August 22, 2016 – Continued warm and dry except for isolated showers and thunderstorms today. Warm temperatures will continue for today but will be slightly cooler than Sunday thanks to an upper level trough to our north. For this afternoon, we are expecting more thunderstorms to develop near the Sierra crest and eastward.
Discussion
Clear to partly cloudy skies across interior NorCal early this morning. A few light showers and an isolated thunderstorm or two are present across the southern portion of the forecast area as the region is in an area of weak flow aloft between a stronger trough moving through the PacNW and a very weak low off the central California coast.
Evidently, we’re seeing just enough lift to trigger some isolated showers and thunderstorms early this morning over the northern San Joaquin Valley and Motherlode as there is plenty of mid-level moisture and elevated instability overhead. By this afternoon, appears the focus of activity will shift back to the higher elevations where daytime heating with result in more storms along the Sierra Crest.
More moderate temperatures are forecast for interior NorCal this week as a weak trough hangs back across the region and some onshore flow continues. Most late day deep convection is expected to occur to the east and south of the region. Temperatures are expected to be close to average for late August.
Extended discussion (Friday through Monday)
Models show upper low off the Central CA coast Friday then diverge on how quickly it progresses through over the weekend. Deeper system then progged to approach the West Coast early next week. Main effect will be slight cooling over the weekend with high temperatures cooling to slightly below normal then returning to near normal early next week.