We have a busy weather day across NorCal!

10:10 p.m.

Rain turning to snow after midnight for the foothills. Snow level drops to near 1700 feet along I-80 and 2000 feet along HWY 50 by sunrise Friday morning.

Blizzard conditions are expected for the Sierra through 4 a.m. Friday with occasional whiteouts.

A Winter Storm Warning will remain in effect for the Sierra through 10 a.m. and until 10 p.m. for the lower elevations.

A slight chance of thunderstorms remains for the valley.

9:11 p.m. update:

Placer Sheriff has announced several areas are required chains:

6:10 p.m.

Lighter winds expected tonight for the valley with a few breaks in the wet weather. More to come tomorrow with a slight chance of afternoon thunderstorms.

The Sierra is still a mess with near whiteout conditions and a Blizzard Warning in effect through 4 a.m.

Snow level will lower to near 1200 feet by early Friday morning.

4:56 p.m. update:

According to CHP-Truckee, tractor trailers can once again travel on I-80.

3:41 p.m. update:

CHP says Hwy 89 is open again.

3:36 p.m. update:

Placer Co. Sheriff says Hwy 89 north of Tahoe City is closed because of a big rig crash.

2:53 p.m. update:

CHP says Intrastate 80 is re-opening to car traffic.

2:00 p.m. update:

Heaviest rain east into the foothills. Peak gusts have been near 45 mph. Wind Advisory is still in place until 8 p.m.

Heavy snow continues for the Sierra and a blizzard warning remains in effect until 4 a.m. with whiteout conditions. Continued road closures are likely.

1:10 p.m. update:

Caltrans reports Interstate 80 is now closed n both directions between Colfax and Truckee because of whiteout conditions.

Rain and snow showers continue today as a cold front moves through the area. The cold front will usher in cool temps and kick up our winds. The cooler air mass will drive down snow levels close to 2,000 feet.

We're expecting some slight clearing behind the cold front which could spark the opportunity for isolated thunderstorms this afternoon until early tonight. Any thunderstorms that develop could produce some small hail. An approaching low-pressure system will keep the threat of showers in the forecast through Saturday.

Afternoon Post:

Valley: Moderate to heavy rain until early transitioning to scattered showers later today. There's also a chance of thunderstorms - small hail, gusty winds, heavy downpours and lightning possible.

Foothills: Heavy rain and, depending on where you are, heavy snow. The snow elevation is starting off around 4500' falling during the day. Snow levels could reach as low as 1000-2000 ft. Winds will be gusty.

Sierra: HEAVY SNOW! Travel is not encouraged. There's a Winter Storm Warning, Blizzard Warning, & Avalanche Warning for the backcountry areas outside of established ski areas. Visibility will be limited at times because of the heavy snowfall and the strong winds. Chains controls are in effect. Travel will be slow and roads could potentially be closed.

A blizzard warning was issued for parts of the Sierra Nevada, where winds could gust up to 125 mph (200 kph) on the ridges and 40 to 60 mph (65 kph to 95 kph) in some valleys, the National Weather Service said. A blizzard warning is issued when winds of at least 35 mph are expected for 3 hours or more coupled with snowfall leading to whiteout conditions.

The heavy snowfall would help the snowpack, which is vital to the state's water supply and is only about a quarter its normal size for this time of winter.

The National Weather Service has issued a winter storm warning for much of northeast Nevada through noon Saturday ahead of a dangerous storm moving into the western part of the state. A winter weather advisory is in effect from 4 p.m. Thursday to 10 a.m. Friday for Reno, Sparks, Carson City and much of the Sierra's eastern front.

The Sierra Avalanche Center in Truckee has issued a backcountry avalanche warning for Greater Lake Tahoe area for the upcoming snowstorm.