Below normal temperatures will continue through the holiday weekend. Temperatures will then gradually warm through the week. Gusty onshore today and tonight, becoming locally breezy in afternoons and evenings next week.
Discussion
Generally clear skies prevail throughout most of interior northern California this early Saturday morning. GOES-West nighttime microphysics imagery does show stratus beginning to develop in the Sacramento Valley. Breezy onshore winds blowing through the Delta is helping to advect Pacific-sourced moisture inland, allowing for the onset of the stratus development.
Compared to 24 hours ago, surface relative humidity values are running anywhere from 10 to 30% higher. Sacramento Mather Field (KMHR) started reporting broken low clouds as early as 11 PM Saturday. As the night progresses, do expect these low clouds to expand in coverage around the Sacramento Metro Area. Any low clouds will mix-out in the mid/late morning hours.
Longwave trough continues to reside just west of California. This trough has been responsible for the below normal temperatures over the past few days, and will continue to influence our weather through the Independence Day holiday.
Highs this afternoon will struggle to get out of the upper 70s in/around the Delta, with the rest of the Valley stuck in the low/mid 80s. For comparison, normal June 2 highs are 93 deg F in Downtown Sacramento and 98 deg F for Redding Airport. An embedded shortwave trough in the longwave, cyclonic flow will push through the northern quarter of the Golden State today, providing another chance of some afternoon showers to parts of Shasta County. Think the best chance of any thunderstorms will be to the north in Siskiyou County.
While today’s winds will remain breezy out of the south/west, they shouldn’t be as strong as Saturday’s winds.
Temperatures on Independence Day will fall within several degrees from Sunday’s highs with occasional south/west winds redeveloping again during the afternoon/evening.
While humidity values will remain elevated and in good shape through the weekend, always, ALWAYS be smart and safe around any sources of spark/flame. The vegetation is very dry throughout much of the region, and small fires can quickly take off, even with an onshore breeze.
Another shortwave will impact far northwest California on the Fourth of July, providing an opportunity for isolated showers and thunderstorms for the Coastal Range and Shasta County. Gradual warming trend will begin for northern California on Tuesday with widespread middle 80s for the Valley. The Northern Sacramento Valley will be flirting with the 90s once again by Wednesday.
Extended Discussion (Thursday through Sunday)
Long wave trough remains off the West Coast as downstream upper ridging begins to build westward through the week. This will result in a gradual warming trend through the extended forecast period. Highs in the Central Valley warm from the upper 80s to lower 90s Thursday to mid to upper 90s Sunday. Locally gusty S-W wind possible during the afternoons and evenings.