EF0 tornado, Mt Pleasant to Unionville, Maryland, May 3, 2021

1. EF065 to 85 mphthis tornado

   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. 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

EF0

Date

May 3, 2021

Touchdown

8:35 PM EDT (00:35 UTC)

Lifted

8:36 PM EDT (00:36 UTC)

On the ground

1 minutes

Path length

0.6 miles (1.0 km)

Path width

150 yards (137 m)

Deaths

0

Injuries

0

Property damage

$100,000

County

Frederick County

Touchdown point

39.482, -77.153

Lift-off point

39.490, -77.147

Record number

2105031835-01

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

• Unidirectional damage, power lines down.
• Damage path begins ~125 yards past start of tree line. Nearly all trees along this section were topped of their branches or snapped down in multiple directions.
• Trees down near MD 26 and MD 550.
• Reported by county emergency management.

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

An isolated, cyclic supercell thunderstorm tracking along a warm front produced sporadic straight-line wind damage and spawned several tornadoes.

A supercell thunderstorm produced a tornado during the evening|hours of Monday, May 3rd in a rural area of Frederick County, MD,|between Mt Pleasant and Libertytown. An estimated 150 trees were|uprooted, snapped or damaged along the path of the tornado that|moved in an east-northeast direction for approximately three-|quarters of a mile.||Tree damage from this tornado began near a residence in the 10800|block of Old Annapolis Road, with a few snapped large branches|that fell across Old Annapolis Road. The tornado tracked east-|northeast across a large grouping of trees between Old Annapolis|Road and Chestnut Grove Road, damaging approximately 90-100 trees|with multiple large branches snapped, trees uprooted and trunks|snapped in varying directions.||As the tornado crossed Chestnut Grove Road just north of Alton|Road, a large amount of tree damage occurred, with an estimated|40-50 trees uprooted in multiple directions while about 20 trees|were snapped. Isolated tree damage was noted outside of this path|on the southern extent of the tornado path, with a few tree snaps|noted. No structural damage was observed anywhere along the|tornado path.||As the tornado moved further east-northeast and away from|Chestnut Grove Road, it lifted, as no damage was evident or|reported along what would have been a continuation of the|tornados path. Sporadic, straight-line wind damage was noted|further northeast near Libertytown.

After producing a confirmed tornado earlier in Frederick County,|Maryland, near Mt. Pleasant, a supercell thunderstorm produced|another brief tornado further east shortly after 8:30 P.M. EDT in|extreme east-central Frederick County, Maryland, near Unionville.||Damage from this tornado was largely confined to a farm in the|14700 block of Barnes Road that suffered tree and farm equipment|damage, and structural damage to large sheds. The tornado|initially touched down there as it entered a wooded area, carving|a clear path through a section of large trees, with most trees|falling in a convergent manner on the southwest side of a farm.|Slightly more trees were uprooted than snapped, but both were|evident.||As the tornado exited the woods it pushed over a piece of farm|equipment and scattered debris across the farm field. As it|crossed the center of the farm with the majority of the structures|and equipment, substantial damage occurred. Three large farm|sheds were severely damaged or destroyed. Farm equipment was|moved. Calf hutches were thrown north, northeast into the field.|Other sheds were damaged and had debris thrown to the southeast.|The tornado lifted as it reached the northeast end of the farm.

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

24 minutes of warning. NWS LWX issued a tornado warning for this county at 00:11 UTC, 24 minutes before the tornado touched down, in force until 00:45 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 General Thunderstorms Risk. The outlook in force was issued at 19:40 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.

The Sterling radar (KLWX), 64 km away, was scanning. The volume nearest the touchdown began at 00:32 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 2021 tornado in MarylandEvery tornado in Maryland since 1950Warnings in force in Maryland nowThe forecast where you are

30 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.