Weather 101: Know the difference – flash flood watch, warning, & emergency!

Weather 101

Watch = Prepare & Monitor, Warning = Takes Action!

Flash flooding is a year-round risk in NW Arkansas and the River Valley. While some areas are more prone to flash flooding than others, it is important to know what to do when different flash flood alerts are issued.

Flash Flood Watch

Example of a flash flood watch in southern Missouri on Tuesday, April 27, 2021.

Similar to a severe thunderstorm or tornado watch for their respective hazards, a flash flood watch means the ingredients are coming together over an area to produce flash flooding

A flash flood watch can vary greatly in size and duration. It can stretch from a couple of counties to an entire NWS office forecast region. Flash flood watches are issued from individual NWS forecast offices. However, neighboring offices can issue their own respective flash flood watch and cover an entire region of the country. This is typical for widespread heavy rain events (such as a hurricane or stalled out front that doesn’t move for days).

Flash Flood Warnings

A flash flood warning means a flash flood is imminent or occurring and you need to take action. Depending on how the flash flood is being detected or reported, the National Weather Service will issue various warning tags within the flash flood warning.

Radar-indicated flash flood tag

If a flash flood warning contains this tag, heavy rain has been detected by Doppler Radar and may lead to flash flooding.

Example of a radar-indicated flash flood warning near New York City, NY on Saturday, August 21, 2021.

Observed flash flood tag

If a flash flood is occurring and reported to the National Weather Service, an observed tag will be issued.

Example of an observed flash flood warning west of Nashville, TN on Saturday, August 21, 2021.

Considerable flash flood tag

If flash flooding occurs and the National Weather Service is receiving reports of water rescues and/or considerable damage in an area, they may issue a “considerable” tag. A considerable flash flood is more significant than a typical flash flood, but not necessarily as catastrophic as a flash flood emergency.

A fact sheet provided by the NWS states considerable tags are “used rarely when there are indications flash flooding capable of unusual severity or impact is imminent or ongoing and urgent action is needed to protect lives and property”.

Example of a considerable flash flood warning west of Nashville, TN on Saturday, August 21, 2021,

Flash flood emergency (catastrophic) tag

When the National Weather Service receives reports of several water rescues and significant damage to structures from a flash flood, the NWS may decide to issue a flash flood emergency.

Flash flood emergencies are used when the threat is considered “catastrophic” and are to “use exceedingly rare when a flash flood threat to life and catastrophic damage is occurring or is imminent, and floodwaters have risen or will rise to levels rarely if ever seen.”

Example of flash flood emergency outside of Nashville, TN on Saturday, August 21, 2021.

While there may be different kinds of flash flood warnings, they all have one thing in common. A flash flood is imminent or occurring. Never drive through floodwaters, always turn around and find another route. If you are in your home or business, go to the upper levels if water is coming inside.

DO NOT WALK THROUGH FLOODS UNLESS IT’S ABSOLUTELY NECESSARY! Floodwaters can carry all different types of debris, including cars, fences, and sharp objects that could lead to injury.

Of course, the best way to stay safe during a flash flood event is to be aware of when one is possible by staying up to date on the forecast.

For more information on the impact-based warnings for flash floods, check out the National Weather Service’s fact sheet below.

Certain Alerts Trigger WEA Alerts On Your Phone

In the past, the NWS would send all flash flood warnings over the wireless emergency alert (WEA) system. This has been changed so only flash flood warnings with the “considerable” or “catastrophic” tag will trigger the wireless emergency alert system.

Send Us Your Questions!

Send us your weather-related questions (weather@knwa.com) and we’ll answer them right here on Weather 101!

Copyright 2021 Nexstar Media Inc. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.

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