Northern California's dry streak coming to an end as rain, snow set to return
The start to December has been quiet across Northern California with no rain in the forecast since late November. But, the dry streak is about to come to an end as the storm door reopens allowing for multiple storm systems to move in this week.
Wednesday will stay mainly dry and sunny. Clouds increase come the afternoon as the first storm system moves in by Wednesday night.
Two storm systems will impact the region mid-week through the weekend with more rain and Sierra snow chances. By early next week, we are watching the potential of a third storm moving in on Monday.
Northern California Storm Door Reopens
Over the last week, most of California has sat underneath a large ridge of high pressure. This has blocked any incoming storm systems, kept the region dry, and pointed the storm track to the north.
By Wednesday, high pressure begins to break down allowing our next storm system to move in.
The first area of low pressure system will be fast-moving but it will be just enough to open the storm door open and keep active weather around over the next few days.
Storm #1: Wednesday PM to Thursday
This fast-moving storm system will arrive during the day on Wednesday, impacting the Coastal Range, Bay Area, and Northern Sacramento Valley before arriving in the greater Sacramento area after 9 p.m.
Rain begins to fill in across the Valley and snow across the Sierra, Wednesday night through Thursday morning. We are expecting our heaviest precipitation while many are sleeping.
By Thursday morning's commute, scattered showers continue across the valley and foothills as the storm continues to move east.
With recent model runs, rain and snow amounts have trended higher as a second wave of moisture arrives by the afternoon. 0.25-1'' of rain is expected in the valley. Drying out by Thursday evening.
Snow begins across the Sierra around 4,000-5,000 feet in elevation. Snow levels will drop quickly as the storm begins. A Winter Weather Advisory has been issued starting at 10 p.m. on Wednesday until 4 p.m. Thursday for elevations above 5,000 feet.
Snow totals have trended higher as of Wednesday, with 5-12'' of snow now expected for elevations above 5,000 feet. Chain controls will be possible, especially on Thursday morning and afternoon.
Light snow showers will linger into early Friday before clearing.
There will be a brief break in activity from Thursday evening through early Friday before our second storm moves in.
Storm #2: Friday PM - Sunday AM
The wettest of the two storm systems this week arrives on Friday. The day will start mainly dry as clouds begin to rebuild.
Rain returns to the Northern Sacramento Valley through Friday morning before the main event arrives by Friday night.
Timing has been back and forth between models of starting earlier and later in the day on Friday. Right now, we can expect scattered showers through the late afternoon and heavier rain by evening on Friday.
This storm is tapping into an atmospheric river, a narrow plume of subtropical moisture to deliver heavy rain and snowfall at times.
Our heaviest precipitation arrives Friday night through Saturday afternoon. A good-soaking rain in the valley and foothills will be possible. Gusty winds will accompany the main front that moves in with gusts up to 30 mph in the Valley, and up to 40 mph in the Sierra.
Snow will begin across the Sierra just after 9 a.m. on Friday starting north of I-80 first, before spreading south.
This storm will have the potential to interrupt weekend travel plans, especially Saturday, with slick roads in the valley and chain controls over the Sierra expected.
Snow levels will rise as this storm moves in, but will start at 4.500 feet on Friday and climb to 5,000-6,000 feet on Saturday. Colder air moves in with the front Saturday night, dropping snow levels back to the 4,500 range.
If you had outdoor plans on Saturday, finding an indoor solution will be best as rain continues through Saturday into Sunday morning.
The highest rain totals will be north of I-80 as some areas in the northern Sacramento Valley will get up to 2 inches of rain.
Showers begin to taper off by Sunday morning, leaving Sunday afternoon dry across the valley and most foothill locations. A few lingering snow showers will be possible across the Sierra after sunrise.
The remainder of the weekend stays mainly dry before we're eyeing another quick storm system by Monday.
Storm Totals: Wednesday-Sunday
Rain and snow amounts will fluctuate with the timing and track of each storm this week. But adding up totals this week, these next two storm systems will help keep us on track to hitting our snowpack and water goals by next year.
Over the next five days, we are expecting our highest rain and snow totals along and north of I-80.
We could see some spots in the Northern Sacramento Valley reach 1-2 inches of rain, whereas closer to Downtown Sacramento up to 1.5 inches of rain is expected.
Amounts vary across the foothills as some areas north of I-80 will have the chance of seeing 2-3 inches of precipitation, with up to 2 inches of precipitation across central foothill spots.
Snow totals may also change as storms move in, based on changing snow levels.
By Sunday, expect 10-20 inches of snow across elevations above 5,000 feet. We could see up to two to three feet of snow across mountain peaks by Sunday. Periods of moderate to heavy snowfall are expected Friday through Saturday.
Be prepared for winter travel if your weekend plans take you over Sierra passes. Chain controls, delays, and closures are possible.
Next week's storm chances
One more storm system looks to slide in as we start next week. Early models show this moving in as early as Monday morning. Producing more scattered rain showers and more snow across the Sierra through Monday night.
This storm will be weaker than the one over the weekend and fast-moving like Thursday's storm. We are expected to dry out by Tuesday and Wednesday with partly cloudy skies and highs in the upper 50s through the afternoon.
After Monday, our pattern dries out again through mid-week, but another storm or two could be possible toward the following weekend.
Monday's storm timing and amounts are expected to change over the next few days so make sure to stay with the CBS Sacramento First Alert Weather team as we iron out the details.
