Tuesday, December 20, 2011

Southwest Storm

Yesterday morning, a deep atmospheric trough covered the western U.S., its leading edge stretching from southern New Mexico to Upper Michigan. As cold air poured southward within this dip in the jet stream, a powerful storm developed along its southern rim, sweeping moisture up from the Gulf of Mexico.

By later in the day, the storm had moved into the northern Texas Panhandle and its central pressure was falling. Strong, counterclockwise winds raked the Southern Plains and, northwest of the cold front, blizzard conditions developed across northeast New Mexico, southeastern Colorado and southwestern Kansas. Ahead of the front, Gulf moisture was streaming through the Midwest, igniting thunderstorms in northeast Texas and heavy rain across eastern Oklahoma, eastern Kansas and most of Missouri.

This morning, the storm has weakened and its center swirls over western Oklahoma. High pressure, dropping southward within the trough, has shut down the snowfall and has shoved most of the rain to the south and east; here in central Missouri, a light drizzle persists, driven by a raw east wind behind the front. While this system is abating, another storm, forecast to push through the Heartland later this week, may produce a White Christmas for those of us in the Midwest and Northeast.