COLD RAINS WET THE PLAINS

mage of rainfall totals, in inches, for December 9-11, 2007. The rainfall data is courtesy of the Texas Tech West Texas Mesonet and the National Weather Service. Click on the image for a larger view.
Image of rainfall totals, in inches, for December 9-11, 2007. The rainfall data is courtesy of the Texas Tech West Texas Mesonet and the National Weather Service. Click on the image for a larger view.

The combination of an approaching upper level storm system, strong low level forcing over a stagnant dome of cold modified arctic air at the surface, and abundant moisture helped produced widespread rainfall across the region. This storm system was particularly problematic from a forecaster's standpoint in the fact that the exact magnitude and duration of the shallow cold air was tough to gauge. This was compounded by the fact that there was quite warm air just above the surface (approaching 50F). Thus, it was know that any precipitation that fell would be in the form of liquid. However, it was unclear whether or not there would be sufficient cold air at ground level for the falling liquid to freeze on contact.

As it would eventually turn out, there were a couple rounds of showers, isolated thunderstorms, and plenty of drizzle that did fall to the ground with temperatures at or slightly below freezing. Thankfully, though, the relatively warm ground coupled with the fact that the temperature never plunged much below the 32 degree mark help mitigate possible icing problems. Although there were reports of some light icing, primarily on trees, vehicles, fences, and grass, the roads for the most part remained wet. Overall, the majority the precipitation fell as a cold rain, with temperatures just slightly above freezing.

The heaviest of the rain fell over two periods. The first heavier swath of rain fell over the western part of the area early on Monday, with temperatures in the middle 30s. Then, the second more widespread batch of showers and thunderstorms moved up over the area from very late Monday, continued through the overnight hours, before exiting the region to the east by around noon on Tuesday. As this heavier precipitation moved in, most locations climbed to just above the freezing mark. Hence, the South Plains for the most part lucked out, even though locations farther east from Oklahoma through parts of Kansas, Missouri, Iowa and Wisconsin were not so lucky.

After all was said and done, the South Plains, Rolling Plains, and southern Texas Panhandle saw the first widespread significant precipitation (most locations seeing at least 1/2 inch) in quite some time (aside from the Thanksgiving weekend snows across southern sections of the area). In fact, this was the first precipitation event tallying over a half an inch at the Lubbock airport since September 26th.


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