May 30, 2018 – A significant cool down begins today and continues Thursday. Warming trend returns for the weekend. Afternoon and evening thunderstorms possible over higher terrain today and Thursday.


Skies are clear to partly cloudy across the region early this morning. Showers and thunderstorms are well to our east in Nevada.

Current temperatures are running around 5-10 degrees cooler compared to 24 hours ago in the Delta Breeze influenced areas (from around Stockton up to the Marysville/Yuba City area currently), but little change elsewhere yet as the initial front is moving through NW California.

Initial cooling will spread across the area today as onshore flow increases and the trough initiates synoptic cooling. The trough is reinforced by a short-wave on Thursday that will bring a second batch of cooler air southward. Temperatures Thursday will likely be around 20 degrees cooler compared to Tuesday’s highs.

Instability will be mainly over the Shasta County mountains/Lassen National Park area, and near the Sierra crest mostly south of Highway 50 today, and then mainly over the Shasta Co mtns/Lassen Park area on Thursday.

A warmup will follow Friday into the weekend as ridging returns to the area. Temps will reach into the 90s for the weekend as 850 mbs temps return to the low 20s Deg C.

Extended discussion (Sunday through Wednesday)

Stable flow aloft will keep warm and dry conditions across northern California Sunday and Monday. An approaching weak disturbance for the middle of next week should drop temperatures slightly, but no precipitation is anticipated at this time.