Afternoon showers possible today, dry and warm starting tomorrow

May 19, 2020 – Showers linger today, mainly for the mountains and foothills. Most precipitation will be in the afternoon, including some thunderstorms. Snow above 7000 feet may cause travel delays. Dry weather and a warming trend are expected from mid-week onward, with above normal temperatures by the weekend.

Discussion

Upper level that brought an active weather pattern to the region on Monday is now centered over Lake Tahoe, moving eastward. Shower activity has been light and over the mountains, with dry weather elsewhere. The Winter Storm Warning over western Plumas County and Lassen Park was allowed to expire at midnight.

The low will be gradually exiting to the east today with northerly return flow over the area. This is going to keep showers in the forecast, mainly as instability increases in the afternoon over the foothills and mountains. Some thunderstorms are possible there but will be much less extensive than on Monday. Snow showers over the northern Sierra could bring a few more inches of snow above 7000 feet. This could cause periods of slippery roads at pass levels. The Winter Storm Warning there has been downgraded to a Winter Weather Advisory until 5 pm this evening.

Dry weather is expected on Wednesday as the trough pushes into the four corners region but an isolated shower or two will be possible at the Sierra crest in the afternoon. Short wave ridging builds in for Wednesday evening into Thursday with dry weather.

Cool weather will continue again today, with highs generally running 5-10 degrees below normal in the Valley and 10 to 20 below average in the mountains and foothills. This means lower 70s for the Valley. Highs return to near normal Wednesday through Friday, with Valley highs in the upper 70s to lower 80s.

Extended Discussion (Saturday through Tuesday)

Dry weather expected through the weekend under upper level ridging. High temperatures warm 5 to 10 degrees above normal by Sunday. Warming continues Monday into Tuesday with highs in the Central Valley in the lower 90s, with 70s to 80s for the mountains and foothills.