Weather Underground midday recap for Saturday, December 15, 2012.

Three weather systems brought active weather to the nation on Saturday. A strong low pressure system advanced northeastward over the Central Plains and into the Upper Midwest and Great Lakes. This system created a warm front that stretched eastward and produced rain and snow showers across the Upper Midwest, while a cold front extended southward from this system and pulled moisture and energy in from the Gulf of Mexico. This allowed for showers and thunderstorms to develop ahead of the front as it moved form the Plains into the Lower and Mid-Mississippi River Valley. Severe storms have not yet developed, but this system has a history of producing strong and damaging winds, hail, heavy downpours, and even a couple of tornadoes.

Just West of this activity, a trough of low pressure advanced eastward from southern California and into the Desert Southwest. This brought abundant moisture in from the Pacific Ocean, and allowed for rain and snow showers to spread from southern California, over Arizona, and into Utah and Colorado. Heaviest snowfall was reported in northern Arizona on Saturday with totals from 4 to 8 inches above 5,000 feet, while up to 14 inches were possible above 6,000 feet. This Winter Weather Advisories have been issued across the region.

Further West, another trough of low pressure moved toward the West Coast and pushed a cold front onshore. This brought plenty of moisture onshore with it, and produced another round of heavy rain and snow showers for Washington, Oregon, and northern California. Snowfall totals ranged from 6 to 10 inches across the Cascades.

Temperatures in the Lower 48 states Saturday have ranged from a morning low of 1 degrees at Minot, N.D. to a midday high of 84 degrees at Brownsville, Texas