August 4, 2016 – Cooling to near or below normal today through early next week. Slight chance of an afternoon shower or thunderstorm over the Coastal and Northern mountains Friday and Saturday.
Short term discussion (Today through Sunday)
A low off the Pacific Northwest coast extends a trough just offshore from NorCal. This synoptic pattern brings cooler temperatures and increased relative humidity through the weekend. High temperatures look to range from the mid 80s to lower 90s for the Sacramento region with the remaining valley areas cooling to the mid to upper 90s. Winds will likely be moderate through the Delta and over ridges due to the tight onshore surface pressure gradient. The SFO-SAC gradient had its diurnal peak of around 4 millibars prior to midnight.
Friday and Saturday will also bring more instability, in particular the far northern coastal range up through Western Shasta County. Moisture appears limited at this time but we will have to keep an eye on that area. The better chance for any thunderstorms looks to occur late in the day on Saturday and Saturday evening for those same areas.
Extended discussion (Monday through Thursday)
Upper level trough will linger across the region next week. Onshore flow will continue with temperatures near or a few degrees below normal. High temperatures will be in the 90s for the Valley and 70s in the mountains. At this point, forecast looks dry through the period as any moisture stays far to the north.