EF0 tornado, Rush Pt, Minnesota, July 18, 2020

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

July 18, 2020

Touchdown

1:17 AM CDT (06:17 UTC)

Lifted

1:19 AM CDT (06:19 UTC)

On the ground

2 minutes

Path length

1.3 miles (2.0 km)

Path width

75 yards (69 m)

Deaths

0

Injuries

0

County

Chisago County

Touchdown point

45.672, -93.101

Lift-off point

45.663, -93.078

Record number

2007180017-01

36 damage points were recorded along this path by NWS MPX, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF1. The highest wind the damage implies is 93 mph.

• 90 degree angle. one down to nw, on to se.
• lights drawn upward through roof
• boat lift blown to the south. trees damaged in the distance.
• soffit and fascia off house in spots. Neighbor has anemometer that hit 87.

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

During the evening of Friday, July 17th, a line of strong to severe thunderstorms that developed across northwest Minnesota, propagated south-southeast across central Minnesota and became a well defined bow echo segment. There were two areas that had the worst damage. One occurred in Stevens County where a swath of wind damage extended 3/4 of a mile to the southeast of Chokio, and about 1/4 of a mile wide. Many trees were snapped off just above the base, while others were uprooted. The second area was associated with straight-line winds, occasional downbursts, and two tornadoes that hit northern Isanti, and northern Chisago Counties. ||There was ample instability and wind shear during the evening to hold supercell characteristics along this bow echo segment. As the storm bowed out to the southeast late in the evening, less instability and wind shear diminished the organized nature of the bow segment. However, a one bow echo segment allowed for two tornadic storms near Day and Rush City. ||There was continued weakening of this bow echo overnight, with more individual line segments which caused brief, and isolated wind damage. Even local airport wind sensors, and private wind sensors were measuring wind gusts in the 40 to 50 mph range past midnight LST. The exception was in the Twin Cities metro area where the Flying Cloud airport measured a wind gust of 59 mph, and the Minneapolis/St. Paul airport measured a wind gust of 55 mph.

A brief tornado cross the southern portion of West Rush Lake, uprooting trees and knocking down numerous large branches. It flipped several boat docks and pontoons. Some debris from the docks was blown 1/2 mile downwind into some trees.

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

14 minutes of warning. NWS MPX issued a tornado warning for this county at 06:03 UTC, 14 minutes before the tornado touched down, in force until 06:30 UTC.

The county was under a severe thunderstorm watch, issued at 03:29 UTC and running to 07:59 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 06:00 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.

The Minneapolis radar (KMPX), 98 km away, was scanning. The volume nearest the touchdown began at 06:19 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 2020 tornado in MinnesotaEvery tornado in Minnesota since 1950Warnings in force in Minnesota nowThe forecast where you are

5 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.