Tornadoes · United States · North Dakota · 2017

EF0 tornado, Hamar, North Dakota, June 9, 2017

Name: EF0 tornado, Hamar, North Dakota, June 9, 2017
Start: 2017-06-10T01:29:00.000Z
End: 2017-06-10T01:33:00.000Z
Location: Hamar, North Dakota

This EF0 tornado ran 3.0 miles across Eddy County on June 9, 2017, touching down at 8:29 PM CDT and reaching 150 yards wide. It killed nobody, and did $10,000 of property damage.

The rating scale

Tracks are drawn in the color of the rating. The Enhanced Fujita scale rates the damage rather than measuring the wind: the speeds are what that damage is taken to imply.

EF065 to 85 mphthis tornado
Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.
EF186 to 110 mph
Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.
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.
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.
EF4166 to 200 mph
Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.
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.
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.

The record

Rating: EF0
Date: June 9, 2017
Touchdown: 8:29 PM CDT (01:29 UTC)
Lifted: 8:33 PM CDT (01:33 UTC)
On the ground: 4 minutes
Path length: 3.0 miles (4.8 km)
Path width: 150 yards (137 m)
Deaths: 0
Injuries: 0
Property damage: $10,000
County: Eddy County
Touchdown point: 47.760, -98.760
Lift-off point: 47.759, -98.664
Record number: 1706091929-01

What the Weather Service recorded

During the day of June 9th, temperatures over eastern North Dakota and the northwest quarter of Minnesota topped out in the upper 70s along the Canadian border to lower 90s along the North Dakota/South Dakota border. Mid level temperatures were very warm over the central Dakotas, helping to suppress convective development until early evening. By that point, thunderstorms broke out over southern Manitoba down through central North Dakota, mainly along a cold front. These storms tracked east-southeast, mainly covering the Devils Lake region, down through the central Red River Valley, and into the Mahnomen to Hubbard county corridor. A mix of tornadoes, hail, and strong winds were reported.

This weak tornado crossed the southern end of Lake Washington, where a condensation plume was observed. Large branches were broken off of trees on either side of the lake, otherwise no significant damage was noted. Peak winds were estimated at 85 mph.

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

The warnings

13 minutes of warning. NWS FGF issued a tornado warning for this county at 01:16 UTC, 13 minutes before the tornado touched down, in force until 02:00 UTC.

The county was under a severe thunderstorm watch, issued at 22:00 UTC and running to 02:28 UTC.

Issued (UTC)	Expired	Product	Office
22:00 UTC	02:28 UTC	Severe Thunderstorm Watch	FGF
01:16 UTC	02:00 UTC	Tornado Warning	FGF
01:38 UTC	02:07 UTC	Severe Thunderstorm Warning	FGF
10:40 UTC	11:19 UTC	Severe Thunderstorm Warning	FGF

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 forecast that day

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 01:01 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.

What forecasters said that day

The local office's own words before the tornado touched down, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Grand Forks, ND wrote its last area forecast discussion before the tornado touched down at Jun 9, 7:00 PM CDT, 1 hour 29 minutes earlier.

Area forecast discussion, Jun 9, 7:00 PM CDT, 1 hour 29 minutes before

Area Forecast Discussion
National Weather Service Grand Forks ND
700 PM CDT Fri Jun 9 2017

.UPDATE...
Issued at 658 PM CDT Fri Jun 9 2017

No changes other than tweeks to current wx. Severe weather threat
continues in watch box...several right movers...one in Cavalier
county and watching severe storms from Rugby area move east.

&&

.SHORT TERM...(This evening through Saturday)
Issued at 321 PM CDT Fri Jun 9 2017

Severe thunderstorm chances tonight will be the main challenge
for the period.

Water vapor loop shows upper ridging into the Northern Plains,
starting to transition over to southwesterly flow aloft as a large
trough digs into the Pacific Northwest. Main shortwave with the
upper trough is lifting north into Canada, but sat loops show
signs of another weaker shortwave lifting northeastward from WY.
Surface low pressure is centered over western ND, with some
cumulus starting to get going on the east side of it along the
Missouri Valley. So far the SPC mesoanalysis page shows surface
and mixed layer instability to still be well capped, with some
elevated showers and storms moving across our northern counties
and southern Canada. Think the cap will start to dissipate in the
next few hours, and CAMs show some stronger storms developing
across north central ND near the Canadian border around the 23 to
00Z time frame. Still some variation as to how far south these
storms build, but with the strong cap think that most of the early
activity will be along and north of highway 2. Deep layer bulk
shear is around 40-50 kts, and with winds backing in the lower
levels some supercells will be possible with the first round of
convection. The SPC storm scale ensemble of opportunity has some
20-30 percent probabilities of over 100 m2/s2 updraft helicity, so
think rotating storms are probable. Dew point depressions are
rather high and LCL heights will not be super favorable for
tornadoes, but they cannot be completely ruled out and very large
hail will be possible.

After that first round moves east during the late evening, many of the
high resolution models bring a second round in from the west after
midnight with the cold front. Some of the models have pretty
strong cells arriving during the 08Z to 13Z time frame early
tomorrow morning, and there will still be around 2500 J/kg of MU
CAPE along with 40 to 50 kts of deep layer bulk shear. So a second
round of severe is possible late tonight into early morning. There
is still a lot of uncertainty as to where exactly the second round
will track, but highest shear and instability values are mostly
north of the I-94 corridor.

Tomorrow, after the second round of convection blows through there
will be a few lingering showers or storms mainly across the
north, but otherwise a bit more cool and quiet on the backside of
the surface trough axis. Temps will be knocked back a few degrees
but will still be fairly warm in the 80s to low 90s except in the
far north where more clouds and precip will be hanging around.

.LONG TERM...(Saturday night through Friday)
Issued at 321 PM CDT Fri Jun 9 2017

Sunday and Monday...Southwesterly flow aloft will keep things
fairly active across the region, but models are in pretty good
agreement on the next shortwave remaining mostly to our south over
SD into central MN. The southern counties could see some storms
from this shortwave late Saturday night into Sunday, but the best
instability will be well to our south. Will continue to keep high
chance POPs going but will leave out any mention of severe. Sunday
night should remain fairly quiet but another shortwave approaching
from the southwest late Monday could bring some precip over our
far south by late afternoon. Temperatures for the end of the
weekend and early next week will be near to slightly above
seasonal averages.

Tuesday through Friday...The active pattern will continue for at
least the first half of the upcoming week. Tue will feature an
upper low lurking over the Northern Rockies with the northern
plains in southwest flow sandwiched between this low and an upper
midwest ridge. At the surface, strong low pressure complex will
likely move right through the forecast area during the day Tue
with a warm and cold frontal boundary providing opportunities for
convective activity. Wed would feature more of a cold pool setup
as stacked system heads toward western Ontario. Thu and Fri have
the best chance for dry weather for most if not all of this time
frame.

The above average temperatures will continue on Tue and Wed before
dropping back into the more average 70s on Thu/Fri.

&&

.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 658 PM CDT Fri Jun 9 2017

VFR outside of thunderstorms where vsby/wind/cigs will be highly
variable.  Best risk of strong storms this eve  DVL, GFK.

&&

.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.
&&

UPDATE...Riddle
SHORT TERM...JR
LONG TERM...JR/WJB
AVIATION...Riddle

Hazardous weather outlook, Jun 9, 12:25 PM CDT, 8 hours 4 minutes before

Hazardous Weather Outlook
National Weather Service Grand Forks ND
1225 PM CDT Fri Jun 9 2017

MNZ001>009-013>017-022>024-027>032-040-NDZ006>008-014>016-024-
026>030-038-039-049-052>054-101300-
West Polk-Norman-Clay-Kittson-Roseau-Lake Of The Woods-
West Marshall-East Marshall-North Beltrami-Pennington-Red Lake-
East Polk-North Clearwater-South Beltrami-Mahnomen-
South Clearwater-Hubbard-West Becker-East Becker-Wilkin-
West Otter Tail-East Otter Tail-Wadena-Grant-Towner-Cavalier-
Pembina-Benson-Ramsey-Eastern Walsh County-Eddy-Nelson-
Grand Forks-Griggs-Steele-Traill-Barnes-Cass-Ransom-Sargent-
Richland-Western Walsh County-
1225 PM CDT Fri Jun 9 2017

This hazardous weather outlook is for portions of eastern North
Dakota, west central and northwest Minnesota.

.DAY ONE...This Afternoon and Tonight

Two rounds of severe storms are possible. The first round will be
this evening with scattered severe storms along and north of
highway 2. Significant hail greater than 2 inches is the main
threat, along with damaging wind up to 75 mph, an isolated
tornado, and excessive rainfall.

Round 2 is less certain, but confidence is increasing for activity
to move into eastern North Dakota sometime after 4am. The risk
area for this round is anywhere along and north of Interstate 94.
The main threat will be damaging winds, potentially greater than
75 mph.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday

Periods of thunderstorms are possible throughout this period. The
best chance for widespread convective activity and severe storms
is Monday night into Tuesday.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is expected this evening, and potentially again
during the early Saturday morning hours.

In the hours before

Local storm report, Jun 9, 7:43 PM CDT, 46 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE EASTERN ND/GRAND FORKS ND
743 PM CDT FRI JUN 09 2017

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0724 PM     TSTM WND GST     6 W CRYSTAL             48.60N 97.80W
06/09/2017  M94 MPH          PEMBINA            ND   MESONET

            PEAK WINDS MEASURED AT A PERSONAL WEATHER STATION.

&&

GGUST

Local storm report, Jun 9, 7:46 PM CDT, 43 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE EASTERN ND/GRAND FORKS ND
746 PM CDT FRI JUN 09 2017

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0745 PM     TSTM WND GST     1 S ST. THOMAS          48.61N 97.45W
06/09/2017  E70 MPH          PEMBINA            ND   TRAINED SPOTTER

            VERY STRONG WINDS AND VERY HEAVY RAIN WITH DIME TO NICKEL
            SIZED HAIL.

&&

GGUST

Local storm report, Jun 9, 8:01 PM CDT, 28 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE EASTERN ND/GRAND FORKS ND
801 PM CDT FRI JUN 09 2017

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0750 PM     HAIL             3 SW PENN               48.19N 99.13W
06/09/2017  E0.88 INCH       RAMSEY             ND   TRAINED SPOTTER

&&

BP

Local storm report, Jun 9, 8:04 PM CDT, 25 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE EASTERN ND/GRAND FORKS ND
804 PM CDT FRI JUN 09 2017

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0750 PM     HAIL             1 S ST. THOMAS          48.61N 97.45W
06/09/2017  E1.50 INCH       PEMBINA            ND   TRAINED SPOTTER

&&

GGUST

Local storm report, Jun 9, 8:05 PM CDT, 24 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE EASTERN ND/GRAND FORKS ND
805 PM CDT FRI JUN 09 2017

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0740 PM     TSTM WND GST     2 WSW ST. THOMAS        48.61N 97.49W
06/09/2017  M64 MPH          PEMBINA            ND   MESONET

            PEEAK WINDS MEASURED AT THE ST. THOMAS NDAWN STATION.

&&

GGUST

Local storm report, Jun 9, 8:23 PM CDT, 6 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE EASTERN ND/GRAND FORKS ND
823 PM CDT FRI JUN 09 2017

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0813 PM     HAIL             DEVILS LAKE             48.11N 98.87W
06/09/2017  E0.75 INCH       RAMSEY             ND   911 CALL CENTER

&&

BP

The air that afternoon

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.

Bismarck Municip, ND (KBIS), 00:00Z

1.5 hours before the tornado, 186 km from the path. June 10, 2017.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed. The warm shading is its CAPE, the cool shading the inhibition it has to break through.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km. RM and LM are the right and left moving storms Bunkers' method gives; the shaded area is the 0 to 1 km storm-relative helicity.

Mixed-layer CAPE: 1523 J/kg
Mixed-layer CIN: -25 J/kg
Surface CAPE: 1118 J/kg
Mixed-layer LCL: 2862 m above ground
0-6 km bulk shear: 30 kt
0-1 km bulk shear: 8 kt
0-1 km storm-relative helicity: 29 m²/s²
0-3 km storm-relative helicity: 62 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.7
0-3 km lapse rate: 9.3 K/km

Open this sounding in Storm Lab

Bismarck Municip, ND (KBIS), 12:00Z

10.5 hours after it, 186 km from the path. June 10, 2017.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed. The warm shading is its CAPE, the cool shading the inhibition it has to break through.

Hodograph

Mixed-layer CAPE: 0 J/kg
Mixed-layer CIN: -79687 J/kg
Surface CAPE: 0 J/kg
Mixed-layer LCL: 1347 m above ground
0-6 km bulk shear: 55 kt
0-1 km bulk shear: 22 kt
0-1 km storm-relative helicity: -167 m²/s²
0-3 km storm-relative helicity: 649 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0
0-3 km lapse rate: 4.1 K/km

Open this sounding in Storm Lab

The surface observations

Devils_lake (DVL), 42 km from the path, in the two hours either side.

Time (UTC)	Temp (°F)	Dew point (°F)	Wind	Gust (kt)	Pressure (mb)	Weather
23:30 UTC			120° 17 kt		994.9
23:35 UTC			120° 18 kt		994.6
23:40 UTC			120° 19 kt		994.2
23:45 UTC			120° 19 kt		994.2
23:50 UTC			120° 18 kt		993.9
23:55 UTC			110° 19 kt		993.9
23:56 UTC	81	60	110° 19 kt	23	993.9
00:00 UTC			110° 18 kt		993.9
00:05 UTC			100° 14 kt	20	993.9
00:10 UTC			90° 13 kt		993.9
00:15 UTC			100° 13 kt	18	993.9
00:20 UTC			100° 13 kt		993.6
00:24 UTC	80.6	59	90° 14 kt		993.2	VCTS
00:25 UTC			90° 13 kt		993.2
00:30 UTC			100° 14 kt		992.9
00:35 UTC			100° 12 kt
00:40 UTC			110° 11 kt	19		-RA
00:45 UTC			90° 14 kt			RA
00:50 UTC			80° 8 kt		993.2	-RA
00:55 UTC			60° 12 kt			RA
00:56 UTC	76	62	60° 13 kt		992.6	TSRA
01:00 UTC			40° 13 kt			-RA
01:05 UTC			30° 16 kt		993.6	-RA
01:10 UTC					995.9
01:14 UTC	69.8	62.6	320° 19 kt	41	997	-TSRA
01:15 UTC				29	996.3	-RA
01:20 UTC					994.9	-RA
01:25 UTC					995.6	-RA
01:30 UTC			40° 13 kt		995.6	-RA
01:34 UTC	68	62.6	50° 17 kt	31	995.3	VCTS -RA
01:35 UTC			50° 18 kt		995.6
01:40 UTC					995.3
01:45 UTC					994.9
01:50 UTC			50° 19 kt		995.3
01:55 UTC			50° 17 kt		995.3
01:56 UTC	67	62	50° 18 kt	24	995.3	VCTS
02:00 UTC			50° 17 kt		995.3
02:05 UTC			60° 15 kt	20	994.9
02:07 UTC	68	62.6	60° 18 kt	23	994.9
02:10 UTC			60° 15 kt		994.9
02:15 UTC			70° 19 kt	27	994.6
02:20 UTC			70° 19 kt		994.6
02:30 UTC			60° 18 kt		994.2
02:40 UTC			70° 21 kt		994.2
02:45 UTC			70° 19 kt		994.2
02:50 UTC			70° 21 kt		994.2
02:55 UTC			70° 18 kt		994.2
02:56 UTC	67	61	70° 19 kt	28	994.2
03:00 UTC			60° 18 kt		994.2
03:05 UTC			70° 21 kt		994.2
03:10 UTC			70° 21 kt		994.2
03:15 UTC			70° 16 kt		994.2
03:20 UTC			70° 18 kt		994.2
03:25 UTC			70° 19 kt		994.2

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

The radar

The Fargo/Grand Forks radar (KMVX), 107 km away, was scanning. The volume nearest the touchdown began at 01:29 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.

What was reported nearby

Local storm reports within 60 km of the path, in the three hours either side.

Time (UTC)	Report	Where	County	Remark
00:34 UTC	TORNADO 0	3 S Brinsmade	Benson, ND	A TORNADO TRACKED EASTWARD OVER LARGELY OPEN COUNTRY FOR NEARLY 2 MILES TO AROUND 4 NNW OF MINNEWAUKAN BY AROUND 737 PM CDT. THE GROUND SWIRL OF THIS TORNADO WAS VIDEOED BY STORM CHASERS NEAR THE WEST BAY OF DEVILS LAKE
00:50 UTC	HAIL 0.88	3 Sw Penn	Ramsey, ND
01:00 UTC	HAIL 1.75	2 W Carrington	Foster, ND	HAIL STORM LASTED FOR ABOUT 6 MINUTES.
01:05 UTC	HAIL 1.75	Carrington	Foster, ND
01:05 UTC	HAIL 1.75	Carrington	Foster, ND	A LOT OF GOLFBALL TO PING PONG BALL SIZED HAIL WITH GOLFBALL BEING THE LARGEST.
01:10 UTC	HAIL 1.5	Carrington	Foster, ND	PICTURE POSTED ON FACEBOOK. EVENT TIME WAS CORRECTED FROM 8:35 PM TO 8:10 PM.
01:13 UTC	HAIL 0.75	Devils Lake	Ramsey, ND
01:27 UTC	TORNADO	5 E Devils Lake	Ramsey, ND	TOUCHDOWN NOTED BY OBSERVER NEAR VINING OIL...LOOKING NORTH.
01:28 UTC	TSTM WND GST 66	2 S Devils Lake	Ramsey, ND	DVL RWIS
01:29 UTC	TSTM WND GST 58	1 E Crary	Ramsey, ND	PEAK WINDS MEASURED AT THE CRARY NDAWN STATION.
01:29 UTC	TORNADO 0	7 Ssw Warwick	Eddy, ND	A WEAK TORNADO TRACK TO EAST FOR NEARLY 3 MILES ACROSS FAR SOUTHERN EDDY TOWNSHIP ENDING ABOUT 7 SW OF HAMAR BY 833 PM CDT. THIS TORNADO CROSS THE SOUTHERN END ON LAKE WASHINGTON WHERE A CONDENSATION PLUME WAS ONSERVED.
01:31 UTC	TSTM WND GST 59	1 E Crary	Ramsey, ND	PEAK WINDS MEASURED AT THE CRARY NDAWN STATION.
01:35 UTC	HAIL 1.5	Carrington	Foster, ND	PICTURE POSTED ON FACEBOOK.
01:35 UTC	HAIL 1.5	2 S Hamar	Eddy, ND
01:40 UTC	HAIL 1	2 Nw Tolna	Nelson, ND	DIME TO QUARTER SIZED HAIL COVERED THE GROUND.
01:40 UTC	HAIL 1.75	3 Sw Brocket	Nelson, ND	LOTS OF QUARTER TO GOLF BALL SIZED HAIL.
01:50 UTC	TSTM WND DMG	5 Se Stephen	Benson, ND	NUMEROUS TREE BRANCHES DOWN, ONE LARGE TREE UPROOTED
02:01 UTC	HAIL 1	Courtenay	Stutsman, ND	LATE REPORT FROM FRIDAY EVENING.
02:34 UTC	HAIL 1.5	Cooperstown	Griggs, ND	HAILED FROM 934 TO 949 PM

From the Iowa Environmental Mesonet's archive of National Weather Service local storm reports.

This ground now

The live radar over the track Every 2017 tornado in North Dakota Every tornado in North Dakota since 1950 Warnings in force in North Dakota now The forecast where you are

The other tornadoes of June 9, 2017

9 more were confirmed in the United States that day.

Date	Time	Rating	Where	Path (mi)	Width (yd)	Damage
June 9	4:05 PM CDT	EF0	Will, IL	0.2	20
June 9	6:09 PM CDT	EF0	Cavalier, ND	2.0	200
June 9	6:27 PM CDT	EF1	Cavalier, ND	1.3	600	$100,000
June 9	6:45 PM CDT	EF2	Cavalier, ND	18.0	800	$1.5 million
June 9	7:08 PM CDT	EF2	Benson, ND	8.0	600	$200,000
June 9	7:12 PM CDT	EF1	Pembina, ND	1.0	200	$200,000
June 9	7:34 PM CDT	EF0	Benson, ND	2.0	200
June 9	8:27 PM CDT	EF0	Ramsey, ND	0.1	25
June 9	9:32 PM CDT	EF0	Griggs, ND	0.1	75

What this means

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.

Sources

NOAA Storm Prediction Center tornado database, 1950-2025, the official record kept by NOAA's Storm Prediction Center.