Thursday, December 27, 2018

A Brief December Spring

A potent winter storm, currently centered over northwest Missouri, is dropping heavy snow across the Northern and Central Plains.  Ahead of its cold front, spring-like weather has invaded central Missouri, courtesy of strong southeasterly winds that have brought mild, humid Gulf of Mexico air into the Heartland.

Heavy rains fell last night, leaving shallow pools across the regional farmlands, and the southerly flow has continued today, pushing afternoon highs into the lower sixties (F).  Our late December spring will be short-lived, however, as the cold front sweeps through the area this evening.  While we are expected to escape the snow, highs will remain in the thirties for much of the week.

Usually, the jet stream settles into a "zonal flow" by winter, preventing wide swings in the temperature range across Temperate Latitudes.  As our climate warms, however, a less stable jet stream appears likely and bouts of spring in winter will surely become more common.  What effects that will have on Temperate ecosystems remains to be seen.