Jumat, 03 Februari 2012

A Spring Storm in Mid Winter

Here in central Missouri, we awoke to clear skies and temperatures in the low 40s (F), with light southeast winds. But to the west, a wall of dark clouds stretched across the horizon, the leading edge of a massive storm system that is centered over the Southern Plains. Ahead of the storm, Gulf moisture is flowing northward across the Heartland and, as the system approaches, bands of rain will move in from the west, a product of lift, atmospheric moisture and the clash of air masses. Rain should develop in central Missouri by early afternoon and is expected to persist for 24 hours or more, a welcome development for our parched landscape.

On the northwest side of this storm, the Gulf moisture is being whipped toward the Front Range as counterclockwise winds swirl around the central low. These upsloping winds cool as they rise in elevation and heavy snow is falling across Metro Denver, the foothills and the adjacent plains; up to 20 inches are expected in the city with higher amounts on the east slope of the Front Range. Since the primary jet stream remains up in Canada, the air will not be extremely cold (remaining in the 20s F) but the associated strong winds are producing blizzard conditions and parts of several Interstates have been closed.

As the storm pulls on to the east, this upslope effect will be lost and snow will be very limited in the Upper Midwest; here in Missouri, all precipitation is expected to arrive in the form of rain. Once again, the high riding jet stream will spare most of the U.S.; while we enjoy a mild winter, Alaska, eastern Europe and Russia, caught above the jet stream, have been dealing with heavy snow and frigid air. Indeed, our mild winter has nothing to do with global warming but, rather, reflects a stagnant weather pattern across the Northern Hemisphere.

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