Portola Valley, CA

Weather Underground Forecast for Friday, February 10, 2012.

Expect active weather to move into the East on Friday, as a trough of low pressure moves from the Southern Plains and into the Eastern Valleys. Flow around this system will pull moisture and energy in from the Gulf of Mexico. This will produce scattered showers and thunderstorms over the Southern Plains and Lower Mississippi River Valley throughout the day. There is a slight chance that these storms will turn severe with strong winds and heavy downpours. The northern side of this system will push a cold front into the Midwest, which will move through the Great Lakes and into the Ohio River Valley. Expect light and scattered snow showers to develop along the front as it passes through northern Michigan and into the eastern Ohio Valley and the Central Appalachians. Warmer temperatures ahead of this system will allow for rain showers to develop in parts of the Mid-Atlantic states and the Tennessee Valley.

Out West, a weak trough of low pressure moves onshore from the Pacific Ocean, bringing some moisture onshore with it. This will produce more rain and high elevation snow showers over the Pacific Northwest. Some of this moisture will stretch southward into northern California, allowing for light rain and high elevation snow showers to spread into the northern Sierras.