Dry weather with sunny days and cool overnight temperatures continue. Valley frost and fog possible in the overnight and morning hours through Saturday. Precipitation returns by Sunday and persists into early Monday with minor mountain travel impacts and light valley rain. Potential for freezing overnight lows behind the system.
Discussion
Strong high pressure will continue over the region today. Winds have been staying up tonight helping to keep temperatures warmer in the Sacramento valley. Light winds in the San Joaquin valley will allow for better cooling and for a few patches of fog to develop this morning. Wind gusts have remain locally strong overnight for the western Delta with gusts in the mid 30s while max gusts in the mountains are around 30 to 45 mph for some of the wind prone areas with local stronger gusts over the peaks along the crest. Winds are expected to gradually decrease through the morning hours after sunrise.
Another warm day is forecast over the interior with most temperatures in the 60s for the valley and foothills. Friday the ridge will begin to break down as a weak wave drops down from the north over Oregon.
Morning temperature will bottom out in the mid 30s with some of the colder spots dropping into the lower 30s. Winds are also expected to shift direction and this may allow for more fog to develop in the central part of the valley for Friday morning compared with this morning.
By Saturday a weak dry wave will have passed through the region with this feature forecast to be a little further east today than yesterday and keeping the mountains dry. The main change will be in the cooler air the system advects over the region for the day.
Saturday night into Sunday a stronger cold system will rapidly move into the region. Models have moved up the timing of this system descending into the region. Not a lot of precipitation is expected and models have decreased precipitation from the earlier runs. Less then a tenth of and inch is expected in the valley and less than half an inch in the mountains.
The system is moving through rapidly and may clear the area by Monday morning.
Extended Discussion (Monday through Thursday)
Upper level trough will be pushing into the Great Basin for the start of the extended period. This will leave lingering light showers in the mountains on Monday. Additional accumulation with these showers will be limited.
We will also see some northerly winds develop on Monday but at this point they don’t look too strong.
Cold air will also build in behind this trough along with upper level ridging. Daytime highs will run 7 to 15 degrees below average with cold overnight lows.
Tuesday and Wednesday morning we will see a 65-95% chance of temperatures falling to 32 degrees or less across the Valley and a 20-70% chance for 28 degrees or less. Right now it doesn’t look like we will set any new daily record low temperatures but some area will be close both Tuesday and Wednesday.