EF1 tornado, Big Fork to Pine Ridge, Arkansas, April 25, 2011

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 25, 2011

Touchdown

2:55 PM CDT (19:55 UTC)

Lifted

3:02 PM CDT (20:02 UTC)

On the ground

7 minutes

Path length

5.8 miles (9.4 km)

Path width

50 yards (46 m)

Deaths

0

Injuries

0

Property damage

$250,000

Counties

Polk and Montgomery counties

Touchdown point

34.498, -93.994

Lift-off point

34.551, -93.915

Record number

1104251355-01

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

• .large limbs off of trees.
• .Large trees snapped in half.
• .Large portion of roof removed. Large trees uprooted along with large limbs snapped off. Large storage building destroyed. Adjacent chicken houses with moderate damage. Damage width 50-75 yards wide.

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

From the 24th through the 27th, the arrival of a slow-moving cold front and several low pressure areas aloft triggered several rounds of thunderstorms. Tornadoes, severe storms, and flash flooding resulted. Widespread areal flooding followed the flash flooding. Some of this flooding was due to heavy rain, while some of it was caused by water from rivers, creeks, and bayous backing up onto the land. On the evening of the 25th, devastating tornadoes affected several areas in central Arkansas. More than 140,000 electric customers in Arkansas lost power. Heavy rains during this period were the beginning of the Great Flood of 2011 in Arkansas. Much of the flooding lasted well into May, and some even continued all the way to late June.

A tornado blew down numerous trees and power lines. The tornado exited Polk County east-northeast of Opal and entered Montgomery County southwest of Pine Ridge.

This tornado exited Polk County east-northeast of Opal and entered Montgomery County southwest of Pine Ridge. In Montgomery County, numerous trees and some power lines were blown down.

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

20 minutes of warning. NWS LZK issued a tornado warning for this county at 19:35 UTC, 20 minutes before the tornado touched down, in force until 20:00 UTC.

The county was under a tornado watch, issued at 16:05 UTC and running to 20:25 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 Moderate Risk, with a 0.15 chance of a tornado within 25 miles, in the hatched area where significant tornadoes were expected. The outlook in force was issued at 16:29 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 Western Arkansas radar (KSRX), 93 km away, was scanning. The volume nearest the touchdown began at 19:56 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 2011 tornado in ArkansasEvery tornado in Arkansas since 1950Warnings in force in Arkansas nowThe forecast where you are

45 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.