Tornadoes · United States · California · 2021
EF0 tornado, Vina, California, January 4, 2021
This EF0 tornado ran 2.7 miles across Tehama County on January 4, 2021, touching down at 2:40 PM PST and reaching 3 yards wide. It killed nobody.
The rating scale
Tracks are drawn in the color of the rating. The Enhanced Fujita scale rates the damage rather than measuring the wind: the speeds are what that damage is taken to imply.
EF065 to 85 mphthis tornado
Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.
EF186 to 110 mph
Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.
EF2111 to 135 mph
Considerable damage. Roofs torn off well-built houses, frame homes shifted on their foundations, mobile homes destroyed, large trees snapped or uprooted, cars lifted off the ground.
EF3136 to 165 mph
Severe damage. Whole stories of well-built houses destroyed, large buildings badly damaged, trains overturned, trees debarked, heavy cars lifted and thrown.
EF4166 to 200 mph
Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.
EF5over 200 mph
Incredible damage. Strong frame houses swept off their foundations, car-sized missiles thrown more than 100 meters, steel-reinforced concrete badly damaged, high-rise buildings deformed.
Unrated
The survey recorded a tornado but could not put a number on it, most often because it crossed open country and damaged nothing a rating can be read from.
The record
- Rating
- EF0
- Date
- January 4, 2021
- Touchdown
- 2:40 PM PST (22:40 UTC)
- Lifted
- 2:50 PM PST (22:50 UTC)
- On the ground
- 10 minutes
- Path length
- 2.7 miles (4.3 km)
- Path width
- 3 yards (3 m)
- Deaths
- 0
- Injuries
- 0
- County
- Tehama County
- Touchdown point
- 39.956, -122.017
- Lift-off point
- 39.975, -121.973
- Record number
- 2101041640-01
What the Weather Service recorded
A trough from the Gulf of Alaska brought Valley rain, mountain snow, and thunderstorms to northern California. The system hit in two waves, the initial frontal passage followed the trough axis moving over northern California. Clearing behind the cold front allowed for a favorable thunderstorm environment to develop, which would eventually lead to two confirmed tornadoes for interior northern California. Snow levels with this system started around 5,000 and 6,500 feet and dropped down to 4,000 and 4,500 feet.
A tornado was sited on the ground out in an open field near Vina by Calfire. No damage has been reported. Multiple photos and videos confirm a tornado in clear contact with the ground. Tornado track, width, and duration estimated by radar and reports.
From NOAA NCEI's Storm Events Database, the narrative the local forecast office wrote for Storm Data.
What forecasters said that day
The local office's own words before the tornado touched down, 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 tornado touched down at Jan 4, 2:54 AM PST, 11 hours 46 minutes earlier.
Area forecast discussion, Jan 4, 2:54 AM PST, 11 hours 46 minutes before
Area Forecast Discussion National Weather Service Sacramento CA 254 AM PST Mon Jan 4 2021 .SYNOPSIS... Strong Pacific Storm will bring periods of heavy rain, possible thunderstorms, heavy mountain snow and blustery winds to Norcal today. Tuesday and most of Wednesday will be dry, but additional rain and snow is possible again later in the week. && .DISCUSSION... Moderate TPW moisture plume (AR) will be moving inland with a favorable SW trajectory and orographic effects for heavy precip mainly N of the I-80 corridor, and especially for the Feather/Yuba River basins. Upper trof nearing 130W at 09z will be nearing the N Coast by 18z and moving inland thru 00z. Surface cold front and strong LLJ will precede the trof mainly moving across our CWA from 18z-00z with the tail end of the front hanging back over the Sierra into the evening. The HREF Probability of >40 dBZ REF shows a 100% bulls-eye over/around the North Complex burn scar from 10am-2pm, then a 70%+ from 2pm-4pm. The Probability of 1 hr rainfall >0.50" is also >70% from 11am-1pm, and given these probabilities and forecast QPF of 1.50" to 3.50" over the burn scar today, and the convective potential for the Valley and Sierra Foothills given negative LI's and several hundred J/kg of CAPE, there is the potential for lines of thunderstorms and flooding/flash flooding over that burn scar. Model QPF has generally increased slightly from yesterday with amounts mostly ranging from up to an inch in the Northern Sacramento Valley to 2 to 5 tenths of an inch southward into the San Joaquin Valley and 1 to 2.5 inches in the foothills and mountains with 3+ inches in the aforementioned Feather/Yuba River basins. Snow totals up to a foot to a foot and a half with localized amounts up to 2 feet are forecast over the higher elevations/higher peaks. Light snow will be possible down to 5000 feet this evening, especially in convective showers. The WAD (wind advisory) for mainly the Valley and coastal mtns looks on track given the nearly 50Kts NAM 925 winds ahead/along the front from 15z-21z. the strongest winds are expected to the in the Nrn half of the Sac Vly. The WSW for the mountains also looks on track with periods of heavy snow with 1-2 inch hourly rates possible given the instability forecast over the Sierra during the afternoon, mainly from 21z-after 00z (1pm-5pm or so). Ridging will follow this trof as it moves across the Nrn Plains/Nrn Rockys on Tue, followed by a another trof mainly moving into the Pac NW, but also brushing Norcal, late Wed and Wed night. This is a weaker TPW plume (AR) with much lighter QPF expected in Norcal, e.g. a couple of inches of snow for the Sierra, compared with a foot to a foot and a half with today's system. Another system is forecast to move into our area late Thu/thu nite. JHM .EXTENDED DISCUSSION (Friday THROUGH Monday)... Pacific frontal system moves through interior NorCal Friday bringing widespread rain and mountain snow. Snow levels look to range from 3500 to 5000 feet and thus could impact mountain travel. Drier weather expected over the weekend under upper ridging. Potential for some night and morning valley fog development under moist stable conditions. Models suggest another system moving through on Monday with some uncertainty in timing and strength. && .AVIATION... Wdsprd MVFR with areas of IFR and lcl LIFR tda in intr NorCal as Pac fntl sys movs thru. Sn lvls 040-060. Isold tstm poss btwn 20z-02z in Sac Vly and ern fthls. Areas Sly sfc wnd 25g35kts in Cntrl Vly btwn 16z-23z tda. SWly sfc wnd gsts up to 50 kts poss ovr hyr mtn trrn tda. Conds impvg tngt, but areas MVFR/IFR/LIFR poss in Vly BR/FG Tue mrng. && .STO WATCHES/WARNINGS/ADVISORIES... Flash Flood Watch from 10 AM PST this morning through this evening for Northeast Foothills/Sacramento Valley-Western Plumas County/Lassen Park. Winter Storm Warning until 4 AM PST Tuesday for West Slope Northern Sierra Nevada-Western Plumas County/Lassen Park. Wind Advisory from 6 AM this morning to 8 PM PST this evening for Central Sacramento Valley-Mountains Southwestern Shasta County to Western Colusa County-Northeast Foothills/Sacramento Valley-Northern Sacramento Valley-Southern Sacramento Valley- Western Plumas County/Lassen Park. &&
In the hours before
Special weather statement, Jan 4, 1:30 PM PST, 1 hour 10 minutes before
Special Weather Statement National Weather Service Sacramento CA 130 PM PST Mon Jan 4 2021 CAZ015-016-066-042215- Northeast Foothills/Sacramento Valley-Northern Sacramento Valley-Central Sacramento Valley- 130 PM PST Mon Jan 4 2021 ...A STRONG THUNDERSTORM WILL AFFECT CENTRAL TEHAMA...WEST CENTRAL BUTTE AND NORTHERN GLENN COUNTIES... At 128 PM PST, a strong thunderstorm was located from near Red Bluff south to near Black Butte Summit, moving northeast at 30 mph. Winds in excess of 30 mph and pea size hail are possible with this storm along with heavy rain. Locations impacted include... Red Bluff, Corning, Tehama, Henleyville, Gerber-Las Flores, Richfield, Vina, Los Molinos, Black Butte Dam, Black Butte Summit and Black Butte Lake. Torrential rainfall is also occurring with this storm, and may cause localized flooding. Do not drive your vehicle through flooded roadways. LAT...LON 3977 12240 4020 12235 4035 12185 3985 12186 TIME...MOT...LOC 2128Z 245DEG 25KT 3996 12228 CM
Special weather statement, Jan 4, 1:34 PM PST, 1 hour 6 minutes before
Special Weather Statement National Weather Service Sacramento CA 134 PM PST Mon Jan 4 2021 CAZ013>015-066-068-042215- Northeast Foothills/Sacramento Valley-Northern Sacramento Valley-Burney Basin / Eastern Shasta County-Western Plumas County/Lassen Park-Shasta Lake Area / Northern Shasta County- 134 PM PST Mon Jan 4 2021 ...A STRONG THUNDERSTORM WILL AFFECT NORTH CENTRAL TEHAMA AND SOUTHEASTERN SHASTA COUNTIES... At 132 PM PST, a strong thunderstorm was located near Anderson north to near Montgomery Creek, moving northeast at 25 mph. Pea size hail and gusty winds are possible with this storm along with heavy rain. Locations impacted include... Redding, Palo Cedro, Shingletown, Anderson, Whitmore, Inwood, Round Mountain, Millville, Montgomery Creek and Cottonwood. Torrential rainfall is also occurring with this storm, and may cause localized flooding. Do not drive your vehicle through flooded roadways. LAT...LON 4030 12203 4031 12248 4084 12209 4082 12161 TIME...MOT...LOC 2132Z 237DEG 22KT 4053 12223 CM
Special weather statement, Jan 4, 2:28 PM PST, 12 minutes before
<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>Service Notice</title>
<link rel="stylesheet" href="index.css">
</head>
<body>
<main class="wrap">
<section class="card" role="status" aria-live="polite">
<div class="status" id="status">Temporary Notice</div>
<h1 id="headline">This service is currently unavailable.</h1>
<p id="message1">
The site you requested is temporarily down for maintenance or an unexpected outage.
</p>
<p id="message2">
Please try again in a few minutes.
</p>
<p class="small" id="detail">
If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
</p>
</section>
</main>
<script src="index.js"></script>
</body>
</html>The air that afternoon
The radiosonde launches on either side of the tornado, from the nearest station that was launching then, drawn and analyzed the way Storm Lab does: the same diagram, the same parcel and shear definitions SPC's mesoanalysis uses.
Oakland, CA (KOAK), 12:00Z
10.7 hours before the tornado, 249 km from the path. January 4, 2021.
- Mixed-layer CAPE
- 0 J/kg
- Mixed-layer CIN
- -2481 J/kg
- Surface CAPE
- 0 J/kg
- Mixed-layer LCL
- 890 m above ground
- 0-6 km bulk shear
- 60 kt
- 0-1 km bulk shear
- 22 kt
- 0-1 km storm-relative helicity
- 182 m²/s²
- 0-3 km storm-relative helicity
- 243 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
- 0-3 km lapse rate
- 3.3 K/km
The surface observations
Chico Municipal (CIC), 22 km from the path, in the two hours either side.
| Time (UTC) | Temp (°F) | Dew point (°F) | Wind | Gust (kt) | Pressure (mb) | Weather |
|---|---|---|---|---|---|---|
| 00:00 UTC |
From the Iowa Environmental Mesonet's archive of airport observations.
The radar
The Beale AFB radar (KBBX), 61 km away, was scanning. The volume nearest the touchdown began at 22:39 UTC.
Open the radar archive at this moment, over the track
Reflectivity and velocity, decoded from the Level II archive in the browser. Volumes take a few seconds to open the first time.
This ground now
The live radar over the trackEvery 2021 tornado in CaliforniaEvery tornado in California since 1950Warnings in force in California nowThe forecast where you are
The other tornadoes of January 4, 2021
1 more were confirmed in the United States that day.
| Date | Time | Rating | Where | Path (mi) | Width (yd) | Deaths | Injuries | Damage |
|---|---|---|---|---|---|---|---|---|
| January 4 | 1:34 PM PST | EF0 | Tehama, CA | 0.8 | 3 |
What this means
Ratings are the survey's, read off the damage rather than measured; the rating scale is above. Tornado counts rise through the record as reporting improved, so a year in the 1950s is not comparable with one today except for the strongest tornadoes, which were always noticed.
Sources
NOAA Storm Prediction Center tornado database, 1950-2025, the official record kept by NOAA's Storm Prediction Center.