Tornadoes · United States · Kentucky · 2021

EF1 tornado, Shelby City to Clifton, Kentucky, December 11, 2021

From Shelby City to Clifton, this EF1 tornado ran 3.6 miles across Boyle County on December 11, 2021, touching down at 4:02 AM EST and reaching 400 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.

  1. EF065 to 85 mph

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

  2. EF186 to 110 mphthis tornado

    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
EF1
Date
December 11, 2021
Touchdown
4:02 AM EST (09:02 UTC)
Lifted
4:05 AM EST (09:05 UTC)
On the ground
3 minutes
Path length
3.6 miles (5.8 km)
Path width
400 yards (366 m)
Deaths
0
Injuries
0
County
Boyle County
Touchdown point
37.646, -84.791
Lift-off point
37.675, -84.738
Record number
2112110302-01

The damage survey

82 damage points were recorded along this path by NWS LMK, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF2. The highest wind the damage implies is 135 mph.

  • 1/2 of large outbuilding destroyed and blown away debris extending 1 mile to the north east
  • Carport blown one home north north east
  • Home/barn combo - roof blown off
  • Hit by debris from barn to nw

Survey points are preliminary and are the raw material the published rating was built from. Source: NWS Damage Assessment Toolkit.

What the Weather Service recorded

Strong southern winds brought warm temperatures and plenty of moisture into an environment of strong wind shear ahead of an advancing cold front. This resulted in unusually warm temperatures for a December day and the ingredients to produce a historic tornado outbreak and flash flooding. This included multiple long track tornadoes. Central Kentucky saw 18 tornadoes that injured 96 and killed 18. An additional death occurred in a flash flood.

The tornado began near Danville-Boyle County Airport along Simpson Lane in Junction City. Roof damage occurred in this neighborhood, and then the tornado continued toward the airport. Three hangar buildings were destroyed and several aircraft were mangled and heavily damaged. The tornado then crossed Airport Road to the northeast where a home had the roof completely destroyed and a nearby barn was severely damaged. After this point northeast of the airport the tornado did not produce noticeable damage in nearby farm fields.

The tornado began near Morning Pointe of Danville along Perryville Road just south of Millennium Park, where significant roof damage occurred to a church and a gas station. Several trees were also uprooted and snapped at this location. The tornado continued through neighborhoods along West Lexington Avenue where tree and roof damage occurred. The tornado continued to produce tree and roof damage to homes between Caldwell Manor and Bellvue Cemetery before crossing Highway 2168. The tornado continued near Waterworks Road with destruction of a barn and roof damage to a residence nearby,. No damage was observed beyond Waterworks Road.

This tornado formed approximately 2.9 miles east northeast of Danville Goodall Airport near Chrisman Lane and tracked northeast for approximately 5.2 miles before crossing into western Garrard County. The tornado continued approximately 1.9 miles into Garrard County before dissipating at 0411 EST. In Boyle County, The tornado began on the northeast side of Highway 150 near the Boyle/Lincoln County line where a barn outbuilding had severe roof damage. The tornado continued to the northeast along Chrisman Lane where barns had roof uplift damage. After the tornado moved past Cooks Loop, damage continued on the other side of Chrisman Lane where a barn received roof damage. There was extensive tree damage, with trees being uprooted or snapped along Chrisman Lane near Chrisman Circle. The tornado then continued along mostly rural portions near the Boyle and Lincoln County Lines. To the east northeast of Hedgeville, several barns and homes in this area had major roof damage along Lancaster Road. The tornado continued with tree damage along Rankin Road before crossing into Garrard County.

This tornado formed approximately 2 miles north of Clifton near Kings Ridge Road and tracked northeast for approximately 0.9 miles before crossing into northern Garrard County. The tornado continued approximately 2.1 miles into Garrard County before dissipating at 0411 EST. In Boyle County, The tornado began near the Old Bridge Golf Club where trees were uprooted and branches were broken. Then, the tornado crossed Herrington Lake into Garrard County.

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

The warnings

3 minutes of warning. NWS LMK issued a tornado warning for this county at 08:59 UTC, 3 minutes before the tornado touched down, in force until 09:23 UTC.

The county was under a tornado watch, issued at 07:29 UTC and running to 11:40 UTC.

Issued (UTC)ExpiredProductOffice
07:29 UTC11:40 UTCTornado WatchLMK
08:22 UTC09:00 UTCTornado WarningLMK
08:59 UTC09:23 UTCTornado WarningLMK
09:43 UTC13:45 UTCFlood AdvisoryLMK
10:58 UTC11:30 UTCSevere Thunderstorm WarningLMK
10:58 UTC11:30 UTCSevere Thunderstorm WarningLMK

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 Slight Risk, with a 0.05 chance of a tornado within 25 miles. The outlook in force was issued at 05:48 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.

Cncnati-Daytn, OH (KILN), 00:00Z

9.0 hours before the tornado, 214 km from the path. December 11, 2021.

Skew-T log-pSkew-T log-p diagram, Cncnati-Daytn, OH at 00:00Z on 2021-12-11Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 0 joules per kilogram, CIN -63174, lifted condensation level 519 meters above ground. Wind barbs in knots down the right edge.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°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, Cncnati-Daytn, OH at 00:00Z on 2021-12-11The 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 325 square meters per square second, 0 to 6 km bulk shear 71 knots.1939587897Sfc1 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
0 J/kg
Mixed-layer CIN
-63174 J/kg
Surface CAPE
0 J/kg
Mixed-layer LCL
519 m above ground
0-6 km bulk shear
71 kt
0-1 km bulk shear
28 kt
0-1 km storm-relative helicity
325 m²/s²
0-3 km storm-relative helicity
431 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
3.7 K/km

Open this sounding in Storm Lab

Cncnati-Daytn, OH (KILN), 12:00Z

3.0 hours after it, 214 km from the path. December 11, 2021.

Skew-T log-pSkew-T log-p diagram, Cncnati-Daytn, OH at 12:00Z on 2021-12-11Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 7 joules per kilogram, CIN -56, lifted condensation level 761 meters above ground. Wind barbs in knots down the right edge.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°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, Cncnati-Daytn, OH at 12:00Z on 2021-12-11The 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 205 square meters per square second, 0 to 6 km bulk shear 70 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
7 J/kg
Mixed-layer CIN
-56 J/kg
Surface CAPE
22 J/kg
Mixed-layer LCL
761 m above ground
0-6 km bulk shear
70 kt
0-1 km bulk shear
36 kt
0-1 km storm-relative helicity
205 m²/s²
0-3 km storm-relative helicity
205 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
5.7 K/km

Open this sounding in Storm Lab

The surface observations

Danville (DVK), 9 km from the path, in the two hours either side.

Time (UTC)Temp (°F)Dew point (°F)WindGust (kt)Pressure (mb)Weather
07:15 UTC64.460.8210° 17 kt231005.8
07:35 UTC66.260.8210° 17 kt261005.4
07:55 UTC66.260.8210° 17 kt271005.1
08:15 UTC6860.8200° 15 kt261004.4
08:35 UTC6860.8210° 13 kt271004.1
08:55 UTC6860.8190° 19 kt281002.4

From the Iowa Environmental Mesonet's archive of airport observations.

The radar

The Louisville radar (KLVX), 109 km away, was scanning. The volume nearest the touchdown began at 08:59 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
08:22 UTCTORNADO2 Nnw HobsonTaylor, KYEMERGENCY MANAGER REPORT OF COLLAPSED STRUCTURE WITH PEOPLE TRAPPED ON FEATHER CREEK RD NORTH OF CAMPBELLSVILLE IN NORTHERN TAYLOR COUNTY.
08:27 UTCTORNADO3 S New MarketMarion, KY*** 1 INJ *** AN NWS STORM SURVEY DETERMINED AN EF-3 TORNADO WITH PEAK WINDS OF 145MPH AND A PATH WIDTH OF A QUARTER MILE IMPACTED PORTIONS OF TAYLOR AND MARION COUNTIES EARLY SATURDAY MORNING. THE TORNADO TOUCHED DOWN A
08:41 UTCTORNADO3 Ne BradfordsvilleMarion, KYAN EF-1 TORNADO TOUCHED DOWN 3 MILES NORTHEAST OF BRADFORDSVILLE, KY, WITH 100MPH WINDS AND A PATH WIDTH OF 50 YARDS. THE TORNADO WAS ON THE GROUND FOR APPROXIMATELY 1.9 MILES BEFORE LIFTING 3 MILES SOUTHWEST OF GRAVEL S
09:01 UTCTORNADO1 Ese Junction CityBoyle, KYAN EF-2 TORNADO OCCURRED 1 MILE ESE OF JUNCTION CITY, KY NEAR THE BOYLE COUNTY AIRPORT. THE TORNADO HAD A MAX PATH WIDTH OF 100 YARDS AND A LENGTH OF 0.63 MILES. THE MAX WIND SPEEDS 135 MPH, AND THE TORNADO LIFTED 4 MILE
09:02 UTCTSTM WND DMG4 S DanvilleBoyle, KYBOYLE COUNTY AIRPORT HAD 3 HANGERS TOTALLY DESTROYED WITH 25 AIRCRAFT DAMAGED. TIME ESTIMATED BASED ON RADAR.
09:02 UTCTORNADO1 Wnw DanvilleBoyle, KYAN EF-1 TORNADO OCCURRED 1 MILE WNW OF DANVILLE, KY WITH 110 MPH WINDS AND A MAX PATH WIDTH OF 400 YARDS. THE TORNADO PATH WAS 3.63 MILES LONG BEFORE LIFTING 3 MILES NE OF DANVILLE, KY. PLEASE SEE ASSOCIATED PNS FOR MORE
09:04 UTCTORNADO4 Se DanvilleBoyle, KYADDITIONAL DAMAGE WAS RELAYED TO THE NWS AND THIS REPORT CORRECTS 2 PREVIOUS BOYLE COUNTY TORNADO TRACKS INTO ONE TRACK FROM DECEMBER 11TH. THE NWS STORM SURVEY DETERMINED THE TORNADO HAD PEAK WINDS OF 110 MPH WITH A MAX
09:04 UTCTORNADO4 Se DanvilleBoyle, KYAN EF-1 TORNADO OCCURRED 4 MILES SE OF DANVILLE, KY. THE TORNADO HAD A MAX PATH WIDTH OF 50 YARDS WITH A PATH LENGTH OF 0.61 MILES. THE MAX WIND SPEEDS WERE 93 MPH, AND THE TORNADO LIFTED SHORTLY AFTER TOUCHDOWN ABOUT 4
09:08 UTCTORNADO3 Sw BryantsvilleBoyle, KYAN EF-1 TORNADO OCCURRED 3 MILES SW OF BRYANTSVILLE, KY OR 5 MILES ENE OF DANVILLE, KY. THE TORNADO HAD A MAX PATH WIDTH OF 950 YARDS AND A LENGTH OF 2.93 MILES. THE MAX WIND SPEEDS WERE 94 MPH, AND THE TORNADO LIFTED 1
09:09 UTCTORNADO3 Sw BryantsvilleGarrard, KYAN EF-1 TORNADO OCCURRED 3 MILES SW OF BRYANTSVILLE, KY OR 5 MILES ENE OF DANVILLE, KY. THE TORNADO HAD A MAX PATH WIDTH OF 950 YARDS AND A LENGTH OF 2.93 MILES. THE MAX WIND SPEEDS WERE 94 MPH, AND THE TORNADO LIFTED 1
09:09 UTCTORNADO5 E DanvilleBoyle, KYAN EF-1 TORNADO OCCURRED 5 MILES EAST OF DANVILLE, KY NEAR HEDGEVILLE, KY. THE TORNADO HAD A MAX PATH WIDTH OF 600 YARDS WITH A PATH LENGTH OF 1.93 MILES. THE MAX WIND SPEED WAS 110 MPH, AND THE TORNADO LIFTED 5 MILES WN
09:09 UTCTORNADO5 E DanvilleGarrard, KYAN EF-1 TORNADO OCCURRED 5 MILES EAST OF DANVILLE, KY NEAR HEDGEVILLE, KY. THE TORNADO HAD A MAX PATH WIDTH OF 600 YARDS WITH A PATH LENGTH OF 1.93 MILES. THE MAX WIND SPEED WAS 110 MPH, AND THE TORNADO LIFTED 5 MILES WN
09:10 UTCTSTM WND DMG4 Sse BryantsvilleGarrard, KYAN EF-1 TORNADO FORMED ALONG A DISTINCT LINE BREAK SEEN ON WSR-88D. THE NWS DRONE FOUND THE TORNADO TOUCH DOWN JUST SOUTHWEST OF 517 RICH WAY AT BLUEGRASS DIESEL PERFORMANCE AUTO BODY SHOP. THE EF-1 90 MPH TORNADO DID MA
09:10 UTCTORNADO3 Sse BryantsvilleGarrard, KYCORRECTS PREVIOUS TSTM WND DMG REPORT FROM 3 SSE BRYANTSVILLE. AN EF-1 TORNADO FORMED ALONG A DISTINCT LINE BREAK SEEN ON WSR-88D. THE NWS DRONE FOUND THE TORNADO TOUCH DOWN JUST SOUTHWEST OF 517 RICH WAY AT BLUEGRASS DI
09:11 UTCTSTM WND DMGMidwayWoodford, KYTREES DOWN IN MIDWAY.
09:11 UTCTORNADO5 E DanvilleGarrard, KYCORRECTS PREVIOUS TORNADO REPORT FROM 5 E DANVILLE. AN EF-1 TORNADO OCCURRED 5 MILES EAST OF DANVILLE, KY NEAR HEDGEVILLE, KY. THE TORNADO HAD A MAX PATH WIDTH OF 600 YARDS WITH A PATH LENGTH OF 1.93 MILES. THE MAX WIND
09:11 UTCTORNADO5 Wnw LancasterGarrard, KYCORRECTS PREVIOUS TORNADO REPORT FROM 5 E DANVILLE. AN EF-1 TORNADO OCCURRED 5 MILES EAST OF DANVILLE, KY NEAR HEDGEVILLE, KY. THE TORNADO HAD A MAX PATH WIDTH OF 600 YARDS WITH A PATH LENGTH OF 1.93 MILES. THE MAX WIND
09:22 UTCTORNADO1 N KirksvilleMadison, KYTHE EF-1 TORNADO TOUCHED DOWN JUST WEST OF HIGHWAY 595 NORTHWEST OF THE KIRKSVILLE COMMUNITY IN WESTERN MADISON COUNTY. THERE WERE SOME TWISTED TREES IN A FOREST GROVE. THE TORNADO THEN HIT AN OLD FARMHOUSE AS WELL AS A
09:30 UTCTSTM WND DMG1 Nw RichmondMadison, KYTREE DAMAGE, TIME ESTIMATED BY RADAR.
09:30 UTCTSTM WND DMG3 W RedhouseMadison, KYDOWNED TREE BLOCKING ROADWAY NEAR EXIT 95 ON I-75.
09:30 UTCTSTM WND DMG4 W RedhouseMadison, KYDOWNED POWER LINES AND NUMEROUS PEOPLE WITHOUT POWER. TIME ESTIMATED BY RADAR.
09:31 UTCTORNADO3 W RedhouseMadison, KYTHE TORNADO TOUCHED DOWN JUST SOUTHWEST OF THE INTERSECTION OF CLAY LANE AND LEXINGTON ROAD. THERE WAS ROOF AND GUTTER DAMAGE TO 214 CLAY LN ALONG WITH ONE UPROOTED TREE. SEVERAL SOFT PINES AND CEDAR TREES WERE TWISTED A
09:34 UTCTSTM WND DMGSalomaTaylor, KYREPORT FROM MPING: HOMES/BUILDINGS COMPLETELY DESTROYED.
10:03 UTCTSTM WND DMGStanfordLincoln, KYTREES AND POWERLINES DOWN NEAR STANFORD AND WESTERN PORTIONS OF COUNTY.
10:13 UTCTSTM WND DMG3 Ese MccrearyGarrard, KYMULTIPLE TREES AND POWERLINES DOWN.
10:17 UTCTSTM WND DMG3 Ne RichmondMadison, KYTREES DOWN BLOCKING ROADWAY.
10:57 UTCTSTM WND DMGHarrodsburgMercer, KYPOWERLINES DOWN ACROSS PORTIONS OF THE COUNTY. TIME ESTIMATED FROM RADAR.
11:05 UTCTSTM WND DMG3 Se HoguePulaski, KYTREE DOWNED ALONG WITH POWER LINES BLOCKING BOTH LANES OF HIGHWAY 1674. TIME ESTIMATED OFF RADAR.
11:20 UTCTSTM WND DMG4 Ssw YosemiteCasey, KYTREES DOWN CHESTNUT HILL ROAD AND POPLAR LEVEL ROAD. TIME ESTIMATED FROM RADAR.
11:32 UTCTSTM WND DMGCrab OrchardLincoln, KYTREES DOWN.
11:40 UTCTSTM WND GST 56DabneyPulaski, KYRECORDED AT THE PULASKI COUNTY KY MESONET STATION.
11:44 UTCTSTM WND DMG1 N BrodheadRockcastle, KYA TREE WAS BLOWN DOWN ALONG POSSUM KINGDOM ROAD IN THE BRODHEAD COMMUNITY. THE EVENT TIME IS ESTIMATED FROM RADAR.
11:48 UTCTSTM WND DMGRockfordRockcastle, KYTWO TREES WERE BLOWN DOWN ON SCAFFOLD CANE ROAD NEAR THE MADISON COUNTY LINE. THE EVENT TIME IS ESTIMATED FROM RADAR.

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

This ground now

The live radar over the trackEvery 2021 tornado in KentuckyEvery tornado in Kentucky since 1950Warnings in force in Kentucky nowThe forecast where you are

The other tornadoes of December 11, 2021

37 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
December 111:06 AM ESTEF1Hardin, KY1.950
December 1112:40 AM CSTEF0Fayette, TN0.550
December 1112:47 AM CSTEF3Logan, KY28.01,4001
December 111:51 AM ESTEF1Spencer, KY1.9100
December 111:09 AM CSTEF3Bowling Green tornado, KY29.34401663
December 111:19 AM CSTEF2Warren, KY6.1300
December 111:32 AM CSTEF1Madison, TN7.9300$700,000
December 111:38 AM CSTEF2Barren, KY17.0900
December 111:40 AM CSTEF2Henderson, TN15.36001$4.0 million
December 111:52 AM CSTEF2Hart, KY23.85281
December 112:00 AM CSTEF1Decatur, TN9.1100$220,000
December 113:06 AM ESTEF1Hardin, OH1.6150$300,000
December 112:15 AM CSTEF2Perry, TN15.2600$140,000
December 113:20 AM ESTEF3Taylor, KY14.5450131
December 112:32 AM CSTEF1Hickman, TN8.5400$50,000
December 112:40 AM CSTEF2Hickman, TN10.95002$2.0 million
December 113:41 AM ESTEF1Marion, KY1.950
December 112:49 AM CSTEF0Dickson, TN5.4175$10,000
December 112:57 AM CSTEF2Dickson, TN12.64001$1.5 million
December 114:01 AM ESTEF2Boyle, KY0.6100
December 114:04 AM ESTEF1Boyle, KY7.1100
December 114:07 AM ESTEF1Garrard, KY3.0950
December 114:10 AM ESTEF1Garrard, KY0.6100
December 113:12 AM CSTEF0Davidson, TN9.0300$250,000
December 114:22 AM ESTEF1Madison, KY0.375
December 113:30 AM CSTEF1Davidson, TN6.8150$1.8 million
December 114:31 AM ESTEF1Madison, KY1.2125
December 113:31 AM CSTEF1Davidson, TN7.71001$1.3 million
December 113:33 AM CSTEF0Davidson, TN1.450$250,000
December 113:42 AM CSTEF0Sumner, TN6.250$25,000
December 113:48 AM CSTEF0Wilson, TN3.150$20,000
December 114:04 AM CSTEF0Smith, TN7.375$20,000
December 114:20 AM CSTEF1Monroe, TN to KY11.275$500,000
December 114:30 AM CSTEF1Prentiss, MS4.5100$125,000
December 116:17 AM CSTEF0Giles, TN5.050$20,000
December 117:39 AM CSTEF0Grundy, TN8.9100$50,000
December 115:16 PM ESTEF0Wilkinson, GA3.8200

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.