While El Niño disappointed California last year, La Niña – a weak one – is delivering huge quantities of water this season and the height of it may be this week.
At least four feet of snow will fall on the Sierras by the weekend and a lot of rain will be falling elsewhere. The moisture is coming in so fast and furiously that there will be a significant flooding threat for the next couple of weeks.
First off, the snow that has fallen is already impressive:
We've gathered up the latest storm total snow reports with @NWSReno! Many FEET to come! #cawx pic.twitter.com/39ssSoC1UX
— NWS Sacramento (@NWSSacramento) January 3, 2017
And, add to that through Sunday with an additional 60"+ as shown here in the yellow shades:
That's just snowfall for the week. There's also a lot of rain to fall. Consider just this upcoming weekend for areas near Sacramento.
After Thursday, a warmer #atmosphericriver will bring higher snow levels & heavy rain this weekend. Heightened concern for flooding. #cawx pic.twitter.com/pDy4S1dGUd
— NWS Sacramento (@NWSSacramento) January 3, 2017
The rate at which the moisture is falling, more than 2-inches per hour in some cases in the mountains, is a serious threat to travel and will become a flooding risk throughout the weekend and for the next week at least.
Considering all water, rain and snow, here is the total precipitation that may fall through Sunday evening:
Yes, that's showing us 3 to 5 inches off the mountains and nearing 20 inches on the mountains.
This will tremendously improve the drought situation across northern California which sits near extreme levels toward central and southern regions.
Snowpack in the Sierras, to date, has been below average. This week's flow of plentiful tropical moisture will boost those averages.
Further, with snowfall chances continuing the snow totals from now to mid-January may well surpass 100". Rain chances, albeit not as intensely, will continue through the next two weeks also. Some of the lower country will close in on 5 to 10 inches of rainfall.
Southern California won't have these huge precipitation totals, but even far southern counties of the state may see upwards of an inch of moisture through the mid-month.