The Nation's Weather 12.14.09

By WEATHER UNDERGROUND (AP)

A mass of cold air moving south from Canada was forecast to push down temperatures in the central U.S. on Monday, with snow falling across the Great Lakes region and a mix of precipitation predicted to cover the Pacific Northwest.

High pressure was predicted to fill in behind the frigid Canadian air, holding daytime temperatures in the central part of the country below seasonal averages. In the Northern Plains states, temperatures weren't expected to rise above zero, while highs in the Central Plains states were forecast to reach into the 10s and 20s.

Bitter cold wind chills were predicted for the early morning and evening hours.

Meanwhile, a wave of low pressure was forecast to drop light to moderate snow showers as it heads across the Great Lakes. The heaviest snowfall was expected to blanket areas from eastern Iowa through Michigan's upper peninsula.

Showers and thunderstorms were forecast for areas of the Southeast, while high pressure was expected to return drier weather to the Mid-Atlantic and much of the Northeast. Most of California was expected to experience drier weather through the afternoon, with showers forecast in the northern part of the state Monday evening.

Temperatures in the Northeast were forecast to rise into the 30s and 40s, while the Southeast was to see temperatures mostly in the 40s and 50s, with highs reaching the 80s in parts of Florida. The Northwest was expected to see highs in the 40s.

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