EF1 tornado, Hollister to Grandfield, Oklahoma, April 30, 2024

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

April 30, 2024

Touchdown

9:32 PM CDT (02:32 UTC)

Lifted

10:12 PM CDT (03:12 UTC)

On the ground

40 minutes

Path length

6.4 miles (10.3 km)

Path width

1,200 yards (1097 m)

Deaths

0

Injuries

0

Property damage

$50,000

County

Tillman County

Touchdown point

34.362, -98.832

Lift-off point

34.382, -98.801

Record number

2404302032-01

39 damage points were recorded along this path by NWS OUN, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF1. The highest wind the damage implies is 110 mph.

• Tree branch down. Road too muddy south. May not be considered tornado damage
• Roll of barbed wire that was missing from the house on rd 2360
• Tree damage along edge of forested area
• Edge of the treeline with uprooted and snapped trees

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

A rather nebulous upper air pattern existed across the Southern Plains on the 30th, with 30-40 knots of quasi-zonal flow at 500 mb. However, plentiful solar insolation/surface heating in the vicinity of a dryline fostered widely scattered thunderstorm development by the late afternoon. Strong instability and sufficient organizing wind shear lead to a few of these storms displaying supercellular characteristics and producing reports of large hail initially, owing to steep lapse rates and weak low-level shear (among other factors already mentioned). By the mid-evening, as low-level shear and storm-scale interactions began to increase, a few tornadoes occurred across portions of south-central into southwest Oklahoma. The most significant of these was an EF-1 tornado near the community of Hollister (Tillman County).

This tornado was first observed by a storm chaser at 932 pm CDT and likely formed near County Road E1830 just east of County Road N2320. Over the next 40 minutes, the tornado meandered slowly eastward along E1830 Road then turned northeast reaching near N2360 Road and E1820 Road. The tornado then turned and moved west-northwest along EW1820 Road finally dissipating near N2340 Road. The tornado occurred in a very rural area of Tillman County, although two farm homes were damaged near the easternmost point of the tornado path. A few barns were also damaged, otherwise the damage was primarily to trees and a few power poles. ||Although the damage is rated as EF1, velocity data from the nearby KFDR radar gives strong indication that the tornado may have been much stronger than observed damage would indicate. The maximum observed rotational velocity from KFDR reached 114 knots.

A strong anticyclonic tornado developed between Loveland and Grandfield near the intersection of county roads E1890 and N2370 Roads. Trees were snapped near the beginning of the path, but no other damage was observed or accessible in this very rural area of Tillman County and the remainder of the path is estimated from differences in NDVI satellite imagery. As with the tornado northeast of Hollister, velocity data from nearby KFDR radar indicates that this tornado was likely stronger than the observed damage indicates with the rotational velocity observed from KFDR up to 71 knots.

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

33 minutes of warning. NWS OUN issued a tornado warning for this county at 01:59 UTC, 33 minutes before the tornado touched down, in force until 02:45 UTC.

The county was under a severe thunderstorm watch, issued at 21:38 UTC and running to 03:27 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 Slight Risk, with a 0.05 chance of a tornado within 25 miles. The outlook in force was issued at 01:00 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.

Frederick (FDR), 16 km from the path, in the two hours either side.

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

The Altus AFB radar (KFDR), 15 km away, was scanning. The volume nearest the touchdown began at 02:33 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 2024 tornado in OklahomaEvery tornado in Oklahoma since 1950Warnings in force in Oklahoma nowThe forecast where you are

13 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.