The Easy Guide Understanding Tornado Alerts

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The Easy Guide Understanding Tornado Alerts

Tornado touching down from colorful storm cloud

by Steve LaNore, Certified Broadcast Meteorologist

The Easy Guide Understanding Tornado Alerts

Tornado watches and tornado warnings help you make the best decisions before and during dangerous storms to protect lives and property. There’s one set of concerns when a tornado watch is issued and a much more urgent list of actions for a tornado warning. In this article, we’ll help you understand the differences and how to respond, whether under a tornado watch or tornado warning.

Tornado Watch vs. Tornado Warning

To make the most of these types of alerts, you need to start with the basics: understanding the difference between a tornado watch and a tornado warning.

What is a Tornado Watch?

Tornado watches are issued by the Storm Prediction Center (SPC) when it detects severe thunderstorms with the potential for tornadoes. It may be a beautiful sunny day when they are first issued — but probably won’t stay that way for long. Watches are usually issued for a six- to nine-hour period, may cover parts of more than one state and will always be given an expiration time.

Tornado watches tell you the estimated storm setup and intensity — for example, “a few tornadoes” or, in more extreme cases, “strong tornadoes.” Information on hail size, straight-line wind speeds and average storm motion will also be included. If a watch includes the phrase “PDS” (particularly dangerous situation), look out: There’s a high risk of larger tornadoes.

What is a Tornado Warning?

A tornado warning means a tornado is indicated on Doppler radar, has been spotted by eyewitnesses or both. This is serious business; lives are at stake. Tornado warnings are “storm-based,” using polygons to outline the warned area. The warning text will tell you where the tornado is, along with its speed and direction of movement. If you’re within the tornado-warning polygon, the storm is less than an hour away.

How to Prepare When Watches or Warnings are Issued

What to Do When a Tornado Watch is Issued
Tornado watches give you time to prepare for an incoming storm. So once one is issued, it is best to take the following actions.

Examine your surroundings and locate the best place to hide if a watch gets upgraded to a warning. Bathrooms are usually a good choice in public places like restaurants, and there’s no harm in asking an employee where to go during a tornado warning.
Frequently check your mobile weather app, National Weather Service (NWS) website or TV weather source to track developing tornado threats.
If you have travel plans, map them out against the predicted storm path and re-route or postpone your trip if necessary.
Stock your home with the survival supplies that you need to weather out any incoming storms.

What to Do When a Tornado Warning is Issued
A tornado warning is a call to immediate action, and much more serious than a tornado watch. Here’s what to do:

Take cover in your safe place when a tornado warning is issued.
Remain in place until the storms pass or until all warnings are canceled for your location.

Stay Weather-Aware -Even Before Storms Show up

The best way to be prepared in the event of a watch or warning is to monitor the situation from credible weather sources like your local TV station, your local NWS office, a mobile app or the SPC website. Checking these regularly will keep you from getting blindsided when rough weather shows up. If you live in tornado-prone areas this is essential, but remember, tornadoes can happen any month of the year and not just in Tornado Alley.

Home Weather Monitoring System

A home weather station can also help you stay ahead of changing local conditions. To ensure you have the most accurate representation of developing storms in your area, invest in a system like the AcuRite Atlas™. It is engineered to give you the information you need to monitor a storm’s progress. It is rugged, dependable and equipped to monitor the following:

Pressure Drops. Surface pressures fall as severe weather approaches because intense updrafts within storms cause a decrease in the downward force of air. A barometer can track this change; a sudden drop in the indicated reading is cause for concern.
Inflow Winds. Large, violent thunderstorms have huge updrafts that suck in surrounding air. This strong wind is called inflow. An anemometer can monitor trends of increasing inflow; a sudden increase of storm inflow wind is another sign of danger.
Heavy Rainfall. AcuRite weather stations that monitor rainfall all contain a wireless electronic rain gauge which continuously empties, so there is no need to go outside and get soaking wet to check. Flash flooding often occurs many miles away from the NWS reporting station, and a rain gauge helps you figure out whether it’s just raining cats and dogs or if you’re facing more sinister waters ahead.