Autumn in July

An atmospheric trough, produced by a dip in the jet stream, has ushered cool, dry Canadian air into the American Heartland; overnight lows have fallen into the low 50s (F) while afternoon highs are topping out in the 70s.

This mid summer gift, arriving on the heels of hot, muggy weather, will certainly invigorate both the wildlife and those humans who enjoy watching them.  At Forum Nature Area, here in Columbia, birdsong has noticeably recovered from its summer suppression and visitors are unusually numerous for mid July.  Back home, many of our permanent avian residents are checking out the feeder (which I generally fill from October to April), seemingly fooled by the unseasonable chill.

No doubt, those who reject the evidence of global warming will point to this cool air incursion as further support for their entrenched position.  However, if they bothered to check the weather map, they would find that the trough is bounded by atmospheric ridges, bringing warmer than average conditions to the Pacific Northwest and Northeastern U.S; along the borders of the trough, thunderstorms delineate the clash of the air masses, producing some flooding in the East but bringing much needed rain to the Southern Plains.  Indeed, the undulating jet stream, rather unusual in mid summer, may be (at least in part) a consequence of our warming global climate.  Regardless of the cause, we'll enjoy the autumn-like weather while it lasts.