The upper part of the climate atmosphere is undergoing major changes now. The researchers found that these changes occurring high in the air eventually transfer to a realignment of the weather pattern here on the ground.
The second part of the Earth’s atmosphere is called the stratosphere. It is at the top of the troposphere, where it occurs most of the time. Currently, a Sudden Stratospheric Warming (SSW) is underway.
The stratosphere is about 30,000 meters above the ground. Typically, in winter, there is a rotating vortex centered on the north pole, with the vortex in the stratosphere. This is the vortex that most researchers call the Polar Vortex. On December 25, the average temperature in this vortex started to warm up. Since then, the temperature around 100,000 feet has risen 54 degrees Fahrenheit. While this may be what you think defines an SSW, there is actually another feature of the climate that researchers should use.
Michael Ventrice, Ph.D, and an IBM meteorologist, says the real key indicator is when the winds from the stratospheric vortex slow down and reverse direction. Ventrice originally studied tropical meteorology and how atmospheric waves in other parts of the globe affect hurricanes in the Atlantic. Ventrice was doing a graduate degree in meteorology in 2012 and says the sudden stratospheric warming was being discovered. He believes that understanding the stratospheric polar vortex and sudden stratospheric warming will be the key to issuing a more accurate sub-seasonal forecast. A sub-seasonal forecast would be a 30-day to 45-day forecast.
Flow deviation and average temperature around 100,000 feet. Large red and white area means the stratospheric heating area
Ventrice explains how the domino effect occurs during and after an SSW. The spiral vortex decreases and the normally west wind, turning high above the north pole, becomes an east wind. The vortex, called the Polar Vortex, then slides and is centered over the north pole. At this point, Ventrice says where the vortex changes is the key to the weather in the eastern United States in the coming weeks. This SSW has the polar vortex initially changing to be centered in Siberia.
Temperature anomaly forecast at 100,000 feet by January 15, 2021
Now let’s start talking about the climate that accompanies it in the atmosphere, in the troposphere and here on the ground. As the stratospheric vortex moves into Siberia, a strong and deep storm system develops over the North Pacific. Strong storm systems dominate and double the jet stream in North America. The jet stream comes from the Pacific storm and crosses Canada, bottling the cold air from northern Canada. Therefore, Ventrice says that the first effect of this particular SSW is a period of heat throughout the eastern United States. This is the period of heat that we are currently in Michigan and the Great Lakes. It is not extremely hot, but we are five to 15 degrees hotter than normal. After about a week, the strong storm in the North Pacific is replaced by a strong high pressure ridge. Cold air begins to form in western Canada. The domino effect then curves the jet stream south through the eastern US. Ventrice says that about two weeks after this SSW, the cooler air is expected to move to the eastern US
The weather direction flow forecast (about 15,000 feet upwards) for January 11 to January 15 shows a colder flow developing in the eastern United States (graph courtesy of Judah Cohen-AER, A Verisk Company)
All the weather models that we, meteorologists, including Ventrice, observed show a slightly cooler pattern in mid-January.
Surface temperature anomaly forecast for January 11 to January 15. (Image courtesy of Judah Cohen- AER, A Verisk Company)
But will the cold be strong and last for a long time? Ventrice’s research shows that when a sudden stratospheric warming begins to move to Siberia, the after effects on Michigan and the eastern US are transient. He thinks the cold usually lasts for a week or more, and then can return to a warmer than normal pattern. Ventrice says that this pattern of coming and going from cold to hot can go through two or three cycles. This would give Michigan and the eastern United States a pattern of high and low temperatures until mid-February.
Ventrice found a more severe and lasting cold pattern when the SSW starts over the North Atlantic.
One more thing Ventrice observes to predict the severity and duration of the cold in the eastern United States – an air blockade over Greenland. A strong upper-level block over Greenland increases the southward twist in the jet stream over the eastern United States. Currently, a Greenland bloc is expected, but not to a very strong extent.
What does all this mean for Michigan?
The main point here is that the upper atmosphere is undergoing some significant changes now and in the coming weeks. This should bring Michigan and the eastern United States to our first real cold winter blast. Does this bring snowstorms? It is difficult to say yet, but the cold is necessary for snowstorms. Therefore, the first piece of a winter puzzle is likely to be ready by January 15-18.
Ventrice suggests that the next research path will be to learn how to quantify the amount of cold and the duration of cold after these sudden stratospheric warming. Ventrice reminds us that this is a relatively new forecasting technique for long-term forecasting.