Thunderstorms rumbled across Missouri overnight as the leading edge of a potent cold front dropped through the State. This morning, that front stretches from Upstate New York to Oklahoma to Montana and a wedge of cool, Canadian air has invaded the Plains and Great Lakes region. Our low in Columbia was 58 degrees F, typical for this past week, but the freezing mark has been reached along the northern U.S. border and, here in central Missouri, we expect a drop to 38 degrees by tomorrow morning.
This widespread chill is winter's first significant advance on the Heartland; the seasonal battle with summer has begun and will continue for the next few months. While we recognize spring and fall as distinct seasons, characterized by a host of natural events, they are, in fact, the products of a restless jet stream which engages winter and summer in a struggle for territory. Having settled in Canada for the past few months, the jet has taken a dip to the south, allowing chilly air to pool behind its broad sweep and igniting thunderstorms as the cool dry air undercuts the warm, humid air of summer's domain.
As it undulates across the country in the coming months, the jet sream will produce ridges of summer and troughs of winter; while not as extreme as the parent seasons themselves, these pockets will bring an alternating pattern of warm and cool weather to much of the country. Over time, the chilly interludes will begin to dominate and, as the jet stream settles near the Gulf Coast, winter will reclaim the Heartland. Until then, we'll enjoy the colorful foliage of autumn, the waves of migrant waterfowl and the crisp, invigorating weather of our slide from summer's oppressive heat to the depth of winter's chill.
