The weather pattern all year has been one that features a lot of blocking across Canada which has largely kept the eastern U.S. in a trough. As a result, the eastern part of the nation has been cool and wet, while the western part of the nation has baked. The consistency of this pattern for the first 8 solid months of the year has been pretty amazing. The last cool summer similar to this was nine years ago, when the Lexington official reporting station never hit 90°F the entire year.
Summer 2013 is starting to wind down now. Meteorological autumn begins in just 20 days. This has led many including myself to start wondering what the end of the year may bring. If this pattern that has been locked in all year were to remain in place going into late autumn and early winter, we could be looking at ferocious winter weather with snow and very cold weather being likely. In fact, the summer I mentioned earlier resulted in a massive snowstorm just three days before Christmas 2004 in which Louisville saw two feet of snow and the Lexington area got in on some of the action as well. So with 2013 going the way of the unusually cool and wet summers it does make you wonder what could by lying ahead for us.
On the other hand the amazing consistency of the pattern we’ve seen is also what makes me think it will break up soon. It’s just a matter of time until the blocking breaks up and allows the jet stream to start moving around again. Interestingly, this is what the GFS model is currently showing for the second half of August. It lifts the jet northward, and takes the flow across the United States into a zonal setup. Basically, this just means that you don’t have huge ridges and troughs…the flow is simply west to east across the nation. This would result in a more stagnant airmass, as well as an increase in temperatures for us and a lack of rainfall compared to what we have been seeing.
The question of course becomes: Is this a temporary switch to more average summer weather at the very end of summer or is this the beginning of the next major pattern flip? That is the huge question because again, if the current pattern were to take us into winter we’d have big problems. But if this switch at the end of August is the beginning of an overall pattern flop, then winter 2013-2014 will be anybody’s guess. Time will tell and of course I’ll be watching for signs. In the meantime, it appears that summer is going to give us one final attempt at mustering up some hot and humid air to close out the season for 2013.
-Shawn
