December 3, 2018 – Chances for light rain and snow Monday night continuing through mid-week. A stronger system may impact the area early next week bringing heavy snow.
Discussion
Early this morning, northwest flow over Northern California persists as the main upper ridge remains west of the CONUS. Temperatures in most of the Valley have stayed steady in the mid-30s with fog formation already noted at locations up to MYV. Satellite indicates some scattered high clouds beginning to move over the northern portion of the Sacramento Valley, although these look to do little in the way of mitigating temperatures. There is a concern some locations may not reach freezing by early morning due to the higher dewpoints.
An upper low makes its way toward California late tonight bringing chances for rain and snow mainly to higher elevations. QPF amounts are less than a tenth of an inch making any impacts of this first round of weather minimal. The better chances for precipitation look to be Tuesday into Wednesday, although models have been trending this system further south than previous runs. Once again, any rain/snow looks to be light at this time with the average snow totals through Wednesday around 2-6 inches, with some locally higher amounts. Snow levels range from 2500-3500 feet.
The upper low begins to move south of the area by Thursday and skies will begin to clear by the afternoon.
Extended Discussion (Friday through Monday)
Drier weather returns Friday as shortwave ridging develops. The potential for wet weather on Saturday is dwindling, with a frontal system moving inland into the Coastal Range and southern Cascades and weakening as it runs into the ridge. This should mean little potential for precipitation over most of the area until later Sunday into Monday as a stronger system arrives. This has some potential to impact mountain travel with snow early next week, and bears watching.