What does a flash flood emergency signify and how can this alert save lives?

At a Glance

• Highest-level NWS alert for flash floods
• Issued for imminent, severe threat to life and potential catastrophic damage
• Over 24 alerts in 2023, including California snowmelt, Ft. Lauderdale flood, and Vermont severe flooding.

A flash flood emergency is an uncommon alert issued by the National Weather Service that not only demands your attention but also signifies that you are likely facing imminent danger.

Firstly, what constitutes a flash flood warning? You may be familiar with flash flood warnings, which the NWS issues when flash flooding is either ongoing or expected to occur soon. According to the Iowa Environmental Mesonet, the NWS issued almost 3,700 of these warnings in 2023.

Typically, areas under a flash flood warning will experience flooding on at least some streets and roads, posing a hazard to drivers. Some of these warnings encompass situations where a few low-lying properties have been affected by water.

However, a more severe flash flood alert exists. In response to the substantial volume of flash flood warnings issued, just over two decades ago, the NWS introduced an even graver alert known as a flash flood emergency. This alert is reserved for rare instances when there is a significant threat to life or the potential for catastrophic damage.

When activated, these flash flood emergencies are incorporated into existing flash flood warnings, standing out as a prominent headline near the top of the warning.

Understanding “Emergency” in Flash Flood Alerts

According to NWS guidelines, circumstances that may prompt a flash flood emergency include:

• Confirmation by local or state emergency managers of rapidly rising water posing a life-threatening situation.
• Anticipation or occurrence of rapid water rise to levels endangering typically safe locations, necessitating rescue and risking entire homes.
• Deployment of numerous swift-water rescue teams to an unusually severe flash flood.
• River and stream gauges indicating water levels reaching major or rarely seen flood stages.
• Complete failure of a large, high-hazard dam with potential catastrophic impact downstream.

This concept is akin to tornado emergencies, issued when there’s an imminent or ongoing confirmed tornado with severe threats to life and catastrophic damage.

Actions during a Flash Flood Emergency

If faced with a flash flood emergency:

• Immediately move to higher ground.
• Refrain from travel unless escaping a flooded area or evacuating as directed by local officials.
• Avoid walking or driving through floodwaters, as depth may be deceptive, and the road underneath could be compromised. Even slow-moving water can pose significant dangers, potentially sweeping you off your feet or carrying away your vehicle downstream.

This highest-level flash flood alert triggers a loud smartphone alarm through a wireless emergency alert.

Frequency of Flash Flood Emergencies

According to the Iowa Environmental Mesonet, the rarity of these emergencies is evident. In 2023, a mere 29 flash flood emergencies were issued nationwide, constituting less than 1 percent of all NWS flash flood alerts.

Recent Flash Flood Emergency Events in 2023

In 2023, several life-threatening flash flood emergencies unfolded:

• Mid-March, Kernville, California: Heavy rain on the extensive southern Sierra snowpack led to a flash flood emergency, marking one of the destructive flood events in California from December 2022 through spring.
• April, Ft. Lauderdale, Florida: Historic flash flooding ensued with over 20 inches of rain in less than 24 hours, causing widespread damage.
• Mid-July, New York’s Lower Hudson Valley and Vermont: Torrential rain triggered multiple flash flood emergencies, resulting in washed-out roads and inundated homes.

These events each incurred at least $1 billion in damages, according to NOAA estimates. Additionally, smaller-scale flash flood emergencies occurred in Leominster, Massachusetts, on Sept. 11, and Georgetown, South Carolina, on Dec. 17, leading to widespread road flooding, stranded vehicles, and flooded homes.

Flash Flood Emergencies: Immediate, Life-Saving Action Required

Flash flood emergencies signify destructive, life-threatening events. If one is issued for your area, respond urgently, mirroring the swift action taken for a tornado warning. Your prompt response could be the crucial factor in saving your life.