February 8, 2021 – Dry weather with cooler temperatures expected today. Threat of mountain showers expected on Tuesday with widespread precipitation possible later in the week.
Discussion
Satellite imagery indicates high clouds spreading across most of the region early this morning. The clouds will work to limit much extent of early morning valley fog.
High pressure will begin to weaken across NorCal today as a series of short-waves drop down the west coast of Canada, then turn east through the PacNW and reinforce the eastern US trough. Combined with the increase in high cloud cover, highs today will be down around 5-10 degrees compared to Sunday ending the recent streak of unseasonably mild daytime temperatures across the region.
The weak system off the coast will continue to slowly approach the region today. It will bring some sprinkles, or light showers, to the higher elevations of the northern Sierra late tonight and Tuesday.
A better chance of more significant precipitation will develop beginning Thursday as the blocking ridge recenters northward into the Yukon and Northwest Territories allowing energy to undercut the ridge and move into NorCal. Still quite a bit of uncertainty regarding QPF as ensembles indicate quite a bit of spread on the amount and timing of onset. Stay tuned.
Extended discussion (Friday through Monday)
Pacific storm tracks through the CWA Friday followed by brief short wave upper ridging Friday night into early Saturday. Colder short wave trough pushes inland later Saturday into early Sunday with snow levels lowering into the foothills.
Showers decrease Sunday afternoon under short wave ridging then another wave rides the ridge into interior NorCal Monday.