A cooling trend through holiday weekend. Slight chance of showers Friday evening into Monday over the Sierra, northern Sacramento Valley and surrounding mountains. Dry and breezy conditions return early next week.
Discussion
Delta breeze has brought significant cooling to the Southern Sacramento Valley with temperatures running about 10 degrees cooler than yesterday at this time. A brief period of stratus cloudiness will likely fill the Delta and Southern Sacramento Valley this morning. Main trough tracking through the Pacific Northwest over the weekend will extend south over NorCal. This will bring cooler conditions with periods of breezy onshore winds.
As the the system approaches expected scattered showers to develop over Shasta county Friday afternoon and spread south over the northern Sierra into Saturday.
A slight chance of thunderstorms will also be possible over Shasta county, the southern Cascades and northern Sierra Saturday afternoon and evening.
Ensembles and clusters show the upper low moving into the Great Basin Monday, as this occurs onshore gradients will reverse and become offshore. The EFI is highlighting portions of northern California for climatologically elevated north winds during the Monday-Tuesday timeframe with gusts up to 30 mph.
Instability appears to be on the low side at this time, so not expecting widespread thunderstorm activity or strong storms, but possibly some isolated small hail. Rainfall amounts are expected to be light with no precip in the Valley and less than 0.25 inches over the mountains. Snow levels will remain above 8,000 feet, so not expecting any snow at pass level or below.
This will likely bring fire weather concerns back to the area Monday and Tuesday. Valley temperatures warm back into the 90s by Tuesday next week.
Extended Discussion (Tuesday through Friday)
High pressure building inland Tuesday will bring some gusty north to east wind and warming temperatures. Upper ridge progress through Wednesday as next Pacific frontal system approaches.
Some associated cloudiness and cooling expected Thursday as baroclinic zone weakens and moves through. Secondary wave follows Friday with a threat of showers over the Shasta mountains.