Flooding and Heavy Snow in California, March 27 to 30, 2023

Name: Flooding and Heavy Snow in California, March 27 to 30, 2023
Start: 2023-03-27T17:00
End: 2023-03-30T06:15
Location: California

March 27 to 30, 2023 · NWS STO · 13 events in 11 counties and zones

Where it happened

Every event with a place to put it. Tap one for its entry below.

Tornadoes
Tropical storms and surge
Floods
Wind
Hail
Winter weather
Heat and drought
Cold
Fire, smoke and dust
Marine and coastal
Other

Open the live radar over this ground

The toll

Deaths: 1
Injuries: 0
Property damage: None recorded
Crop damage: None recorded
Events: 13

Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.

What happened

The episode as NWS STO wrote it up.

A strong winter storm brought moderate to heavy rain with with flooding of roadways, streams and creeks, with mudslides also reported. There was continued river flooding along the already elevated Sacramento, San Joaquin, Cosumnes, Mokelumne, and Tuolumne rivers. The storm brought dangerous mountain travel conditions with snow levels around down to 2000 feet, locally 1000 feet in Shasta County. Storm totals reached 1 to 3 feet of above 5000 feet. Winds gusted up to 35-50 mph in the Central Valley. In the mountains there were gusts up to 50 to 70 mph, which coupled with heavy snow, brought whiteout conditions. The were numerous road closures, including Interstate 80, Interstate 5 north of Fawndale, as well as State Routes 88, 89 and 299. Widespread trees down across the area blocked roads and caused power outages. There were thunderstorms on the 28th with a funnel cloud reported visible from the tower at Redding Airport. There was a fatality reported when man was trapped by a collapsed snow bank next to his home.

What forecasters said that day

The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Sacramento, CA wrote its last area forecast discussion before the first event at Mar 27, 12:45 PM PST, 4 hours 15 minutes earlier.

Area forecast discussion, Mar 27, 12:45 PM PST, 4 hours 15 minutes before

Area Forecast Discussion
National Weather Service Sacramento CA
145 PM PDT Mon Mar 27 2023

.SYNOPSIS...
Strong system arrives late today bringing moderate rain,
thunderstorm chances, gusty winds, heavy mountain snow and
significant mountain travel impacts through mid-week.

&&

.Discussion...
GOES-West visible imagery reveals a shield of mid/high clouds
streaming overhead northern California this afternoon. These
clouds are associated with the next storm system that is knocking
on our doorstep. Northern California doppler radars are detecting
light echos, but have yet to see any measurable ground reports as
the atmospheric column has yet to saturate.

Over the next 12 to 24 hours, this storm will push south/east,
bringing precipitation chances to the entire region. Coastal Range
will see snow developing around or just after sunset while the
onset of the Sierra snow will occur near midnight tonight. Appears
there will be just enough cold air trapped at the far end of the
Sacramento Valley to bring the potential measurable snow to the
Redding Metro late tonight and through sunrise Tuesday. Winter
Storm Warning is in effect for the Redding Metro as several inches
of snow are likely, particularly in the hills/ridges surrounding
the city. The airport will likely see lesser amounts. Snow levels
will rise through the day on Tuesday with snow transitioning back
to rain for the North Valley.

For the Sierra, expect heavy snow with major impacts from this
storm. Widespread moderate to heavy snow will transition to
scattered snow showers overnight Tuesday and into Wednesday.
Upwards of 2 to 4 total feet of snow are possible above 4000 feet
with the heaviest rates of 1 to 3 inches per hour occurring
Tuesday morning through Tuesday evening. Motorists would always
check with CalTrans for the latest road conditions, restrictions,
and/or closures.

Valley rain totals will range from roughly 0.5 to 2.0 inches.
Tuesday's rain will be stratiform-driven while Wednesday will be
more convective in nature with showers. Additionally, can't rule
out the chance of an afternoon thunderstorm as well on Wednesday.
Any strong showers or thunderstorms that do develop will have the
potential to bring heavy downpours and small hail. Runoff will
result in some renewed rises along area waterways through the week
as it makes its way downstream through the river systems.

Another impact with this storm will be the gusty southerly winds.
Latest forecast brings gusts of 20 to 30 mph for the northern San
Joaquin Valley, 30 to 40 mph for the Sacramento Metro, and 35 to
45 mph for the northern Sacramento Valley. Strong winds will also
impact the foothills and mountains with higher gusts possible for
the mountains.

Aside limited shower chances in the mountains, expect dry
conditions on Thursday. // Rowe

&&

.EXTENDED DISCUSSION (Friday THROUGH Monday)...
Clusters and ensembles advertise another system late week/early
weekend. Right now, it appears the best potential for
precipitation will be for the northern third or half of
California. At this point, total amounts would be lower than the
early week system. Will continue to keep a close eye as forecast
details become better understood over the coming days. // Rowe

&&

.AVIATION...
VFR conditions are forecast to prevail through roughly 00-06Z
Tuesday. MVFR/IFR ceilings will begin to develop thereafter from
north to south as a storm system begins to impact the region.
Can't rule out light snow around KRDD. Southerly surface winds
will increase after 06Z Tuesday with gusts up to 25 to 40 kt.
Higher gusts are likely in the mountains.

&

.STO WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning from 4 PM this afternoon to 10 AM PST
Wednesday for Mountains Southwestern Shasta County to Western
Colusa County-Northeast Foothills/Sacramento Valley-Shasta Lake
Area / Northern Shasta County.

Winter Storm Warning from 10 PM this evening to 7 PM PST
Wednesday for Burney Basin / Eastern Shasta County-Motherlode-
West Slope Northern Sierra Nevada-Western Plumas County/Lassen
Park.

Wind Advisory from 7 PM this evening to 4 PM PST Tuesday for
Central Sacramento Valley-Motherlode-Mountains Southwestern
Shasta County to Western Colusa County-Northeast
Foothills/Sacramento Valley-Northern Sacramento Valley-Southern
Sacramento Valley.

Winter Storm Warning from 10 PM this evening to 10 AM PST
Tuesday for Northern Sacramento Valley.

&&

The radar

The Sacramento radar (KDAX), 19 km away, was scanning. The volume nearest the first event began at 18:32 UTC.

Open the radar archive at this moment

Event by event

7 heavy snow, 5 flood, 1 funnel cloud. Local standard time, as filed.

Heavy Snow, Shasta Lake/North Shasta County

When: March 27, 5:00 PM PST to March 29, 10:00 AM PST
Where: Shasta Lake/North Shasta County forecast zone
Reported by: Other Federal Agency

The National Operational Hydrological Remote Sensing Center's gridded snowfall analysis estimated 6 to 24 inches over Shasta Lake and northern Shasta County over 72 hours. A trained spotter at Sims at an elevation of 2500 ft reported 14 inches in 24 hours. Caltrans reported the closure of Interstate 5 northbound at Fawndale for about 10 hours due to winter weather conditions.

Heavy Snow, Mountains Southwestern Shasta County to Western Colusa County

When: March 27, 5:00 PM PST to March 29, 10:00 AM PST
Where: Mountains Southwestern Shasta County to Western Colusa County forecast zone
Reported by: Other Federal Agency

The National Operational Hydrological Remote Sensing Center's gridded snowfall analysis estimated 6 to 24 inches over the mountains of southwestern Shasta County to western Colusa County over 72 hours.

Heavy Snow, Burney Basin/Eastern Shasta County

When: March 27, 10:00 PM PST to March 29, 7:00 PM PST
Where: Burney Basin/Eastern Shasta County forecast zone
Reported by: Other Federal Agency

The National Operational Hydrological Remote Sensing Center's gridded snowfall analysis estimated 4 to 18 inches over the Burney Basin and Eastern Shasta County over 72 hours.

Heavy Snow, Mt Shasta/Western Plumas County

When: March 27, 10:00 PM PST to March 29, 7:00 PM PST
Where: Mt Shasta/Western Plumas County forecast zone
Reported by: CoCoRaHS

CoCoRaHS reported storm total amounts of 36 inches in Chester at 4526 ft, 38 inches at Meadow Valley at an elevation of 4380 ft, and 28 inches at Shingletown at an elevation of 3630 ft. The National Operational Hydrological Remote Sensing Center's gridded snowfall analysis estimated 12 to 36 inches over the Lassen Park and western Plumas County area over 72 hours. Lassen National Park reported 22 inches of snow.

Heavy Snow, West Slope Northern Sierra Nevada

When: March 27, 10:00 PM PST to March 29, 7:00 PM PST
Where: West Slope Northern Sierra Nevada forecast zone
Deaths: 1 direct, 0 indirect
Reported by: Trained Spotter

Ski resorts reported storm total snow amounts of 23 inches at Kirkwood, 19 inches at Sugar Bowl, and 17 inches at Sierra at Tahoe. Caltrans District 3 reported storm total snow amounts of 23.5 inches at Kingvale, 21 inches at Soda Springs, and 18 inches at Eagle Lakes. The National Operational Hydrological Remote Sensing Center's gridded snowfall analysis estimated 6 to 30 inches over the west slope northern Sierra Nevada over 72 hours. 1 death was reported by broadcast media in Alta, CA where a man died from a collapsed snow bank, trapping him next to a generator and exposing him to carbon monoxide. Interstate 80 was closed intermittently on 3/28 due to winter weather conditions and multiple spinouts.

Heavy Snow, Northeast Foothills/Sacramento Valley

When: March 28, 7:00 AM PST to 11:00 PM PST
Where: Northeast Foothills/Sacramento Valley forecast zone
Reported by: Social Media

Reports on social media showed an estimated 2 inches of snow on the ground in Grass Valley with more snow falling. The National Operational Hydrological Remote Sensing Center's gridded snowfall analysis estimated 1 to 8 inches of storm total snow over portions of the the northeast foothills. CoCoRaHS reported 3.1 inches of snow near Nevada City at an elevation of 2390 ft, and 7 inches near Grass Valley at an elevation of 2782 ft.

Heavy Snow, Motherlode/Camptonville to Groveland

When: March 28, 10:00 AM PST to March 29, 5:00 AM PST
Where: Motherlode/Camptonville to Groveland forecast zone
Reported by: Other Federal Agency

The National Operational Hydrological Remote Sensing Center's gridded snowfall analysis estimated 1 to 4 inches over portions of the Motherlode.

Flood, Sacramento

When: March 28, 10:33 AM PST to 6:33 PM PST
Where: Sacramento County, Sacramento to 0.28 mi SW of Sacramento
Cause: Heavy Rain
Reported by: Law Enforcement
Coordinates: 38.550, -121.470

California Highway Patrol reported roadway flooding halfway into the slow lane on SR 99 near highway 50 eastbound junction due to heavy rain.

Flood, Sacramento

When: March 28, 12:46 PM PST to 8:46 PM PST
Where: Sacramento County, 2.27 mi WNW of Sacramento to 2.46 mi WNW of Sacramento
Cause: Heavy Rain
Reported by: Law Enforcement
Coordinates: 38.560, -121.510

California Highway Patrol reported roadway flooding of lanes 3 and 4 on northbound I-5 just south of Highway 50 junction.

Funnel Cloud, Shasta

When: March 28, 2:12 PM PST to 2:21 PM PST
Where: Shasta County, 0.87 mi NE of Redding Muni Arpt
Reported by: Other Federal Agency
Coordinates: 40.510, -122.290

Redding Municipal Airport ASOS reported a brief funnel cloud.

Flood, Sacramento

When: March 28, 8:45 PM PST to March 29, 8:45 PM PST
Where: Sacramento County, 1.75 mi NW of Bridge House to 2.1 mi NW of Bridge House
Cause: Heavy Rain
Reported by: Law Enforcement
Coordinates: 38.520, -121.100

California Highway Patrol reported roadway flooding on Scott Road and Latrobe Road by Indian Creek.

Flood, Solano

When: March 29, 10:38 AM PST to 8:38 PM PST
Where: Solano County, 2.14 mi SSW of Cordelia to 1.52 mi S of Cordelia
Cause: Heavy Rain
Reported by: Law Enforcement
Coordinates: 38.190, -122.140

Flooding near I-680 and Gold Hill Road offramp south of Cordelia is effecting southbound traffic on I-680.

Flood, Stanislaus

When: March 29, 3:15 PM PST to March 30, 6:15 AM PST
Where: Stanislaus County, 1.09 mi NW of West Modesto to 1.01 mi NW of West Modesto
Cause: Heavy Rain
Reported by: Law Enforcement
Coordinates: 37.663, -121.031

Mudslide on SR 99 North and 6th onramp. Onramp closed.

The people who died

As the offices recorded each death: direct deaths were caused by the weather itself, indirect ones by something it set in motion.

Event	Date	Age	Sex	Where	Kind
Heavy Snow, West Slope Northern Sierra Nevada	2023-03-29		Male	Permanent Home	Direct

What these are

Heavy Snow: Snowfall reaching the local warning threshold without the other hazards of a winter storm.
Flood: Flooding that develops more slowly than a flash flood: rivers leaving their banks, or water standing over land for an extended time.
Funnel Cloud: A rotating column of cloud extending from a thunderstorm that did not reach the ground.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

Every storm in California in 2023 Every state in 2023 This day in weather history Warnings in California, March 2023

Sources

NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 1087855, 1087856, 1087853, 1087857, 1087858, 1087861, 1087864, 1087846, 1087847, 1087851, 1087848, 1087849, 1087850.