given day, which is why weather predictions are generally iffy any more than three days into the future. If you were to make a chart of the historical range of temperatures and weather events for a given time period, in fact, some studies have shown that throwing a dart and making a weather prediction based on where it lands might even be more accurate than what you hear about next week’s weather on the nightly news.

So how is it we end up with predictions about the weather to come not just weeks, but months into the future?

When it comes to forecasting beyond a few days, we start moving away from weather and moving toward climate: the composite of what’s normal for a given time period in a given region. Climate is generally determined by certain events that are understood well or less well, as the case may be. One such ‘climate event’ that was a big part of the earliest forecasts for this winter’s weather as colder and snowier than normal: a developing La Nina, the same type of weather pattern that buried us hip deep in snow last winter.

La Nina (the little girl) is a weather pattern that develops when temperatures in the Pacific Ocean are cooler than average which, in our area of the world, generally means we’re in for a winter that’s colder and wetter than normal. The heavy snowstorms we were smacked with this November for a couple days were the harbingers of a typical La Nina winter.

So what happened after that? 

First, not all La Ninas are created equal. Last year’s La Nina developed due to a broad band of colder than average water in the Pacific. This year, that band of cold water is much smaller and its temperatures are less extreme; the La Nina it has created, therefore, is much weaker. This year’s La Nina is currently running only about three-quarters of the strength of last year’s La Nina.

Still, if there’s any La Nina at all, winter should be colder and snowier than normal, and that’s obviously not happening (yet). So what else is going on?

Enter the Arctic Oscillation and the North Atlantic Oscillation, considered by many to be relatively the same thing and therefore abbreviated (N)AO for ease. 

Opposing atmospheric pressure patterns in the higher latitudes, the (N)AO can be in either a positive phase, with high pressure over the polar regions and low pressure at the mid latitudes, or in a negative phase, where that pattern is reversed. In its positive phase, which is where it’s at right now, we generally see drier conditions in the United States, while it also puts a brake on the southward passage of frigid arctic air.

The (N)AO can change from one state to the other in the space of weeks, however, so there’s no telling what it will be doing in, say, February, though right now there’s no sign of it changing anytime soon.

Then there’s the jet stream: high level, fast moving air currents that run from west to east. The polar jet stream can send weather almost in a straight line from the Pacific, through Washington, and into our Rocky Mountain homeland on a direct trajectory.

In a La Nina year, however, the polar jet stream gets kicked up into Alaska where it dives south at a sharp angle, almost on a direct run to the northern Idaho panhandle. Cold weather, it should be noted, rides, somewhat, on the northern side of the jet stream.

Right now, though, that jet stream is diving down from Alaska at a gentler angle, skimming the Canadian border and leaving much of our section of the U.S. on the balmy side.

In part, our weak La Nina—which Accuweather senior meteorologist Henry Margusity says could be weakening all the way to the point of becoming a neutral ENSO (the midway state between La Nina and El Nino)—is allowing for a far less precipitous southward movement, leaving a much broader band of mild weather on the southern side of the jet stream.

Another event which may or may not have an effect on weather in our own region is the development of a Greenland Block, which is, so far, missing in action this year. 

The Greenland Block is the development of a high pressure system over—you guessed it—Greenland, that exerts pressure from the east on Canada’s arctic air, which is attempting to move east itself; this forces cold air to move south and was the mechanism responsible for much of last winter’s frigid cold. Weather experts say low pressure systems moving east have so far prevented a Greenland Block from setting up but that, too, can change.

There are other things that effect the weather as well in a milder way: the Madden Julian Oscillation, (active and “contributing variability”) and the Pacific Decadal Oscillation. The observations of all these actions are combined with statistical forecast tools like canonical correlation analysis, screening multiple linear regression, constructed analog and ensemble CCA to develop the forecast, which the National Weather Service updates in the middle of every month. And that sentence should explain why whether is so difficult to understand.

For our area, we should know that frigid air is still piling up in the arctic, and the NWS weather experts are still holding firm to their projections for a winter season colder and snowier than normal.

That prediction, based on the continued La Nina, does buck odds based on trends, however, because 66 percent of the time, when winter starts out as relatively dry as it has, it remains that way through the spring. 

Snow or no snow, even those who are rejoicing in our mild winter weather, however, are eyeing the snow in the mountains, wondering whether it’s enough to refresh aquifers, fill streams and dampen next summer’s fire season. And Idaho snotel data for the panhandle shows reason for some concern: basin-wide, snowpack is only 93 percent of normal. (Schweitzer Mountain, by the way, is at 112 percent of normal.)

Regardless of how the rest of the season turns out, the first portion of it has been undeniably mild. And while I might not know ‘weather,’ I do know that mild winters in North Idaho (even if only a portion are mild) are generally followed by one heck of a mosquito hatch. So while neither I (nor the National Weather Service) can tell you definitively whether or not you can put the snowblower away for the season, I can recommend that you stock up on the bug spray.

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Author info

Landon Otis

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Homepage, Headlines, mosquitos, winter, Trish Gannon, weather, La Nina, snow, snowpack, Snotel, winter 2011-2012, Arctic Oscillation, North Atlantic Oscillation, jet stream, Greenland Block, Henry Margusity, ENSO, Madden Julian Oscillation, Pacific Decadal Oscillation, National Weather Service

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