Pacific

Weather Underground Forecast for Monday, December 14, 2009.

A cold and fairly active weather pattern will grip much of the nation on Monday.

Cold temperatures are expected throughout the Central US as a cold airmass from Canada surges southward behind an exiting frontal boundary. In addition to this frigid airmass, high pressure will fill in behind the front and aid in dampening daytime temperatures to below seasonal averages. Temperatures in the Northern Plains will be restricted to subzero values, while highs in the Central Plains are expected to reach into the teens and twenties. Expect bitterly cold wind chills during the early morning and evening hours.

Meanwhile, a wave of low pressure along this boundary will crank out light to moderate snow showers as it advances into the Great Lakes on Monday. The most significant amounts of snowfall will blanket areas form eastern Iowa through the Upper Peninsula of Michigan.

Elsewhere, a weak frontal boundary along the Gulf Coast will continue to spark areas of showers and thunderstorms in the Southeast, while high pressure returns drier weather conditions to the Mid-Atlantic and much of the Northeast. Out West, another mix of precipitation will blanket the Pacific Northwest as a disturbance drops in from the north. The majority of California will experience drier weather conditions during the afternoon. Showers are expected to return to northern California during the evening hours.

Temperatures in the Lower 48 states Sunday ranged from a low of -21 degrees at Westby, Mont. to a high of 87 degrees at Fort Pierce, Fla.