Get the sweaters out for Sunday

Sept. 22, 2011     

Tahoe and most of the Sierra will be under a complex, changing weather pattern this weekend that's going to bring us a little bit of everything.

We will begin under the continued influence of an upper level ridge of high pressure that has brought warm temperatures to the Basin for much of this week. Highs today could reach the 80s in parts of the Sierra. Warm upper level temperatures should keep thunderstorms to a minimum as a they will strengthen the middle level cap and prevent those cumulus clouds from rising too much.

On Friday an upper level low will begin to move into California from Mexico, bringing clouds and moisture to the Sierra. This will increase the chance of thunderstorms, starting in the south, and keep Friday's overnight lows on the warm side. But by Saturday the afternoon highs will be trending down. While we will see more clouds and probably more thunderheads, the storms should be scattered and not a major threat.

By Sunday the Sierra will begin to feel the effects of a different weather system, a trough of low pressure arriving from the northwest. This won't be a winter storm, but the clouds it brings will be part of a cold front and not the same afternoon build-up we typically see in the summer. High winds and cooler temps are likely, but most of the rain from this system will fall on the coastal range, with little or no threat of showers as far east and south as Tahoe.