Colorado, 1997

Tornadoes and Flash Flooding in Colorado, May 21 to 27, 1997

May 21 to 27, 1997 · NWS BOU · 21 events in 7 counties and zones

16 hail, 2 flash flood, 2 tornado, 1 thunderstorm wind, as filed by the National Weather Service.

Where it happened

Every event with a place to put it; 2 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.

  • Tornadoes
  • Tropical storms and surge
  • Floods
  • Wind
  • Hail
  • Winter weather
  • Heat and drought
  • Cold
  • Fire, smoke and dust
  • Marine and coastal
  • Other

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The toll

Deaths
0
Injuries
0
Property damage
$2.0 million
Crop damage
None recorded
Events
21

Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.

The radar

The national radar mosaic for the moment the first event began.

Open the radar archive at this moment

Event by event

16 hail, 2 flash flood, 2 tornado, 1 thunderstorm wind. Local standard time, as filed.

Thunderstorm Wind, Logan

When
May 21, 1:00 PM MST to 4:00 PM MST
Where
Logan County, Proctor
Measured
50 kt (58 mph)
Coordinates
40.800, -102.930

Strong thunderstorm winds blew the top off a corn receiving mill south of Proctor during the afternoon. Two of the corn receiving legs were blown down, toppling the top of the mill. The peak wind gust was estimated and the exact time of the incident was unknown.

Flash Flood, Arapahoe

When
May 21, 2:00 PM MST to 3:30 PM MST
Where
Arapahoe County, Deer Trail
Coordinates
39.650, -104.339 (the zone’s center; the record gives no point)

Heavy rain and small hail associated with a stationary line of thunderstorms developed over eastern Arapahoe County. Several basements were flooded in the town of Deer Trail as well as pastures and fields around town. Some streets and intersections in the downtown area were covered by 18 inches of standing water. A storm spotter located 2 miles northeast of Deer Trail recorded nearly 4 inches of rainfall in less than 2 hours.

Hail, Jefferson

When
May 23, 3:16 PM MST
Where
Jefferson County, Broomfield
Measured
0.75 in hail
Coordinates
39.900, -105.070

Hail, Weld

When
May 23, 3:56 PM MST
Where
Weld County, Tonville
Measured
0.75 in hail
Coordinates
40.020, -104.680

Hail, Weld

When
May 23, 4:25 PM MST to 4:35 PM MST
Where
Weld County, 10 mi SE of Roggen
Measured
0.75 in hail
Coordinates
40.070, -104.230

Hail, Boulder

When
May 24, 1:40 PM MST
Where
Boulder County, Broomfield
Measured
1 in hail
Coordinates
39.920, -105.070

Hail, Weld

When
May 24, 2:10 PM MST
Where
Weld County, Briggsdale
Measured
1 in hail
Coordinates
40.630, -104.320

Hail, Boulder

When
May 24, 4:35 PM MST
Where
Boulder County, Boulder
Measured
0.75 in hail
Coordinates
40.020, -105.270

Flash Flood, Weld

When
May 24, 6:30 PM MST to May 25, 1:30 AM MST
Where
Weld County, Grover
Coordinates
40.555, -104.392 (the zone’s center; the record gives no point)

Large hail and heavy rain damaged beet, corn and wheat crops throughout Weld County during the afternoon and into the evening hours. Spotters 21 and 23 miles north of New Raymer reported hail up to 3 inches deep had blanketed the highways and ditches. Later in the evening, and into the early morning hours of the 25th, the town of Grover received up to 5 inches of rainfall as a series of thunderstorms trained over the area. Several roads east of the town were flooded and impassable. No estimates of the damage were available.

Hail, Weld

When
May 24, 7:10 PM MST
Where
Weld County, 21 mi N of New Raymer
Measured
1.5 in hail
Coordinates
40.830, -103.780

Hail, Weld

When
May 24, 7:12 PM MST
Where
Weld County, 23 mi N of New Raymer
Measured
1.25 in hail
Coordinates
40.870, -103.780

Hail, Boulder

When
May 25, 3:16 PM MST
Where
Boulder County, Broomfield
Measured
0.75 in hail
Coordinates
39.920, -105.070

Hail, Weld

When
May 25, 3:57 PM MST
Where
Weld County, 3 mi E of Lochbuie
Measured
0.75 in hail
Coordinates
40.020, -104.670

Tornado, Weld

When
May 25, 4:01 PM MST to 4:02 PM MST
Where
Weld County, 6 mi SW of Prospect
Rating
F0
Path length
0.1 mi
Path width
50 yd
Coordinates
39.980, -104.420

Hail, Weld

When
May 25, 4:30 PM MST
Where
Weld County, 10 mi E of Prospect
Measured
0.75 in hail
Coordinates
40.050, -104.150

Hail, Adams

When
May 25, 4:43 PM MST
Where
Adams County, 6 mi E of Watkins
Measured
1.75 in hail
Coordinates
39.750, -104.480

Hail, Adams

When
May 25, 5:05 PM MST
Where
Adams County, 6 mi W of Watkins
Measured
0.75 in hail
Coordinates
39.750, -104.720

Tornado, Morgan

When
May 27, 1:15 PM MST to 1:16 PM MST
Where
Morgan County, 3 mi NW of Ft Morgan
Rating
F0
Path length
0.1 mi
Path width
50 yd
Coordinates
40.280, -103.830

Hail, Weld

When
May 27, 3:15 PM MST
Where
Weld County, 1 mi E of Greeley
Measured
1 in hail
Property damage
$2.0 million
Coordinates
40.420, -104.670

Hail, Weld

When
May 27, 3:15 PM MST
Where
Weld County, 3 mi E of Evans
Measured
1 in hail
Coordinates
40.380, -104.630

Hail, Weld

When
May 27, 3:15 PM MST
Where
Weld County, Eaton to Kersey
Measured
1 in hail
Coordinates
40.530, -104.700

Large hail caused $2.0 million in damage to several car dealerships in Greeley. Spotty crop damage was reported near Eaton, extending along the east side of Greeley to just east of Kersey. Three hundred acres of beets were destroyed.

What these are

Thunderstorm Wind
Winds from a thunderstorm of 50 knots (58 mph) or more, or lower winds that caused damage or casualties. Measured gusts are marked MG, estimated EG.
Flash Flood
Flooding that begins within six hours of the rain that causes it, or of a dam or levee failure or ice jam release, often with deadly speed.
Hail
Hail three-quarters of an inch or larger, or smaller hail that caused damage, filed with the largest stone measured.
Tornado
A violently rotating column of air in contact with the ground and extending from a thunderstorm, filed with its path, width and Fujita or Enhanced Fujita rating from the damage survey.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

More

Every storm in Colorado in 1997Every state in 1997This day in weather historyThe tornado archive for Colorado, 1997Warnings in Colorado, May 1997

Sources

NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 5599152, 5599151, 5599153, 5599154, 5599155, 5599156, 5599157, 5599158, 5599230, 5599159, 5599160, 5599231, 5599232, 5599233, 5599234, 5599235, 5599236, 5599237, 5599238, 5599239, 5599240.