Public Works

Flood 101

You can’t see what is happening under water on the roadway.

Maybe there is solid ground, but maybe not.

Photo courtesy Patsy Lynch
FEMA photos

FloodRoadDamagPhoto-Patsy Lynch

A flash flood doesn't call ahead and let you know its coming. You need to protect yourself by tracking the weather and being alert to danger. Check the weather forecast before you engage in outdoor activities.

Flash floods occur when heavy rain falls in an area. When forecasters predict storms, stay away from streams, ditches, and gullies. A storm upstream from you could send water rushing down your way.

If the sky looks stormy, check the television, radio, or internet for weather updates.

Forecasters issue a watch when they think you should watch out for storm problems, an advisory when smaller problems begin to occur, like minor street flooding and a warning is issued when the storms are actually causing larger, dangerous problems like flash flooding.

Weather Watch

Looks like the storm could cause problems like flooding - Things might turn bad.

Weather Advisory

Small problems happens because of a storm, like small amounts of flooding - Some problems have started.

Weather Warning

When there are big problems from a storm like flash flooding. - Situation has turned dangerous.

Flash Flood Warning Safety Precautions

If a flash flood warning has been issued, act immediately! You may only have seconds before flood waters appear. Read though the list of flood safety rules below. If you follow them during a flood warning, you will keep yourself out of danger.

  1. If you are outdoors and a flash flood is likely, get to higher ground immediately.
  2. Get out of places that are likely to flood, like canyons, ditches, and dry stream beds.
  3. Avoid already flooded areas. Never attempt to cross running flood water.  
  4. If you are in a car during a flood, never drive through flooded roadways. The roadway could be damaged; the roadway might be gone. Don’t drive your car where you can’t see the roadway.  You can’t see what is under that water. The roadway could be gone.  Fact:  Nearly half of all flashflood deaths are auto related.  Turn Around Don’t Drown
  5. If you car stalls, leave it immediately and get to higher ground.  Fact: If your car stalls in just two feet of moving water, the water will have enough force to lift up your car and carry it away. Imagine what would happen to a person trying to walk through that same water.
  6. Be especially careful at night when it's harder to see flood dangers.

Our southwestern desert is especially dangerous for both hikers and vehicles from the sudden onslaught of water from isolated thunderstorms. A moving flood will usually be headed by a debris pile that may have wood branches and/or logs. Deep slot canyons can be especially dangerous to hikers as they may be flooded by a storm that occurs on a mesa miles away, sweeping through the canyon, making it difficult to climb up and out of the way to avoid the flood.