SACRAMENTO, Calif. — An incoming low pressure system from the north pushes into Northern California on Sunday, beginning a pattern shift and ending the stretch of sunny and seasonal weather.
The North Coast and Coastal Range are already seeing light rainfall as of Sunday morning.
Showers arrive
By lunchtime to mid-afternoon, the front will arrive in the valley, keeping temperatures in the low to mid-70s and bringing a very slim chance for sprinkles to the valley floor. As of Sunday morning, however, rain chances are not higher than about 20%.
By late afternoon Sunday, the cold front and associated showers arrive in the Sierra. This is where the majority of the impacts will be, with rain chances mainly north of Highway 50 and a dusting of snow possible along the highest passes of Highway 50 and Interstate 80.
Gusty winds will pick up Sunday with the cold front passing through. Valley gusts could be up to about 20 mph with gusts in the Sierra of 40 mph or more expected.
The best chance for a dusting of snow is going to be tonight into Monday, then again Monday evening into Tuesday morning. Snow totals on the passes of I-80 and Highway 50 are very likely to be an inch or less, so travel shouldn't be extremely impacted but it will be slower going than usual.
Icy spots on the main highways are also unlikely, but patches of ice on side roads Tuesday morning aren't out of the question.
Models are still picking up on some light valley showers Monday afternoon and evening in the valley as the system exits the region. These showers would be very spotty and very light, with only a few hundredths of an inch of rain falling. Nonetheless, something to be mindful of Monday afternoon.
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Impact
In the Sierra, gusty winds could cause difficult driving conditions as well as blow around loose objects. Overall, Sierra rainfall totals will be on the lighter side. Areas that see the highest totals are likely to be north of I-80, with up to about a half-inch of rain expected.
On Monday morning, Monday night and Tuesday morning, there is potential for some flurries and light snow above 6,500 feet that could stick to the high passes. It's unlikely that truly disruptive winter weather will develop, but certainly an inch of snow or less is quite possible.
Be prepared for slower travel across the high passes. High temperatures on Monday will likely be in the 30s and 40s.
This is not going to be a major rain or snow storm. Even in the Sierra, impacts will be minimal. Chain controls are not anticipated. Frankly, if this storm was occurring in January or February, this would not be a Weather Impact Alert.
The main reason for this alert is because it is a significant pattern change from what we've had most of October.
In the valley, even fewer impacts — if any — will be present to start the workweek. Rainfall totals will be less than a tenth of an inch across the valley, with many areas only seeing a hundredth of an inch or less. Bring an umbrella with you if you'll be out Monday evening, as that looks to be the best chance for some light showers.
Regardless of whether or not the valley sees showers, much cooler temps will be present all week. Highs in the middle to upper 60s are expected from Monday through to the weekend!
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Bring a jacket
Be ready for a significant pattern change, especially if you're in the Sierra. A period of cooler weather with showers and flurries is expected to start the week. Have your warmer jacket ready and give yourself some extra time driving on Monday and Tuesday morning.
Again, this is not a major storm by any means, but it is a major pattern change. We've been in the 50s and 60s in the Sierra and 70s and 80s in the valley. That's changing in a big way starting Monday. Sierra highs will only be in the 30s and 40s to start the workweek.
In the valley, not much needs to be done. Just remember cooler temperatures in the 60s are expected during the afternoon each day this week so you'll need to dress a little warmer.
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