Friday, August 30, 2013

Stratospheric Warming Event Taking Place

A stratospheric warming event is taking place as we round out the month of August. You may be wondering how the stratosphere can be experiencing a warming event because we are in summer and not winter. Truth be told, the stratosphere can warm at any time- the reason it warms so significantly in the winter and barely at all in the summer is because of just how dynamic the atmosphere is in the winter with the polar vortex, Arctic Oscillation and all that jazz.

Back to the point, the arrows on the images on the chart above show where this warming event is occurring. At the moment, we see the strongest activity placed between the 40N and 70N latitude areas. This corresponds roughly to the area between the southern Great Lakes and Mid-Atlantic to northern Canada when looking at the North American continent. Because this is a stratospheric warming event, I do anticipate a body of colder air to transition from the upper atmosphere down to the surface, just as what happens in a winter stratospheric warming event.

The question is, where will the cold air end up? Remember that the 40N - 70N area includes the rest of the world, and the effects of stratospheric warmings are not limited to North America. A quick glance at ensemble projections of the mid-level atmospheric height anomalies beyond the 10 day period shows a troughing pattern over the Great Lakes. This could clear the way for not only cooler weather created by the troughing pattern, but also, if the atmosphere cooperates, colder weather being shifted to the surface from this stratospheric warming event. But at of right now, this is all educated speculation.


Official 2013-2014 Winter Forecast Comes Out Tomorrow

The Official 2013-2014 Winter Forecast comes out TOMORROW at 12:00 PM Central Time.

Also coming out tomorrow at noon are the 20 pre-selected cities' winter forecasts, and the winter forecasts for the North Atlantic Oscillation and Arctic Oscillation. 

Winter is quickly approaching!