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Coldest air of the winter on the way next week?

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With the warm air moving in this week many have given up on any winter weather again this year. I think mother nature is saying to us, “Not so Fast!” There are very good signs that something called a “Sudden Stratospheric Warming Event” may mean major cold for the US by the end of this month.

Now this sounds like something out of the movies but it’s one of the most dramatic events that occurs in the stratosphere. Typically an area we think of where the Ozone layer is. What essentially happens is a rapid warming of the stratosphere(6-30 miles up) occurs. This is above where weather occurs in the troposphere. Now when I say warming it’s not like above freezing but warming from lets say -75°C to maybe -25°C.  This rapid warming disrupts the position of Polar Vortex and shifts major Arctic surface air south into the lower latitudes. The Polar Vortex is just the position of the coldest air over the poles. This warming is already underway and has shifted the cold air/Polar Vortex into Siberia first.

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These warming events in the stratosphere have been documented for some time. They have been responsible when combined with other global climate oscillations to create major cold air outbreaks in lower latitudes. The easy part is the recognition that they are occurring. The hard part is forecasting where the cold air will go and for how long. Sometimes the polar vortex will break into two parts or just be offset further south. Then like water falling on the top of a ball you don’t always know which way the water will flow off the ball. Since the Earth is just a big ball the cold air is hard to predict where it will fall south from these events.

Currently the bulk of the cold air is in Russia but some is still in place over Canada. Siberia and Northern China are having the coldest winter in decades.

Top of the World:

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North America:

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Asia & Siberia:

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Past Events:

It’s always hard to repeat the exact pattern but there have been crazy reversals of mild weather to the deep freeze due to these events. One such event is the Arctic Outbreak of 1985. That late January 1985 All-time state records were set in North Carolina -34°, South Carolina -19° and Virginia -30°. In Charlotte on January 21st, 1985 we had a high temperature of 24° and an all-time record low of -5°. What’s so crazy about this outbreak is that the preceding December was extremely warm in the same areas that got blasted in late January.

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Then this happened late in January:

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The cause was a Sudden Stratospheric Warming event not too different from the current one that just started. In 1985 the SSW event occurred on Jan 3rd but the cold didn’t arrive in the U.S. until 2 weeks later.

(Courtesy Patrick Martineau)

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Forecast:

Like I mentioned before I know someone is going to get the deep freeze the question is exactly where. I don’t think we will see anything like 1985 but even a glancing blow could really be a shock to our system after the mild start to winter. The long-range models are starting to come around to this developing event. The modeling and guidance we use usually has a tough time accounting for such events until they start to unfold. The ECMWF and the GFS models are both picking up on the cold returning. Here’s a look at the progression of the cold air from the GFS model. The following maps are the temperature anomalies which is the departure from normal temperatures. This is always a better gauge of the pattern than any specific temperatures.  I would still caution though this is just a model and not a forecast.

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Conclusion:

There are many variable to look at among the SSW event but based on this the shifting of other indices like the Arctic Oscillation, North Atlantic Oscillation, PNA & MJO. Signs point to a big cool down for the end of the January into February. It maybe one good blast then done or it could establish a very cold end to the winter. Time will tell for sure but after near 70° this weekend it going to be a major cool down by the end of next week. Stay tuned!