Thanks to a deep atmospheric trough that has nosed its way from Canada to the Gulf Coast, we have experienced raw, March-like weather in Missouri over the past two days. Low clouds, drizzle, intermittent cold rain and temperatures in the 30s and 40s F have set back the seasonal clock, temporarily denying us the annual rewards of early May.
Snow has fallen across western Missouri and northwest Arkansas and, this morning, heavy rains are pushing northward along the eastern edge of the trough. Trapped within its chilly realm, those of us in central Missouri will endure another day of cool, cloudy weather with scattered showers; meanwhile, residents of northern Michigan, Upstate New York and Maine will enjoy a sunny May weekend, with highs in the seventies.
Such disparate conditions across our country, reversing the usual effect of latitude, illustrate the potent role of the jet stream as it undulates through the season. Within its dips, cold, Canadian air pours southward while, within its northerly curves, warm air streams up from the south. By June, the jet begins to settle down, leveling out across Canada and setting the stage for the relentless heat of an American summer; it is then that we long for another cool trough to invade the Heartland.
