In the Summertime, when the weather is high
You can chase right up and touch the sky...
Yes, the opening line from the old Mungo Jerry tune says it all! The time has come to peer into the crystal ball and see what Summer 2009 has in store for us. One thing I feel confident about as we enter the season: It will NOT resemble recent summers that have given us moderate to severe--or for that matter, historic droughts, a la 2007. This season is already shaping up to be a different animal. Why do I think that? Here are some of the reasons:
1. THE MOIST SOILS: As I post this, Bowling Green is running a rainfall surplus of nearly 4" heading into late June. That's opposed to a deficit of that much (or in some cases more) in the last several years. This additional rainfall, of course, leads to a richer, more moist soil. That in turn leads to more evaporation and evapotranspiration from the grasses, plants, and vegetation, which in turn leads to generally cooler surroundings. Evaporation is a cooling process, therefore the sun has to work a little harder to heat up the ground when it is wetter. I believe this is a big reason why we will likely fail to hit the 100 degree mark this summer. On the flip side, though, more moisture means more humidity in the air, and that makes hot days feel much hotter. Don't get me wrong; we will have our fair share of 90 degree days this season which, at times, may yield to "feels-like readings", aka heat indices, of 100 or better.
2. UPPER TROUGH: The jet stream is also important in shaping up our summer patterns. It's not uncommon for the upper air winds that comprise the jet stream to retreat into Canada during late June, July and August. In the last couple of summers, however, high pressure ridging developed over the southeastern U.S. was responsible for many, many sunny and scorching days (especially in '07). Contrast that with Summer 2004. That season was noteworthy for its unusually low number of 90 degree days (only 9 for Bowling Green all year) and for its unusually high number of very cool days (several instances of record lows and record low high temps late July through early August that year). The culprit? Frequent dipping of the jet stream southward over the East (a trough). That brings with it a northwesterly flow, often taking the edge off the heat but keeping the weather pattern quite active, sometimes stormy. With that in mind, I think this summer will more closely resemble 2004, though perhaps not quite as cool.
So in summation: I am thinking temperatures for June, July and August will average out a bit below normal overall by about 1-2 degrees). I believe we will have somewhere between 15 and 25 days with temps 90 degrees or higher, which is below normal (we usually experience 32 of those in Bowling Green in a summer season). I also believe each summer month comes out above average for precip, likely being our wettest season in five years.
Thanks for reading,