Tornadoes · United States · Utah · 2009

EF0 tornado, Willard, Utah, May 3, 2009

This EF0 tornado ran 1.0 miles across Box Elder County on May 3, 2009, touching down at 8:50 PM MDT and reaching 15 yards wide. It killed nobody, and did $25,000 of property damage.

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.

  1. EF065 to 85 mphthis tornado

    Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.

  2. EF186 to 110 mph

    Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.

  3. 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.

  4. 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.

  5. EF4166 to 200 mph

    Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.

  6. 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.

  7. 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
May 3, 2009
Touchdown
8:50 PM MDT (02:50 UTC)
Lifted
8:55 PM MDT (02:55 UTC)
On the ground
5 minutes
Path length
1.0 miles (1.6 km)
Path width
15 yards (14 m)
Deaths
0
Injuries
0
Property damage
$25,000
County
Box Elder County
Touchdown point
41.404, -112.035
Lift-off point
41.405, -112.030
Record number
0905032050-01

What the Weather Service recorded

Thunderstorms moved across northern Utah on the afternoon of May 3rd, some of them severe. Both gusty winds and severe hail were observed, and an EF0 tornado touched down in Willard, Utah. In addition, strong gusty winds ocurred near the Great Salt Lake after the cold frontal passage.

A magnitude EF0 tornado touched down in Willard. The tornado path was one mile, starting at 75 East 300 South and ending at 300 East 230 South. The damage from the tornado included damaged siding, several uprooted trees, a couple of snapped trees, and a tossed empty snowmobile trailer.

From NOAA NCEI's Storm Events Database, the narrative the local forecast office wrote for Storm Data.

The warnings

No tornado warning for this county appears in the archive as in force at the moment the tornado touched down.

Every warning and watch covering the touchdown point that day, from the Iowa Environmental Mesonet's archive of National Weather Service products. Lead time is measured from the issue of the warning in force to the touchdown time in the database, both of which were recorded to the minute by different people.

The forecast that day

The Storm Prediction Center had this point in a General Thunderstorms Risk. The outlook in force was issued at 01:01 UTC.

SPC's Day 1 convective outlook as it stood when the tornado began, read at the touchdown point. The same archive is on the radar archive.

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.

Salt Lake City I, UT (KSLC), 00:00Z

2.8 hours before the tornado, 70 km from the path. May 4, 2009.

Skew-T log-pSkew-T log-p diagram, Salt Lake City I, UT at 00:00Z on 2009-05-04Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 318 joules per kilogram, CIN -22, lifted condensation level 1751 meters above ground. Wind barbs in knots down the right edge.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed. The warm shading is its CAPE, the cool shading the inhibition it has to break through.
HodographHodograph, Salt Lake City I, UT at 00:00Z on 2009-05-04The wind through the lowest 10 kilometers as a curve, rings every 10 meters per second labeled in knots. Zero to 1 km storm-relative helicity 25 square meters per square second, 0 to 6 km bulk shear 51 knots.1939587897117136Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km. RM and LM are the right and left moving storms Bunkers' method gives; the shaded area is the 0 to 1 km storm-relative helicity.
Mixed-layer CAPE
318 J/kg
Mixed-layer CIN
-22 J/kg
Surface CAPE
315 J/kg
Mixed-layer LCL
1751 m above ground
0-6 km bulk shear
51 kt
0-1 km bulk shear
6 kt
0-1 km storm-relative helicity
25 m²/s²
0-3 km storm-relative helicity
125 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.3
0-3 km lapse rate
9.1 K/km

Open this sounding in Storm Lab

Salt Lake City I, UT (KSLC), 12:00Z

9.2 hours after it, 70 km from the path. May 4, 2009.

Skew-T log-pSkew-T log-p diagram, Salt Lake City I, UT at 12:00Z on 2009-05-04Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 19 joules per kilogram, CIN -25, lifted condensation level 1141 meters above ground. Wind barbs in knots down the right edge.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed. The warm shading is its CAPE, the cool shading the inhibition it has to break through.
HodographHodograph, Salt Lake City I, UT at 12:00Z on 2009-05-04The wind through the lowest 10 kilometers as a curve, rings every 10 meters per second labeled in knots. Zero to 1 km storm-relative helicity -11 square meters per square second, 0 to 6 km bulk shear 52 knots.1939587897117Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km. RM and LM are the right and left moving storms Bunkers' method gives; the shaded area is the 0 to 1 km storm-relative helicity.
Mixed-layer CAPE
19 J/kg
Mixed-layer CIN
-25 J/kg
Surface CAPE
174 J/kg
Mixed-layer LCL
1141 m above ground
0-6 km bulk shear
52 kt
0-1 km bulk shear
6 kt
0-1 km storm-relative helicity
-11 m²/s²
0-3 km storm-relative helicity
78 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
6.5 K/km

Open this sounding in Storm Lab

The radar

The Salt Lake City radar (KMTX), 38 km away, was scanning. The volume nearest the touchdown began at 02:50 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.

What was reported nearby

Local storm reports within 60 km of the path, in the three hours either side.

Time (UTC)ReportWhereCountyRemark
01:30 UTCNON-TSTM WND GST 62Promontory PtBox Elder, UTHAT ISLAND - 4242 FT
01:30 UTCNON-TSTM WND GST 71SalineBox Elder, UTPROMONTORY POINT - 6926 FT
01:46 UTCTSTM WND DMGWillardBox Elder, UTTREE BLOWN DOWN ON CAR IN DRIVEWAY.
01:50 UTCNON-TSTM WND GST 66WellsvilleCache, UTSHERWOOD HILLS - 5039 FT
01:50 UTCTORNADOWillardBox Elder, UTA MAGNITUDE EF0 TORNADO TOUCHED DOWN IN WILLARD. THE TORNADO PATH WAS ONE MILE...STARTING AT 75 EAST 300 SOUTH...AND ENDING AT 300 EAST 230 SOUTH. THE DAMAGE FROM THE TORNADO INCLUDED SIDING...SEVERAL TREES UPROOTED...A
01:55 UTCHAIL 0.75PerryBox Elder, UTHAIL ACCUMULATION 2 INCHES DEEP.
02:09 UTCHAIL 0.25LibertyWeber, UT
02:09 UTCHAIL 0.25SyracuseDavis, UT
02:10 UTCNON-TSTM WND GST 60UintahWeber, UTWEBER CANYON POWER PLANT - 5801 FT
02:20 UTCHAIL 0.25Brigham CityBox Elder, UTHAIL ACCUMULATED 1/2 INCH DEEP.
02:25 UTCHAIL 0.25OgdenWeber, UT
02:33 UTCHAIL 0.25UintahWeber, UT

From the Iowa Environmental Mesonet's archive of National Weather Service local storm reports.

This ground now

The live radar over the trackEvery 2009 tornado in UtahEvery tornado in Utah since 1950Warnings in force in Utah nowThe forecast where you are

The other tornadoes of May 3, 2009

21 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
May 36:44 AM CDTEF1Trinity, TX2.150$60,000
May 37:00 AM CDTEF0Leake, MS4.3100$8,000
May 37:38 AM CDTEF0Bienville Parish, LA1.850
May 38:03 AM CDTEF0Bienville Parish, LA1.150
May 38:40 AM CDTEF2Winn Parish, LA1.53992$3.0 million
May 38:51 AM CDTEF0Catahoula Parish, LA3.040$1,000
May 39:55 AM CDTEF1Claiborne, MS4.650$15,000
May 311:07 AM CDTEF1Jefferson Davis, MS8.4400$262,000
May 311:12 AM CDTEF1Covington, MS20.1400$145,000
May 311:30 AM CDTEF1Smith, MS4.8350$328,000
May 311:41 AM CDTEF1Jasper, MS0.6176$10,000
May 31:32 PM CDTEF1Hale, AL0.150$75,000
May 31:54 PM CDTEF0Shelby, AL2.6200$120,000
May 32:03 PM CDTEF1Shelby, AL1.4300$10,000
May 32:15 PM CDTEF1St. Clair, AL0.9100$60,000
May 32:27 PM CDTEF1St. Clair, AL16.6800$100,000
May 33:40 PM CDTEF1Marshall, AL0.350$20,000
May 35:22 PM CDTEF1Cumberland, TN3.2300$125,000
May 36:00 PM CDTEF1Madison, AL1.675$30,000
May 37:02 PM EDTEF0Floyd, VA0.760$10,000
May 38:38 PM EDTEF0Rockingham, NC1.320$100,000

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.