Flash floods are sudden, violent events that pose a significant weather-related threat to human life. The speed and power of this phenomenon demand immediate action from anyone in the threatened area. A Flash Flood Warning is not a suggestion for caution; it represents the highest alert level, indicating a life-threatening situation is either already in progress or is imminent.
Understanding the Alert Levels
The National Weather Service (NWS) issues two primary alerts to communicate the risk of flash flooding. A Flash Flood Watch means that conditions are favorable for flash flooding to develop in or near the designated area. This alert is a preparatory signal, indicating that heavy rainfall or factors like saturated soil are present, making the rapid onset of flooding possible.
A Flash Flood Warning, however, signifies a far greater level of danger because it means that flash flooding is already occurring or will happen very soon. The NWS issues this warning based on real-time observations, such as reports from law enforcement or radar showing intense rainfall rates. This immediate threat to life and property requires residents to take protective action without delay.
The Immediate Danger: Why Flash Floods Kill
Flash floods combine the destructive power of water with extreme speed and little warning time. Unlike general river flooding, flash floods can develop within minutes to a few hours, often catching people off guard. The water moves with tremendous force, which is a function of its velocity and depth.
This fast-moving water can reach heights of 10 to 20 feet and is capable of rolling boulders, tearing out trees, and destroying bridges. Just six inches of swiftly moving water is enough to knock an adult off their feet, making drowning the leading cause of death during these events.
The danger to drivers is severe: only one foot of moving water is enough to float many vehicles, and two feet can sweep away most cars, including SUVs and trucks. The water’s force can also carry debris, such as lumber, glass, and vehicles, which acts as a battering ram. Floodwaters hide hazards like washed-out roadbeds and can contain electrical current from downed power lines.
Essential Safety Measures When a Warning is Issued
The moment a Flash Flood Warning is issued, move immediately to higher ground. If you are in a location prone to flooding, such as a basement, low-lying area, canyon, or wash, you must evacuate vertically or horizontally to safety. Moving to the highest floor of a multi-story building is preferable to staying on the ground level, but avoid closed attics where you could become trapped.
Never attempt to drive or walk through floodwaters, a warning summarized by the National Weather Service’s slogan, “Turn Around, Don’t Drown.” If your car stalls in rapidly rising water, abandon it and seek higher ground immediately, as the vehicle can be swept away quickly.
If you are at home, preparedness is key.
Home Safety and Preparedness
- Have a pre-assembled emergency kit containing non-perishable food, water, medications, and a first-aid kit ready.
- Establish a communication plan so family members know how to contact one another if separated.
- Avoid entering basements or any room where water covers electrical outlets or where cords are submerged to prevent electrocution.
- Use a NOAA Weather Radio or local alerting systems to monitor the evolving situation and heed all instructions from public safety officials.
- Be aware that floodwaters may contain contaminants like sewage and hazardous chemicals, so avoid contact.
- If you must evacuate, take only essential items and follow designated evacuation routes before access is cut off.