Tornadoes · United States · Iowa · 2019

Unrated tornado, Fletcher Chapel, Iowa, July 16, 2019

This Unrated tornado ran 1.4 miles across Cass County on July 16, 2019, touching down at 3:38 PM CDT and reaching 30 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 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. Unratedthis tornado

    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
Unrated
Date
July 16, 2019
Touchdown
3:38 PM CDT (20:38 UTC)
Lifted
3:43 PM CDT (20:43 UTC)
On the ground
5 minutes
Path length
1.4 miles (2.3 km)
Path width
30 yards (27 m)
Deaths
0
Injuries
0
Crop damage
$500
County
Cass County
Touchdown point
41.312, -94.971
Lift-off point
41.292, -94.964
Record number
1907161438-01

What the Weather Service recorded

A juicy atmosphere with a lack of organizational support (effective bulk shear) made for a messy convective environment across portions of the state on the 16th. During the morning hours convection from central and eastern Nebraska drifted into western Iowa, producing heavy rainfall. Another round of developed across northwest Iowa during the morning and rolled across northern Iowa and southern Minnesota, producing a lone severe wind gust. Later in the afternoon, storms were able to initiate along old outflow boundaries and were able to produce localized heavy rainfall, a weak tornado, and a other funnel cloud reports. ||While support was lackluster, there were indications for the possibility of a funnel cloud or weak tornado during the afternoon with supportive SBCAPE in excess of 2000 J/kg, weak boundaries in the area, and most importantly very supportive 0-3km cape values in excess of 150 J/kg for low level stretching.

Weak tornado captured on camera/video. Remained over open land and was rated EF-Unknown as no damage indicators were impacted.

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
19:37 UTC20:15 UTCTornado WarningDMX
20:40 UTC21:04 UTCTornado WarningDMX

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 Marginal Risk. The outlook in force was issued at 19:45 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.

Omaha, NE (KOAX), 12:00Z

8.6 hours before the tornado, 117 km from the path. July 16, 2019.

Skew-T log-pSkew-T log-p diagram, Omaha, NE at 12:00Z on 2019-07-16Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 259 joules per kilogram, CIN -142, lifted condensation level 836 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, Omaha, NE at 12:00Z on 2019-07-16The 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 -81 square meters per square second, 0 to 6 km bulk shear 25 knots.1939Sfc1 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
259 J/kg
Mixed-layer CIN
-142 J/kg
Surface CAPE
430 J/kg
Mixed-layer LCL
836 m above ground
0-6 km bulk shear
25 kt
0-1 km bulk shear
17 kt
0-1 km storm-relative helicity
-81 m²/s²
0-3 km storm-relative helicity
-81 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
5.0 K/km

Open this sounding in Storm Lab

Omaha, NE (KOAX), 00:00Z

3.4 hours after it, 117 km from the path. July 17, 2019.

Skew-T log-pSkew-T log-p diagram, Omaha, NE at 00:00Z on 2019-07-17Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 1673 joules per kilogram, CIN -31, lifted condensation level 1344 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, Omaha, NE at 00:00Z on 2019-07-17The 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 35 square meters per square second, 0 to 6 km bulk shear 23 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
1673 J/kg
Mixed-layer CIN
-31 J/kg
Surface CAPE
2863 J/kg
Mixed-layer LCL
1344 m above ground
0-6 km bulk shear
23 kt
0-1 km bulk shear
10 kt
0-1 km storm-relative helicity
35 m²/s²
0-3 km storm-relative helicity
124 m²/s²
Significant tornado parameter
0.0
Supercell composite
2.8
0-3 km lapse rate
7.2 K/km

Open this sounding in Storm Lab

The radar

The Des Moines radar (KDMX), 114 km away, was scanning. The volume nearest the touchdown began at 20:37 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
19:28 UTCFUNNEL CLOUD4 Nnw CumberlandCass, IABRIEF FUNNEL CLOUD REPORTED SOUTH OF ATLANTIC.
19:40 UTCTORNADO8 Se AtlanticCass, IA

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

This ground now

The live radar over the trackEvery 2019 tornado in IowaEvery tornado in Iowa since 1950Warnings in force in Iowa nowThe forecast where you are

The other tornadoes of July 16, 2019

3 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
July 1612:17 PM CDTEF0Marshall, MS5.375$750,000
July 165:35 PM CDTEF0Waushara, WI0.110
July 167:34 PM MDTEF0Campbell, WY1.210

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.