March 22, 2021 – Mostly dry weather this week with a slight chance of mountain showers Monday and Thursday. Warmer temperatures expected most of this week. Breezy to locally windy Tuesday into Wednesday morning.
Discussion
Strong upper level ridging remains in place over the eastern Pacific with California situated on the downstream edge. Satellite data is showing high clouds streaming into NorCal early this morning ahead of a weak weather system. This system is expected to slide south along the flow from the PacNW into Nevada and Arizona today through tomorrow.
Latest model guidance has shifted the system to the west just enough that chances for scattered mountain showers have increased for today and tonight. Any precipitation is expected to be light with limited rain or snow accumulation. Snow levels will be around 5000 to 6000 feet.
The main impact with this system will be breezy winds Tuesday into early Wednesday as surface pressure gradients tighten as the trough moves south. Strongest winds expected in the Valley Tuesday morning through Tuesday evening. Strongest winds then shift to the mountains Tuesday evening through early Wednesday.
MFR-SAC gradient is forecast to tighten to around 10 to 11 mb Tuesday through Tuesday evening which could result in north wind gusts in the Valley up to 25 to 35 mph. SAC-RNO gradient forecast around 8 to 9 mb Tuesday night which could result in easterly wind gusts in the mountains up to 35 to 45 mph, locally higher in wind prone areas.
Otherwise upper level ridging expected through midweek. Ensembles continue to indicate another trough sliding south through Nevada and the Great Basin region Thursday. However, at this point it remains far enough to the east that precipitation chances will be limited. Another round of breezy winds are possible with this passage, though they don’t look to be as strong as Tuesday.
Temperatures this week will climb under the high pressure. Temperatures will remain right around normal today and Tuesday before rising a few degrees for midweek. Valley temperatures are forecast right around 70 degrees on Wednesday.
Extended discussion (Friday through Monday)
A dry and mild weather pattern is favored by the ensembles for NorCal later this week into early next week as high pressure dominates.
Highs will be around 10-15 degrees above average, and the first 80 degree readings of the season will be possible across the Central Valley over the weekend.