Friday, December 13, 2013

Long Range Lookout: Brutally Cold December Continues into January

New data I've compiled over the past few weeks leads me to believe that the end half of December and on into January will be filled with some pretty cold weather.

This data came as a result of analyzing the stratosphere, and determining the placement of temperature anomalies. Using a 2-4 week gap between warming and cooling air masses in the stratosphere, something I like to call the Stratospheric Temperature Index (STI) was created. 

For some verification, take a look at this text from a post I made on December 1st:

Between October 30 and the first few days of November, the Central and East US experienced above normal temperatures in the upper stratosphere. This is displayed well in the Climate Prediction Center's reanalysis of the 30th in the image above. These few days between the end of October and the start of November also included slightly above normal stratospheric temperatures diving south from Canada, with below normal temperatures observed in the Pacific Northwest. Because the effects of stratospheric warmings are typically seen 2-4 weeks after the warming event, we took a look at surface temperatures from November 14-28 to see how well the surface temperatures matched up with the upper stratospheric temperature anomalies (note that this is a negative correlation relationship, meaning above-normal stratospheric temperatures will lead to cold surface temperatures, and vice versa).
Ground-level temperature verification from November 14th to November 28th, approximately 2-4 weeks after the height of this US upper stratospheric warming event, is nearly identical to the temperature anomalies experienced in the stratosphere. The regions that saw above normal stratospheric temperatures, including the Central and East US, as well as Canada, saw below normal temperatures during this timeframe. Similarly, the Pacific Northwest, which was bathed in slightly below normal upper stratospheric temperatures to kick off November, was included in slightly above normal surface temperatures from November 14th to November 28th. It would seem to me that the stratosphere had a direct involvement with these surface temperature anomalies, given how well the stratospheric and surface temperature anomalies line up. (End Dec. 1 post.)

Get the gist? Above normal temperature anomalies tend to lead to below normal temperature anomalies, and vice versa. So now, let's take a look at what's happening here, with the most recent verification.

This image from the 10 millibar region in the stratosphere shows significant below normal temperature anomalies across much of Asia into the Northern Pacific, with above normal temperature anomalies stretching from the United States into Western Europe, with another swath of warm temperatures in East Asia on November 28th, 2013. Let's see how surface temperatures for December 7-10 are showing up, as the 2-4 week verification window from November 28th of December 14-28 is upon us.
It's no coincidence that we saw strong above normal temperatures across the North Pacific in response to those below normal stratospheric anomalies in late November. The warm stratosphere in the United States shows up as below normal temperature anomalies, fitting in to the STI's definition. Also, note how Western Europe shows up as below normal, and even a portion of East Asia getting in on the cold weather. Can you see how the index is verifying?

Now, take a look at this image of upper stratospheric temperature anomalies for December 7th. We see a strong body of above normal anomalies in the United States, as well as Central/Eastern Europe into East Asia. Significantly below normal anomalies are observed across Canada, the North Pacific and far northeast Asia. 

If we take that verification window from the late November warming (December 14-28), we can expect that timeframe to be colder than normal in the US. With the current warming intensifying in the image immediately above, we can now expect continued cold weather in the December 21-January 4. Depending on how long the warming in the United States lasts, we could continue to see cold weather well into January. It is tough to tell the intensity of the cold, but based on verification stats, it appears clear that the United States should see at least some cold weather.