US

Weather Underground midday recap for Monday, December 14, 2009.

The Central US began the work-week with frigid temperatures on Monday as an Arctic airmass moved into the region. Bitterly cold Arctic air from Canada plunged southward behind an exiting frontal boundary over the Plains and dampened daytime highs in the Central and Northern Plains. As the frontal boundary dropped southward, high pressure filled in behind the disturbance and aided in dampening daytime temperatures to well below seasonal averages.

Meanwhile, a wave of low pressure along the head of this frontal boundary advanced northeastward into Upper Great Lakes by the afternoon. Energy associated with this low combined with warm lake moisture to produce areas of light snow and freezing fog in Wisconsin and Michigan.

Elsewhere in the East, a frontal boundary along the Gulf Coast continued to spark areas of light to moderate showers, heavy rainfall, and thunderstorms in the Southeast, while high pressure returned drier weather conditions to the Mid-Atlantic and much of the Northeast.

Quieter weather conditions developed throughout much of the West on Monday as a wave of high pressure dominated weather activity through much of the afternoon. Onshore flow along the coast increased as a large eastern Pacific storm advanced closer to the Pacific Northwest and northern California shorelines.

Temperatures in the Lower 48 states Monday have ranged from a morning low of -31 degrees at Jordan, Mont. to a midday high of 87 degrees at Naples, Fla.