Cooling trend this week. Smoke from area wildfires will continue to impact portions of interior NorCal. Late-day thunderstorms are possible over the northern Sierra Nevada through the middle of the week.
Discussion
Mostly cloudy skies cover interior NorCal as moisture from Kay remains over the region. A few sprinkles, or light showers, persist to the north of Sacramento as a short-wave off the coast approaches. Current temperatures are running as little milder, and RH’s a little drier, compared to 24 hours ago. Readings range from the upper 60s to upper 70s across the Central Valley.
A few sprinkles will linger across the Sacramento Valley this morning, then scattered showers and thunderstorms are expected over the northern Sierra and southern Cascade Range this afternoon into this evening. Some brief heavy showers will be possible, but the threat of heavier rainfall will likely remain to the southeast of the forecast area.
Smoke from the Mosquito Fire, along with the clouds, will continue to affect temperatures today with highs expected to be similar to Sunday’s.
The trough over the eastern Pacific gradually moves over the West Coast this week pushing moisture further to the east and resulting in cooler temperatures and higher humidity as onshore flow takes hold.
The shower and thunderstorm threat will retreat to the Sierra south of Tahoe on Tuesday, and will be well to the southeast of the region for the remainder of the week.
Highs will be around 10-15 degrees below average by mid-week. Smoke is also expected to be mostly pushed to the east.
Extended Discussion (Friday through Monday)
Long wave trough off the West Coast deepens through the extended period as short wave trough from GOA drops south. Models/ensembles differ with depth and progression leading to some forecast uncertainties. Forecast for now following NBM which has potential for some showers over northern portions of the forecast area Sunday. High temperatures expected to be below normal.