My meteorology friends and I have been using one word to describe 2013: boring. But I suppose that’s a good thing when you consider the shear lack of tornado outbreaks and big severe weather outbreaks across the nation this year. Here in the Ohio Valley region we’ve spent most of the year locked into a blocking pattern that has kept the flow mostly northwesterly. As a result, we’ve had above normal precipitation and below normal temperatures in every single month this year, minus February.
That’s all about to change, however. In my last write-up I talked about how this consistency in the pattern is what leads me to believe it will break up soon. Looking at the latest model data, that may be exactly what’s about to happen. The jet stream is starting to move around more now and going into October the GFS model is predicting the jet to go wild. A very wavy looking pattern, which we call a “meridional flow” pattern, is predicted to take shape in the coming weeks. When this happens, it shakes up the weather nation-wide.
I expect that the first truly cold air of the season is coming to the Rocky Mountains soon. We may hear the first echoes of the “S-word” mentioned by national TV weather personalities as some huge troughs begin to dig into the western U.S. Here in the Ohio Valley, Kentuckians can expect more variability in the weather with potential episodes of heavy rain and more frequent shots of colder air moving in.
Because of the cool, wet summer we just experienced I’ve been using 2004 as a good analog year to compare to when looking at what may be coming for the end of this year. This might not turn out to be a good year to use after all. In 2004 the 70s and 80s that we saw all summer continued through October. What was labeled as “cool” in July became “warm” by the time we were deep into fall. Winter ended up being mild overall, with one historic snowstorm around Christmas that mainly affected the Louisville area with a couple feet of snow, and another cold snap in late January, but otherwise temperate and rather dry. This year is starting to follow a different course already with the cool air of summer looking like it will turn into cold air sooner. You certainly cannot predict winter accurately from months away and I will not try. But the overall pattern this year will likely be colder and snowier than what we ended up seeing the last time we had a cool summer.
It should be fun to watch this play out. In the meantime, as the growing season comes to and end now we’ll all be on the lookout for that first frost of the season. If the GFS computer model is on to something, we might not have to wait too much longer.
-Shawn
