Tornadoes · United States · Illinois · 2024

Unrated tornado, Dakota Dornink Arpt, Illinois, July 15, 2024

This Unrated tornado ran 1.0 miles across Stephenson County on July 15, 2024, touching down at 7:26 PM CDT and reaching 10 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 15, 2024
Touchdown
7:26 PM CDT (00:26 UTC)
Lifted
7:27 PM CDT (00:27 UTC)
On the ground
1 minutes
Path length
1.0 miles (1.6 km)
Path width
10 yards (9 m)
Deaths
0
Injuries
0
County
Stephenson County
Touchdown point
42.370, -89.580
Lift-off point
42.370, -89.560
Record number
2407151826-01

The damage survey

10 damage points were recorded along this path by NWS DVN and NWS LOT, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EFU. The highest wind the damage implies is 107 mph.

  • One farm outbuilding collapsed with debris pushed eastward into an adjacent outbuilding. Part of north-facing roof peeled back slightly on another nearby farm outbuilding, and several large tree branches downed at this property.
  • Tree snapped and downed to the south-southeast
  • Several large tree limbs snapped off from this row of trees and downed to the southeast.
  • Top of large tree snapped off, downed to the southeast

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

Thunderstorms rapidly developed over northern Iowa during the afternoon and organized into a powerful line of wind producing storms that surged through the Quad Cities and into northern and central Illinois through the evening hours. These storms brought widespread damaging winds up to 100 mph for many locations, extending across eastern Iowa, much of Illinois, and into Indiana. The Storm Prediction Center has classified this event as a Derecho which by definition is a swath of wind damage at least 400 miles long and at least 60 miles wide including several well-separated significant wind gusts over 75 mph. Corridors of significant wind damage occurred along Highway 20. 10 tornadoes also occurred with these storms in the NWS Quad Cities service area. ||In addition to the wind, very heavy rainfall fell in a short amount of time with many locations seeing over an inch. The highest totals fell in McDonough and Warren counties in Illinois where amounts between 2 and 3 inches fell.

A trained spotter video confirmed a short-lived tornado southwest of Dakota, or northeast of Freeport. There was no observed damage to assign a rating.

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 Quad Cities, IA wrote its last area forecast discussion before the tornado touched down at Jul 15, 6:19 PM CDT, 1 hour 7 minutes earlier. Its key messages:

  • A Heat Advisory is in effect area-wide today until 8 PM for peak heat indices between 100 to 100 degrees.
  • Today's severe thunderstorm outlook has been upgraded to a Moderate Risk (level 4 of 5) for the northern two-thirds of the forecast area. The Enhanced Risk (level 3 of 5) remains to the south. Significant damaging winds are the primary hazard; several tornadoes are also possible.
  • A Flood Watch as been issued for counties east and northeast of the Quad Cities. Recent heavy rainfall has saturated the ground, making this area more susceptible to flash flooding. Rainfall rates could peak between 2 - 2.5" per hour.
  • Moderate to major river flooding continues on the Mississippi River with most sites crested. The Rock River is now expected to see flooding due to the heavy rains upstream in the past 24 hours.
Area forecast discussion, Jul 15, 6:19 PM CDT, 1 hour 7 minutes before
Area Forecast Discussion
National Weather Service Quad Cities IA IL
Issued by National Weather Service Paducah KY
619 PM CDT Mon Jul 15 2024

.KEY MESSAGES...

- A Heat Advisory is in effect area-wide today until 8 PM for
  peak heat indices between 100 to 100 degrees.

- Today's severe thunderstorm outlook has been upgraded to a
  Moderate Risk (level 4 of 5) for the northern two-thirds of
  the forecast area. The Enhanced Risk (level 3 of 5) remains
  to the south. Significant damaging winds are the primary
  hazard; several tornadoes are also possible.

- A Flood Watch as been issued for counties east and northeast
  of the Quad Cities. Recent heavy rainfall has saturated the
  ground, making this area more susceptible to flash flooding.
  Rainfall rates could peak between 2 - 2.5" per hour.

- Moderate to major river flooding continues on the Mississippi
  River with most sites crested. The Rock River is now expected
  to see flooding due to the heavy rains upstream in the past 24
  hours.

&&

.SHORT TERM /THROUGH TUESDAY NIGHT/...
Issued at 256 PM CDT Mon Jul 15 2024

There is a Moderate Risk (level 4 of 5) for severe weather this
afternoon into tonight for much of the outlook area, with an
Enhanced Risk (level 3 of 5) across the south. Please monitor
the weather closely and heed any warnings issued for your
location!

SPC mesoanalysis early this afternoon showed a mid-level
vorticity max across E South Dakota/SW Minnesota/NW Iowa,
positioned to the south of a 80 kt 300mb jet over northern
Minnesota and Wisconsin. A zone of low-level moisture
convergence was noted (where surface dewpoints were between 75
to 80 degrees!), stretching from central Iowa to the Quad
Cities and into central Illinois.

As large-scale ascent associated with the mid-level impulse
overspreads the area late this afternoon/evening, this quasi-
stationary zone of low- level convergence may aid in focusing
the convective initiation. With extreme instability in place
(3500 - 4500 J/kg MLCAPE), anticipate explosive convective
development and rapid upscale growth into one, or possible a
few, bowing line segments. Forward-propagating Corfidi vectors
and W to SE sloping theta-e and 1000-500mb thickness contours
should help in eventually guiding the MCS to the ESE or SE later
into the evening. CAMs have been consistent on showing
significant severe wind gusts in the strongest bowing segments
and the HREF max wind gust output shows several corridors with
values of 60-70+ kts. Greatest uncertainty is on the exact
placement/track of the dominant surging MCS, with a northern
scenario focused across the NE forecast area (NW Illinois) and
another camp further south which would bring significant winds
to a larger portion of eastern Iowa and northwest Illinois.

To reiterate, today is a favorable setup for a higher end wind
event (scattered 75+ mph gusts) due to a very unstable air mass,
sufficient deep layer shear, steep mid-level lapse rates near 8
C/km, and theta-e index values near 35. A few tornadoes are
possible in association with any surging storm segments as 0-3
km shear of 30+ kts supports development of mesovortices.

There is also potential for very heavy rainfall with PWATs near
2". There could be a zone of training convection that leads to
heavy rainfall totals of 2-4"+. WPC has a Slight Risk for flash
flooding across the outlook area.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Issued at 256 PM CDT Mon Jul 15 2024

Cooler and less humid air will move into the region behind a
cold front by Tuesday and last through the end of the week.
Overnight lows in the 50s are forecast on several nights, giving
our air conditioning a bit of a break.

&&

.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 619 PM CDT Mon Jul 15 2024

Convection will pose a significant hazard to operations through
the next few hours. Measured wind gusts at ground level of 70-80
kts have been reported in the last hour. This system will likely
approach the KMLI-KDVN-KCLI corridor at similiar intensity and
may produce winds over 50 kt as far south as KBRL. Ceilings and
visibility will drop to near IFR and heavy thunderstorms and
gusty winds may persist for around an hour before moving to the
southeast. Areas of heavy rain may aid in fog formation in the
early morning hours Tuesday with drier west winds and VFR
conditions forecast for the daytime hours Tuesday.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...None.
IL...None.
MO...None.

&&

SHORT TERM...Uttech
LONG TERM...Ervin/Uttech
AVIATION...JGG
Hazardous weather outlook, Jul 15, 3:45 PM CDT, 3 hours 41 minutes before
Hazardous Weather Outlook
National Weather Service Quad Cities IA IL
345 PM CDT Mon Jul 15 2024

IAZ040>042-051>054-063>068-076>078-087>089-098-099-ILZ001-002-007-
009-015>018-024>026-034-035-MOZ009-010-162045-
Buchanan-Delaware-Dubuque-Benton-Linn-Jones-Jackson-Iowa-Johnson-
Cedar-Clinton-Muscatine-Scott-Keokuk-Washington-Louisa-Jefferson-
Henry IA-Des Moines-Van Buren-Lee-Jo Daviess-Stephenson-Carroll-
Whiteside-Rock Island-Henry IL-Bureau-Putnam-Mercer-Henderson-
Warren-Hancock-McDonough-Scotland-Clark-
345 PM CDT Mon Jul 15 2024

This Hazardous Weather Outlook is for portions of north central
Illinois...northwest Illinois...west central Illinois...east
central Iowa...northeast Iowa...southeast Iowa and northeast
Missouri.

.DAY ONE...THIS AFTERNOON AND TONIGHT

The Storm Prediction Center has a Moderate risk, level 4 of 5, for
this afternoon and evening for much of eastern Iowa and northwest
Illinois. Very damaging winds to 85 mph, very large hail and a
few tornadoes are likely. Torrential rain producing flash
flooding is also possible. There is a flash flood watch for much
of northwest Illinois through tonight.

There is an Enhanced risk, level 3 of 5, for southeast Iowa,
northeast Missouri, and western Illinois.

Supercell thunderstorms with tornadoes and very large hail would
initially be most likely in areas north of Interstate 80 this
afternoon and early evening, followed by a damaging wind producing
line of storms, moving from west to east towards early evening.
Late in the evening, storms will become widespread and sink
southward, and heavy rain will become the primary threat.

Hot and humid conditions will be over the area through early this
evening, with heat index readings topping between 100 and 110
degrees. A Heat Advisory is in effect through 8 PM.

Area rivers are experiencing flooding. Please see the
latest Flood Statements and Flood Warnings for details.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

The probability for widespread hazardous weather is low.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will be needed through tonight.

GENERAL STORM MOTION OF THE DAY:

Toward the east around 30 mph this afternoon then southeast 45 to
60 mph this evening.

Haase

In the hours before

Local storm report, Jul 15, 6:53 PM CDT, 33 minutes before
Preliminary Local Storm Report
National Weather Service Quad Cities IA IL
653 PM CDT Mon Jul 15 2024

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0632 PM     Rain             1 SE Marengo            41.79N 92.06W
07/15/2024  M1.20 Inch       Iowa               IA   Trained Spotter

            Rainfall in 17 min.

&&

GROSS
Local storm report, Jul 15, 7:01 PM CDT, 25 minutes before
Preliminary Local Storm Report
National Weather Service Quad Cities IA IL
701 PM CDT Mon Jul 15 2024

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0621 PM     Tstm Wnd Dmg     2 N Dubuque Regional Ar 42.42N 90.72W
07/15/2024                   Dubuque            IA   Public

            Large tree down across Military Rd.

&&
Local storm report, Jul 15, 7:08 PM CDT, 18 minutes before
Preliminary Local Storm Report
National Weather Service Quad Cities IA IL
708 PM CDT Mon Jul 15 2024

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0656 PM     Tstm Wnd Gst     3 N Stockton            42.40N 90.00W
07/15/2024  M84 MPH          Jo Daviess         IL   CO-OP Observer

&&

GROSS
Local storm report, Jul 15, 7:09 PM CDT, 17 minutes before
Preliminary Local Storm Report
National Weather Service Quad Cities IA IL
709 PM CDT Mon Jul 15 2024

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0605 PM     Tstm Wnd Dmg     2 ENE Cedar Rapids Muni 41.89N 91.68W
07/15/2024                   Linn               IA   Trained Spotter

            3.5 inch tree limb down.

&&
Local storm report, Jul 15, 7:10 PM CDT, 16 minutes before
Preliminary Local Storm Report
National Weather Service Quad Cities IA IL
710 PM CDT Mon Jul 15 2024

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0700 PM     Tstm Wnd Dmg     3 N Stockton            42.40N 90.00W
07/15/2024                   Jo Daviess         IL   CO-OP Observer

            Several tree branches down of various
            diameter down once that is 1 foot and a
            half.

&&

GROSS
Local storm report, Jul 15, 7:22 PM CDT, 4 minutes before
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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.

Davenport, (KDVN), 00:00Z

0.4 hours before the tornado, 113 km from the path. July 16, 2024.

Skew-T log-pSkew-T log-p diagram, Davenport, at 00:00Z on 2024-07-16Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 3794 joules per kilogram, CIN -40, lifted condensation level 1052 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, Davenport, at 00:00Z on 2024-07-16The 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 157 square meters per square second, 0 to 6 km bulk shear 37 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
3794 J/kg
Mixed-layer CIN
-40 J/kg
Surface CAPE
4986 J/kg
Mixed-layer LCL
1052 m above ground
0-6 km bulk shear
37 kt
0-1 km bulk shear
21 kt
0-1 km storm-relative helicity
157 m²/s²
0-3 km storm-relative helicity
341 m²/s²
Significant tornado parameter
5.6
Supercell composite
33.4
0-3 km lapse rate
6.6 K/km

Open this sounding in Storm Lab

The surface observations

Freeport (FEP), 14 km from the path, in the two hours either side.

Time (UTC)Temp (°F)Dew point (°F)WindGust (kt)Pressure (mb)Weather
00:00 UTC

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

The radar

The Milwaukee radar (KMKX), 107 km away, was scanning. The volume nearest the touchdown began at 00:27 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 2024 tornado in IllinoisEvery tornado in Illinois since 1950Warnings in force in Illinois nowThe forecast where you are

The other tornadoes of July 15, 2024

61 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
July 157:14 AM CDTEF0Chippewa, MN2.225
July 153:50 PM EDTEF0Genesee, NY0.875
July 154:48 PM EDTEF0Ontario, NY0.875
July 156:25 PM EDTEF0Cortland, NY7.5175$37,000
July 155:37 PM CDTEF1Polk, IA6.9300$500,000
July 156:54 PM EDTEF1Chenango, NY8.7250$120,000
July 156:14 PM CDTEF1Grant, WI0.330$35,000
July 156:18 PM CDTEF0Jones, IA1.550
July 156:40 PM CDTEF1Jo Daviess, IL29.8100
July 156:48 PM CDTEF1Jo Daviess, IL8.150
July 156:50 PM CDTEF2Jo Daviess, IL15.4150
July 157:02 PM CDTEF0Muscatine, IA to IL3.050
July 157:17 PM CDTEF1Rock Island, IL24.7100
July 157:19 PM CDTEF1Scott, IA to IL8.0100
July 157:26 PM CDTEF0Rock, WI1.250
July 157:44 PM CDTEF0Ogle, IL5.3200
July 157:58 PM CDTEF0Ogle, IL1.7150
July 157:58 PM CDTEF0Winnebago, IL1.2100
July 158:01 PM CDTEF0Winnebago, IL0.225
July 158:02 PM CDTEF1Henry, IL5.2200$100,000
July 158:05 PM CDTEF0Ogle, IL2.2150
July 158:07 PM CDTEF1Knox, IL1.3150
July 158:07 PM CDTEF1Henry, IL1.750$50,000
July 158:15 PM CDTEF0Peoria, IL4.380
July 158:21 PM CDTEF1Peoria, IL2.4150
July 158:25 PM CDTEF0Peoria, IL2.5100
July 158:36 PM CDTEF1Woodford, IL0.4100
July 158:38 PM CDTEF0Woodford, IL1.480
July 158:38 PM CDTUnratedDeKalb, IL1.850
July 158:39 PM CDTEF1Woodford, IL1.2100
July 158:39 PM CDTEF1Tazewell, IL12.2100
July 158:49 PM CDTEF1Kane, IL8.4300
July 158:51 PM CDTUnratedTazewell, IL0.980
July 158:52 PM CDTEF0Kane, IL10.1250
July 158:55 PM CDTEF1Kendall, IL19.2200
July 158:55 PM CDTEF0Woodford, IL3.830
July 159:06 PM CDTEF1Kendall, IL19.52502
July 159:09 PM CDTEF2Grundy, IL34.63252
July 159:10 PM CDTEF0Kendall, IL17.0300
July 159:23 PM CDTEF0DuPage, IL3.1150
July 159:29 PM CDTEF0DuPage, IL0.850
July 159:33 PM CDTEF0Will, IL2.9300
July 159:34 PM CDTEF0DuPage, IL4.1250
July 159:35 PM CDTEF0Kankakee, IL12.3275
July 159:36 PM CDTEF0Cook, IL1.2175
July 159:37 PM CDTEF1Cook, IL2.175
July 159:41 PM CDTEF0Will, IL6.4100
July 159:41 PM CDTEF0Cook, IL5.7300
July 159:43 PM CDTEF1Cook, IL5.5250
July 159:43 PM CDTEF0Cook, IL0.485
July 159:45 PM CDTEF0Cook, IL0.4125
July 159:47 PM CDTEF1Cook, IL3.2150
July 159:47 PM CDTEF1Cook, IL3.1400
July 159:50 PM CDTEF0Cook, IL1.4150
July 159:51 PM CDTEF1Kankakee, IL2.6100
July 159:52 PM CDTEF1Lake, IL to IN29.1300
July 159:58 PM CDTEF0Lake, IN2.4100
July 1510:02 PM CDTEF0Lake, IN16.4100
July 1510:32 PM CDTEF1LaPorte, IN3.275$100,000
July 1512:09 AM EDTEF0Marshall, IN0.775$20,000

All 62 of them

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.