Southcentral

Weather Underground midday recap for Wednesday, December 23, 2009.

Widespread multi-level clouds spread from the Intermountain West through the Plains on Wednesday as a large trough of low pressure reached back into Arizona and spanned across the Four Corners, the Plains, and into the Upper Great Lakes. Energy from this trough produced areas of significant and/or persistent mixed precipitation throughout these regions and yielded to numerous Winter Weather Advisories and Winter Storm Warnings.

Another area of low pressure from Alberta Canada, also known as an Alberta Clipper, dropped southward into the Central and Northern Plains with a strong surge of cold air. Dynamics associated with this system and it's accompanying cold airmass created areas of light snowfall and freezing rain.

The combination of these two aforementioned systems are forecast to bring a major storm to the Great Lakes with more profound precipitation through the upcoming holiday.

Meanwhile, low pressure over the Central US will drew significant moisture from the Gulf of Mexico across the Gulf Coast. This high flux of moisture spread northward and produced areas of light to moderate showers and heavy rainfall with thunderstorms through the Mississippi and Eastern Valleys. Moisture also kicked up mixed precipitation in the eastern portions of the Central and Southern Plains.

Elsewhere, light snow fell across Northern Maine as low pressure exited into the Atlantic Ocean. On the opposite coast, mostly clear and quiet weather conditions persisted in the Pacific Northwest and California as a ridge of high pressure remains the dominant weather feature over these regions.

Temperatures in the Lower 48 states Wednesday have ranged from a morning low of -11 degrees at Mt. Washington, N.H. to a midday high of 81 degrees at Edinburg, Texas.