Tornadoes · United States · Oklahoma · 1930

F3 tornado, SW Duncan to NW Duncan, OK, May 5, 1930

Name: F3 tornado, SW Duncan to NW Duncan, OK, May 5, 1930
Start: 1930-05-06T00:30:00.000Z
Location: SW Duncan to NW Duncan, OK

This F3 tornado ran from SW Duncan to NW Duncan, OK on May 5, 1930, touching down at 6:30 PM CST. Its path ran 10.3 miles and was up to 300 yards wide. It killed nobody and injured 7. Before 1950 the record is Thomas P. Grazulis’s list of significant tornadoes: those rated F2 or stronger, and weaker ones that killed somebody.

The rating scale

Tracks are drawn in the color of the rating. Grazulis rated these tornadoes on the Fujita scale decades after the fact, from written accounts of the damage. The scale rates the damage rather than measuring the wind: the speeds are what that damage is taken to imply.

F040 to 72 mph
Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.
F173 to 112 mph
Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.
F2113 to 157 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.
F3158 to 206 mphthis tornado
Severe damage. Whole stories of well-built houses destroyed, large buildings badly damaged, trains overturned, trees debarked, heavy cars lifted and thrown.
F4207 to 260 mph
Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.
F5261 to 318 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.
Unrated
Grazulis gave no rating: the surviving account records a tornado without enough about the damage to rate it. Almost all of these are before 1880.

The record

Rating: F3, assigned by Grazulis from the accounts
Date: May 5, 1930
Time: 6:30 PM CST (00:30 UTC)
Places named: SW Duncan to NW Duncan, OK
Path length: 10.3 miles (16.6 km)
Path width: 300 yards (274 m)
Deaths: 0
Injuries: 7
County today: Stephens County
Drawn from: 34.42, -98.03
Drawn to: 34.57, -98.03
Record: Tornado Archive TPG1309

How the track was drawn

Tornado Archive drew the path as a straight line from the first place Grazulis names to the last. The tornado itself will not have run straight, and the line can miss a town it hit. The counties are today's, and many had other lines, or did not exist, in 1930.

What is not here

The warnings: The Weather Bureau issued its first public tornado forecasts in 1952. The warning archive this site reads begins in 1986.
The outlook: SPC's archive of convective outlooks begins in 1987.
The radar: Weather radar did not watch storms until after the Second World War. The radar archive this site reads begins in 1991.
The Weather Service's narrative: The Storm Events Database, with its narratives and casualty records, begins in 1950.
A damage survey: The Fujita scale dates from 1971, so no tornado before it was rated at the time. The rating here is Grazulis’s, from the accounts.
A sounding: The upper-air archive this site reads begins in the middle 1940s.
Surface observations: No airport observations within 150 km of the path survive in the archive for those hours.

The other tornadoes of May 5, 1930

21 more significant tornadoes are on record that day.

Date	Time	Rating	Where	Path (mi)	Width (yd)	Deaths	Injuries
May 5		F2	E Durant, OK
May 5		F2	Lorraine, KS	1.6
May 5	3:15 PM CST	F2	Maywood, IL		30
May 5	3:30 PM CST	F2	Walters, OK	8.8	200
May 5	3:55 PM CST	F4	NW Holstein to S Highland, NE	11.4	200
May 5	4:00 PM CST	F3	SE Turon to N Langdon, KS	14.9	500		9
May 5	4:20 PM CST	F2	SE Lorraine/NW Ellsworth, KS	19.3	500
May 5	5:15 PM CST	F4	Ellinwood, KS	26.6	400		3
May 5	5:30 PM CST	F2	Park Center/Ely, NE	9.7	60		2
May 5	5:30 PM CST	F2	W Juniata, NE
May 5	5:50 PM CST	F4	NE Walters, OK	7.2	1,000	1	16
May 5	6:00 PM CST	F3	E Greenfield to SE Watonga, OK	10.1	600	3	18
May 5	6:00 PM CST	F2	SE Lincoln/E Barnard, KS	21.7	440		2
May 5	6:15 PM CST	F2	SE St. Libory, NE	8.4
May 5	6:15 PM CST	F2	NE Doniphan, NE
May 5	7:00 PM CST	F4	Greeley, NE	15.2	200		5
May 5	7:00 PM CST	F3	SW Albion, NE
May 5	7:00 PM CST	F2	SE Petersburg, NE	5.0	50	1
May 5	7:45 PM CST	F2	S Chase, KS	12.2			2
May 5	10:40 PM CST	F4	NE Rush Springs, OK	4.0	400	2	9
May 5	11:00 PM CST	F3	SW Solomon to NE Riley, KS	50.0	100		18

This ground now

The live radar over the track Every 1930 tornado in Oklahoma Every tornado in Oklahoma Warnings in force in Oklahoma now

About the record before 1950

Significant tornadoes only: Grazulis listed tornadoes rated F2 or stronger, and weaker ones that killed somebody. Most tornadoes are weaker than F2, so the list holds a fraction of the tornadoes that happened.
The early years are thin: A tornado is on record only where somebody saw it and wrote it down. The count rises through the 1800s with settlement and newspapers, not with the weather.
Rated from accounts: Grazulis rated each tornado decades later from newspaper reports, Weather Bureau records and local histories, not from a damage survey.
The tracks are reconstructed: Tornado Archive drew each path through the places Grazulis names, most often as a straight line from the first to the last. A track can miss a town it hit, and a tornado with one named place is a point. The counties are today’s.
A separate record: SPC’s database, from 1950, counts every confirmed tornado of any strength. The two are kept apart on every page and never added together.

What this means

Ratings are Grazulis's, read from written accounts of the damage; the rating scale is above. About the record before 1950 says what it holds and what it leaves out.

Sources

Thomas P. Grazulis, Significant Tornadoes 1680-1991 and Significant Tornadoes 1880-1989, as digitized by Tornado Archive (Maas and others, 2024). Public domain. Counties assigned by this site from today’s NWS county lines.