EF1 tornado, Castleton to Milo, Illinois, February 28, 2017

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.

Rating

EF1

Date

February 28, 2017

Touchdown

4:12 PM CST (22:12 UTC)

Lifted

4:20 PM CST (22:20 UTC)

On the ground

8 minutes

Path length

5.5 miles (8.9 km)

Path width

100 yards (91 m)

Deaths

0

Injuries

0

Property damage

$100,000

Counties

Stark and Bureau counties

Touchdown point

41.111, -89.713

Lift-off point

41.161, -89.631

Record number

1702281612-01

2 damage points were recorded along this path by NWS DVN, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF1. The highest wind the damage implies is 95 mph.

• apparent tornado beginning

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

An unseasonably warm and humid airmass was in place across central Illinois on February 28th...with afternoon high temperatures soaring to record levels in the upper 60s and lower 70s. Thanks to these extremely warm temperatures and dewpoints surging into the upper 50s and lower 60s, Convective Available Potential Energy (CAPE) values exceeded 1500J/kg across Missouri and the western half of Illinois by late afternoon. In addition, a strong mid-level jet streak enhanced 0-6km wind shear to an impressive 60-70kt. While the airmass within the warm sector was initially capped, an approaching upper wave helped weaken the cap and set the stage for strong to severe thunderstorms into the evening. As a cold front pushed across the Mississippi River, supercell thunderstorms initiated across west-central Illinois during the late afternoon and lingered into the evening. These storms produced a total of 4 tornadoes in the National Weather Service Lincoln County Warning Area (CWA), including an EF-3 tornado that touched down west of Washburn in Woodford County. Other storms produced scattered reports of large hail and damaging winds across the area.

Following a week of record highs, a late winter severe weather outbreak brought widespread severe thunderstorms to Iowa, Illinois, and northeast Missouri. Supercell thunderstorms produced numerous reports of large hail and a few tornadoes. The tornadoes were the first ever recorded in the month of February, across eastern Iowa and northwest Illinois. Additionally, some damaging winds occurred after dark, when the storms formed into a line as they moved through Illinois. This outbreak of severe weather also included many locations in the southern half of Illinois, and Missouri.

A tornado touched down 0.8 miles southwest of Castleton at 4:12 PM CST. The tornado then tracked northeastward...damaging trees, an outbuilding, and a few homes before crossing into extreme southwestern Bureau County in the National Weather Service Davenport County Warning Area (CWA) at 4:19 PM CST.

This tornado touched down and spent most of its time moving through Stark County, Illinois, generally south of Bradford and just east of Castleton. It lifted in far western Bureau county. Trees were damaged by this tornado, along with a farm outbuilding, and minor damage to a few homes. The estimated peak wind was 95 mph. The entire path length was 5.51 miles, after initially touching down 5.3 miles southwest of Bradford, 41.11 N / -89.7145 W.

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

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

The county was under a tornado watch, issued at 21:01 UTC and running to 03:58 UTC.

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 Storm Prediction Center had this point in a Enhanced Risk, with a 0.10 chance of a tornado within 25 miles, in the hatched area where significant tornadoes were expected. The outlook in force was issued at 19:56 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 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.

Lacon (C75), 27 km from the path, in the two hours either side.

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

The Quad Cities radar (KDVN), 92 km away, was scanning. The volume nearest the touchdown began at 22:13 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.

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

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

The live radar over the trackEvery 2017 tornado in IllinoisEvery tornado in Illinois since 1950Warnings in force in Illinois nowThe forecast where you are

29 more were confirmed in the United States that day.

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.

NOAA Storm Prediction Center tornado database, 1950-2025, the official record kept by NOAA's Storm Prediction Center.