Flash Floods and Warnings

TODAYS TOPIC DURING THIS FLOOD SAFETY AND WILDFIRE AWARENESS WEEK IS FLASH FLOODS.

Colorado is more than familiar with flash flooding. Nearly 300 Coloradans have been killed by flash flooding since the year 1900. The Big Thompson Canyon flood of July 31, 1976 was Colorado's worst flash flood in terms of lives lost. That single event claimed 144 lives.

Flash Flood in Colorado History

1904 - One hundred people drowned when a railroad bridge just north of Pueblo failed and a passenger train plunged into Fountain Creek.

1997 - A flash flood in Fort Collins drowned 5 people and caused 200 million dollars of property damage.

2013 - Historic rainfall from September 11th to the 14th caused massive flash flooding near Boulder and Colorado Springs. Nine people drowned during the flooding, which was a combination of flash floods and river floods. These floods were much more extensive the the Big Thompson Canyon flood of 1976, but because of timely and accurate warnings, many people stayed out of harm's way and lives were saved.

What is a Flash Flood?

A flash flood is defined as a rapid rise in water levels, along rivers, creeks, normally dry washes, arroyos, or even normally dry land areas. Flash floods generally occur within 6 hours of the rainfall or other event that causes them. They frequently happen with little advance notice.

Flash floods frequently result from high rainfall rates, and infrequently result from dam failures, levee failures, or sudden breaks in river ice jams. Flash floods are very destructive due to the force of the moving water and the accompanying debris. This tremendous force can easily damage or destroy roadways, bridges, and buildings.

Flash Flooding and Wild Fires

In recent years, Colorado has seen major flooding and damage when rains have occurred on wildfire burn scar areas. Even moderate rainfall rates can cause significant flooding in the first few years after a forest fire. If you are in or near a burn scar area, you need to plan ahead and be aware of the weather. Rainfall upstream of you can cause a flash flood to come roaring down the mountain to where it is not raining.

What Can You Do?

Know where you are.
- If you live, work, drive, or hike along a river, creek, or arroyo, be aware of the weather.
Have a plan.
- You should know your flash flood risks, and make your plans to save your life and those around you.
- Be aware of general flash flood plans and procedures that have been developed and implemented by your local emergency management officials.

National Weather Service Actions

Hazardous Weather Outlooks are issued daily and will discuss flash flood potential.
A Flash Flood Watch is issued when conditions are more conducive to flooding than a normal day.
A Flash Flood Warning is issued when flooding is likely or is already occurring.

When a Flash Flood Warning is issued for your area, you need to act as quickly as possible. If you are in a drainage area or in other low spots, walk or climb to higher ground. Know your escape routes and act as quickly as possible. A short walk or climb to higher ground may just save your life.

Many flash flood deaths occur in vehicles. Do not drive through a flooded roadway. The water may be much deeper than you think, because the roadway may be damaged or washed away. One to two feet of water will carry away most vehicles. Instead:

Turn Around Don't Drown.

For more information on flood safety go to:

https://www.weather.gov/safety/flood