Colorado, 1997Flash Flooding and Hail in Colorado, August 11, 1997
August 11, 1997 · NWS BOU · 6 events in 4 counties and zones
3 hail, 2 flash flood, 1 lightning, as filed by the National Weather Service.
Every event with a place to put it; 3 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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- Deaths
- 0
- Injuries
- 1
- Property damage
- $128 million
- Crop damage
- None recorded
- Events
- 6
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.
Event by event
3 hail, 2 flash flood, 1 lightning. Local standard time, as filed.
Flash Flood, Jefferson
- When
- August 11, 2:30 PM MST to 3:15 PM MST
- Where
- Jefferson County, Lakewood
- Measured
- 75
- Property damage
- $128 million
- Coordinates
- 39.586, -105.250 (the zone’s center; the record gives no point)
Large hail, strong winds and torrential rain hammered portions of Lakewood and South Denver. Nearly 1 inch of rain fell in the span of 10 minutes in South Denver with a storm total of 1.81 inches reported. Street flooding was extensive as gutters and other drainage systems in the area were clogged by hail, piled several inches deep, as well as other debris. In addition, extensive damage to cars, homes and businesses was reported as strong thunderstorm winds to 50 mph and large hail accompanied the heavy rain. Several trees were downed by the strong winds and trees stripped of their leaves by the hail. A water lily exhibition on display at the Denver Botanic Gardens was heavily damaged. Final estimates of the damage included $60 million to automobiles with another $68 million to homes and businesses.
Hail, Jefferson
- When
- August 11, 2:32 PM MST
- Where
- Jefferson County, Lakewood
- Measured
- 0.75 in hail
- Coordinates
- 39.730, -105.100
Hail, Denver
- When
- August 11, 2:40 PM MST
- Where
- Denver County, South Denver
- Measured
- 1.5 in hail
- Coordinates
- 39.680, -104.970
Hail, Jefferson
- When
- August 11, 2:42 PM MST
- Where
- Jefferson County, Lakewood
- Measured
- 1 in hail
- Coordinates
- 39.730, -105.100
Lightning, Adams
- When
- August 11, 3:00 PM MST
- Where
- Adams County, Aurora
- Injuries
- 1 direct, 0 indirect
- Property damage
- $1,000
- Coordinates
- 39.874, -104.338 (the zone’s center; the record gives no point)
A man received minor injuries when he was struck by lightning while talking on the telephone.
Flash Flood, Arapahoe
- When
- August 11, 3:30 PM MST to 4:34 PM MST
- Where
- Arapahoe County, 8 mi SW of Byers
- Coordinates
- 39.650, -104.339 (the zone’s center; the record gives no point)
Intense thunderstorm winds, accompanied by very heavy rain, damaged a barn and snapped several trees. In addition, flooding and flash flooding was reported along several county roads as 2.5 inches of rain fell in the area.
- 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.
- Lightning
- A lightning strike that killed, injured or caused damage.
After NWS Directive 10-1605, the rules offices file Storm Data by.
- Flood in Colorado, August 11, 1997$25 million · 1 event
- Lightning Strike in Florida, August 11, 19973 injured · $500 · 1 event
- Lightning Strike in Florida, August 11, 19971 injured · 1 event
- Lightning Strike in Florida, August 11, 19971 injured · 1 event
- Flash Flooding and Heavy Rain in Idaho, August 11, 19975 events
- Flash Flooding and Heavy Rain in Idaho, August 11, 19974 events
- Heavy Rain in Idaho, August 11, 19973 events
- Hail in Colorado, August 11, 19972 in hail · 2 events
- Hail in Colorado, August 11, 19971 in hail · 2 events
- Waterspout in Mississippi, August 11, 19971 event
- Waterspout in Florida, August 11, 19971 event
- Damaging Wind in Texas, August 11, 1997$3,000 · 1 event
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: 5614048, 5614045, 5614046, 5614047, 5614049, 5614140.