Tornadoes · United States · Colorado · 2001

F0 tornado, Bennett, Colorado, July 26, 2001

This F0 tornado ran 0.1 miles across Adams County on July 26, 2001, touching down at 2:15 PM MDT and reaching 50 yards wide. It killed nobody.

The rating scale

Tracks are drawn in the color of the rating. The Fujita scale rates the damage rather than measuring the wind: the speeds are what that damage is taken to imply.

  1. F040 to 72 mphthis tornado

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

  2. F173 to 112 mph

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

  3. F2113 to 157 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. F3158 to 206 mph

    Severe damage. Whole stories of well-built houses destroyed, large buildings badly damaged, trains overturned, trees debarked, heavy cars lifted and thrown.

  5. F4207 to 260 mph

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

  6. F5261 to 318 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
F0
Date
July 26, 2001
Touchdown
2:15 PM MDT (20:15 UTC)
Path length
0.1 miles (0.2 km)
Path width
50 yards (46 m)
Deaths
0
Injuries
0
County
Adams County
Touchdown point
39.750, -104.020
Lift-off point
39.750, -104.020
Record number
418

What the Weather Service recorded

A small tornado touched down but did no damage.

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. One was issued for the county at another hour that day.

Issued (UTC)ExpiredProductOffice
20:37 UTC21:00 UTCTornado WarningBOU

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 20:04 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.

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 Denver/Boulder, CO wrote its last area forecast discussion before the tornado touched down at Jul 26, 3:30 AM MDT, 10 hours 45 minutes earlier.

Area forecast discussion, Jul 26, 3:30 AM MDT, 10 hours 45 minutes before
NORTHEAST AND NORTH CENTRAL COLORADO AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER COLORADO
330 AM MDT THU JUL 26 2001

SHORT TERM: STAGE IS SETTING UP FOR AN ACTIVE WEATHER DAY FOR CWA
LATER THIS AFTN AND TONIGHT. MOISTURE PLUME FROM MEXICO CONTINUES
STREAMING INTO CO WITH PW VALUES AROUND AN INCH. MAIN PLAYER FOR OUR
WEATHER WILL BE WEAKENING LOW NOW LIFTING TO THE NORTHEAST ACROSS NW
ARIZONA. THIS TROUGH WILL BE MOVE ACROSS NW CO LATER THIS AFTN AND
WEAKEN AND SHIFT THRU CWA DURING THE NIGHT. DIV-Q FIELDS SHOWING
FAIRLY DECENT UPWARD FORCING ESPECIALLY FOR THE SUMMER TIME. FORCING
IS ALSO AIDED BY 60KT SPEED MAX AS TROF LIFTS ACROSS REGION. AT THE
SURFACE...WEAK SURGE HAS BACKED INTO FAR NERN CO FROM OVERNIGHT
COMPLEX IN NEBRASKA WITH INCREASING LOW LEVEL MOISTURE(SFC DEWPOINTS
IN MID 60S) ON E-SE WINDS. SAT PICS ALSO SHOW STRATUS/FOG MOVING IN
AS WELL. DON'T THINK IT WILL MAKE IT ALL THE WAY BACK TO DEN...BUT
WILL ADD SOME FOG FOR ERN PLAINS ZONES THIS MORNING. WITH THE
INCREASING S-SE FLOW...EXPECT A DENVER CYCLONE OR CONVERGENCE LINE
TO SET UP OVER OR JUST EAST OF THE URBAN COORIDOR DURING THE
AFTERNOON. THIS SHOULD BE THE FOCUS FOR A SEVERE WX SET UP LATER
THIS AFTN/EVENING. 06Z MESOETA SHOWING CAPES AROUND 2000-2500J/KG
EAST OF DENVER OVER THE PLAINS...AND BETWEEN 1000-1500 J/KG FOR
WESTERN PTNS OF CWA. THE DIFFERENCE TODAY IN COMPARISON TO LAST FEW
DAYS IS THE HIGHER CAPES...GREATER LOW LVL MSTR AND STRONGER MID LVL
FLOW. ALSO STORM REL HELICITIES ALSO LOOKING GOOD WITH VALUES
BETWEEN 200-300M2/S2. EXPECT STRONGEST STORMS CAN PRODUCE LARGE HAIL
UP TO 2 INCHES IN DIAMETER AND EVEN AN ISOLATED TORNADO NOT OUT OF
THE QUESTION WITH THIS NICE DIRECTIONAL SHEAR PROFILE SETTING UP.
WILL MENTION POSSILBE SEVERE STORMS IN ZONES FOR TNT OVER THE
PLAINS.

TIMING OF STORMS SHOULD BE ON THE LATE SIDE AGAIN TODAY...WITH
MTNS/HIR TERRAIN GOING FIRST AGAIN BY MID AFTERNOON...URBAN COORIDOR
AND ADJ EAST SECTIONS BTWN 22-00Z...AND EASTERN PLAINS THIS EVENING.
THE LATE FIRING DUE TO MORE CLOUD COVER/FOG EASTERN PTNS THIS
MORNING...AND UPR SUPPORT NOT REALLY IN HERE UNTIL AFT 00Z.

LONG TERM: WEATHER WILL BE CALMING DOWN ON FRIDAY...BUT PIECE OF
TROF LAGGING BEHIND FRI AFTN AND MAY CREATE SOME THUNDERSTORMS OVER
THE FAR EAST PLAINS. WESTERN PTNS OF CWA SHOULD BE DRYING OUT WITH
SUBSIDENCE MOVING IN WITH ISOLD TS COVERAGE AT BEST.  WEEKEND STILL
LOOKING RATHER DRY WITH STRONGER WESTERLY FLOW...BUT CAN'T RULE OUT
AN ISOLD TSRA. UPPER HIGH SHIFTS EAST AGAIN NEXT WEEK AND TS CHANCES
SHOULD INC. THIS COVERED WELL IN ZONES. ENTREKIN

.DEN...NONE.

In the hours before

Special weather statement, Jul 26, 10:30 AM MDT, 3 hours 45 minutes before
COZ030>051-262000-

SIGNIFICANT WEATHER OUTLOOK FOR NORTHEAST AND NORTH CENTRAL COLORADO
NATIONAL WEATHER SERVICE DENVER CO
1030 AM MDT THU JUL 26 2001

THIS OUTLOOK PERTAINS TO THE FOLLOWING COLORADO COUNTIES

ADAMS     ARAPAHOE     BOULDER   CLEAR CREEK   DENVER       DOUGLAS
ELBERT    GILPIN       GRAND     JACKSON       JEFFERSON    LARIMER
LINCOLN   LOGAN        MORGAN    PARK          PHILLIPS     SEDGWICK
SUMMIT    WASHINGTON   WELD

SYNOPSIS:  AN UPPER LEVEL TROUGH...LOCATED OVER NORTHWESTERN ARIZONA
WILL SLOWLY MAKE ITS WAY ACROSS WESTERN AND NORTHERN COLORADO LATE
THIS AFTERNOON AND TONIGHT.  IN ADDITION...SOUTHEASTERLY SURFACE
WINDS ARE EXPECTED TO INCREASE AHEAD OF THIS SYSTEM...ALLOWING THE
LOW LEVEL MOISTURE TO REMAIN IN PLACE ACROSS THE NORTHEASTERN PLAINS
AND URBAN CORRIDOR.

SUFFICIENT SHEAR WILL BE PRESENT FOR THE DEVELOPMENT OF LARGE HAIL
...DAMAGING WINDS AND POSSIBLY AN ISOLATED TORNADO.  HEAVY RAINFALL
...UP TO 2 INCHES PER HOUR...AND FREQUENT CLOUD TO GROUND LIGHTNING
WILL ALSO OCCUR WITH THE STORMS.   THE GREATEST POTENTIAL FOR SEVERE
THUNDERSTORMS APPEARS TO BE EAST OF INTERSTATE 25.

THE MAIN LIMITATION MAY BE THE EXTENSIVE CLOUD COVER PRESENTLY OVER
NORTHEASTERN COLORADO.  THIS MAY DELAY THE ONSET OF THE STRONGER
THUNDERSTORMS UNTIL LATE THIS AFTERNOON.

SCATTERED THUNDERSTORMS WILL DEVELOP IN THE MOUNTAINS AND FOOTHILLS
AFTER 1200 PM...MOVING INTO THE URBAN CORRIDOR AFTER 3 PM.  SPOTTER
ACTIVATION MAY BE NEEDED AT THAT TIME.

COOPER
Special weather statement, Jul 26, 1:15 PM MDT, 1 hour before
COZ030>051-262100-

SIGNIFICANT WEATHER OUTLOOK FOR NORTHEAST AND NORTH CENTRAL COLORADO
NATIONAL WEATHER SERVICE DENVER CO
115 PM MDT THU JUL 26 2001

THIS OUTLOOK PERTAINS TO THE FOLLOWING COLORADO COUNTIES

ADAMS     ARAPAHOE     BOULDER   CLEAR CREEK   DENVER       DOUGLAS
ELBERT    GILPIN       GRAND     JACKSON       JEFFERSON    LARIMER
LINCOLN   LOGAN        MORGAN    PARK          PHILLIPS     SEDGWICK
SUMMIT    WASHINGTON   WELD

SYNOPSIS:  A WEAK UPPER LEVEL DISTURBANCE WILL EXIT NORTHERN
COLORADO EARLY THIS AFTERNOON...WITH THE MAIN UPPER LEVEL TROUGH
EXPECTED TO SLOWLY MAKE ITS WAY ACROSS WESTERN AND NORTHERN COLORADO
TONIGHT.

ENOUGH VERTICAL WIND SHEAR MAY BE PRESENT THROUGH EARLY THIS EVENING
FOR THE DEVELOPMENT OF A FEW SEVERE THUNDERSTORMS.  THESE STORMS
COULD PRODUCE LARGE HAIL...DAMAGING WINDS AND EVEN AN ISOLATED
TORNADO.

HEAVY RAINFALL...UP TO 2 INCHES IN LESS THAN AN HOUR...AND FREQUENT
CLOUD TO GROUND LIGHTNING WILL ALSO OCCUR.  SHOULD THE STORMS REMAIN
STATIONARY OR TRAIN OVER THE SAME LOCATION...THEN POTENTIAL FLOODING
OR FLASH FLOODING PROBLEMS MAY ALSO DEVELOP.

AT 1 PM MDT...SATELLITE DATA INDICATED DRIER AIR IN THE MID LEVELS
WAS MOVING IN FROM THE SOUTH.  IF AFTERNOON TEMPERATURES CAN WARM
INTO THE MID 80S...THEN THE POTENTIAL FOR STRONG TO SEVERE
THUNDERSTORMS WILL INCREASE SIGNIFICANTLY.

THE GREATEST POTENTIAL FOR SEVERE WEATHER APPEARS TO BE ALONG
AND EAST OF A BOUNDARY THAT EXTENDED FROM NEW RAYMER TO BYERS TO
CASTLE ROCK.  SPOTTER ACTIVATION MAY BE NEEDED AFTER 3 PM.

COOPER

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.

Denver, CO (KDNR), 12:00Z

8.3 hours before the tornado, 69 km from the path. July 26, 2001.

Skew-T log-pSkew-T log-p diagram, Denver, CO at 12:00Z on 2001-07-26Temperature 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 -72311, lifted condensation level 1935 meters above ground. Wind barbs in knots down the right edge.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 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, Denver, CO at 12:00Z on 2001-07-26The 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 31 square meters per square second, 0 to 6 km bulk shear 24 knots.193958Sfc1 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
-72311 J/kg
Surface CAPE
0 J/kg
Mixed-layer LCL
1935 m above ground
0-6 km bulk shear
24 kt
0-1 km bulk shear
8 kt
0-1 km storm-relative helicity
31 m²/s²
0-3 km storm-relative helicity
46 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
4.8 K/km

Open this sounding in Storm Lab

Denver, CO (KDNR), 00:00Z

3.7 hours after it, 69 km from the path. July 27, 2001.

Skew-T log-pSkew-T log-p diagram, Denver, CO at 00:00Z on 2001-07-27Temperature 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 -76280, lifted condensation level 2110 meters above ground. Wind barbs in knots down the right edge.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 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, Denver, CO at 00:00Z on 2001-07-27The 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 -46 square meters per square second, 0 to 6 km bulk shear 39 knots.193958Sfc1 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
-76280 J/kg
Surface CAPE
264 J/kg
Mixed-layer LCL
2110 m above ground
0-6 km bulk shear
39 kt
0-1 km bulk shear
10 kt
0-1 km storm-relative helicity
-46 m²/s²
0-3 km storm-relative helicity
4 m²/s²
Significant tornado parameter
0.0
Supercell composite
-0.0
0-3 km lapse rate
8.1 K/km

Open this sounding in Storm Lab

The surface observations

Denver Intnl Airport (DEN), 55 km from the path, in the two hours either side.

Time (UTC)Temp (°F)Dew point (°F)WindGust (kt)Pressure (mb)Weather
18:53 UTC7858320° 11 kt1019.3
19:53 UTC7555310° 17 kt231019.6
20:53 UTC7653320° 20 kt251018.6
21:53 UTC7754330° 12 kt1019

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

The radar

The Denver radar (KFTG), 45 km away, was scanning. The volume nearest the touchdown began at 20:15 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 2001 tornado in ColoradoEvery tornado in Colorado since 1950Warnings in force in Colorado nowThe forecast where you are

The other tornadoes of July 26, 2001

5 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
July 264:30 PM MDTF0Campbell, WY1.020
July 264:40 PM MDTF0Campbell, WY1.020
July 266:35 PM CDTF0McKenzie, ND0.040
July 266:40 PM CDTF0Burke, ND0.040
July 269:20 PM EDTF0Charlotte, FL0.110$3,000

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.