US

Weather Underground Forecast for Tuesday, December 15, 2009.

Two weather systems will produce unsettling weather activity in the Western and Eastern regions of the nation.

In the West, a strong Pacific front will hit the Pacific Northwest and northern California with significant onshore flow and moisture on Tuesday. Energy along the front will combine with rich Pacific moisture to produce swaths of lower elevation rainfall and high elevation snowfall throughout the regions. Gusty winds will accompany precipitation throughout the day. Precipitation in northern California will spread southward into Monterrey Bay. A weak ridge of high pressure will keep showers from spreading into southern California. Ridging will also translate into warmer and drier weather condition in the south.

In the East, low pressure over the Great Lakes will continue to produce a mix of lake effect rain and snow showers as it shifts into the Lower Great Lakes and the Northeast on Tuesday. The heaviest snow totals are expected to develop to the east of Great Lakes. Meanwhile, an associated cold front stretch across the Mid-Atlantic and the Southeast. Moisture from the Gulf of Mexico will mingle with energy along this front to produce another round of light showers and thunderstorms.

Elsewhere, high pressure in the Central US will keep a frigid airmass locked over the Plains and the Midwest.

Temperatures in the Lower 48 states Monday ranged from a low of -32 degrees at Jordan, Montana to a high of 87 degrees at Naples, Florida.