Forecasting Tornadoes

Predicting One of Nature’s Most Violent Storms

Mesocyclone tornado.

Mesocyclone tornado.

High resolution (Credit: NOAA)

A tornado is a violently rotating column of air that descends from a thunderstorm. It’s one of nature’s most terrifying and destructive weather phenomena. They can destroy large buildings, lift 20-ton railroad cars from their tracks, and drive a blade of straw through a telephone pole. In a typical year, more than 1,200 tornadoes occur throughout the vast United States.

The most violent tornadoes are capable of tremendous destruction with wind speeds of 250 mph or more. Damage paths can be in excess of one mile wide and 50 miles long. Fortunately, the nation has the most sophisticated tornado forecasting system in the world, provided exclusively by NOAA’s National Weather Service.

Scientists in NOAA’s National Severe Storms Laboratory, in partnership with the National Weather Service, are dedicated to improving severe weather warnings and forecasts in order to save lives and reduce property damage. Severe weather research conducted at NSSL has led to substantial improvements in severe and hazardous weather forecasting resulting in increased warning lead times to the public.

NOAA National Weather Service meteorologists provide forecasts, watches and warnings to the public.

NOAA National Weather Service meteorologists provide forecasts, watches and warnings to the public.

High resolution (Credit: NOAA)

Forecasting Severe Weather

The National Weather Service's Storm Prediction Center issues general severe weather outlooks and watches. Warnings come from each of the 122 local NWS forecast offices.

The severe weather forecast process begins with the Convective Outlook. This tell you where you can expect both severe and non-severe thunderstorms to occur around the country.

Areas of possible severe thunderstorms are labeled slight, moderate, or high risk depending upon the coverage and intensity of expected storms in a region. These are issued for today, tomorrow, the day after tomorrow, and the rest of the week.  

As time progresses, a severe weather threat often becomes better defined over an area smaller than the Outlook, both in space and time. Mesoscale Discussions are often needed to describe an evolving severe weather threat.

Severe Thunderstorm and Tornado Watches: Be Alert

Tornadoes leave a path of death and destruction.

Tornadoes leave a path of death and destruction.

High resolution (Credit: NOAA)

If a severe thunderstorm appears imminent, or likely to occur in the next several hours, the NWS will issue a severe thunderstorm or tornado Watch.

A tornado watch defines an area where tornadoes and other kinds of severe weather are possible in the next several hours. At this time, you should be alert and prepared to go to safe shelter if a tornado develops or a warning is issued. Turn on local TV or radio, monitor NOAA weather radio, make sure you have ready access to safe shelter, and tell your friends and family about the potential for tornadoes in the area.

Warnings Mean Take Action Now!

Once a watch is issued, forecasters in the threat area closely monitor radar imagery and spotter reports to issue the appropriate severe thunderstorm and tornado warnings.

Doppler radar image of a severe storm.

Doppler radar image of a severe storm.

High resolution (Credit: NOAA)

When a tornado appears imminent, local NWS offices issue a tornado Warning, which means a tornado has been spotted or that Doppler radar indicates a thunderstorm circulation that can spawn a tornado. When a tornado warning is issued for your town or county, take immediate safety precautions.  

Pay Attention – Be Safe

One way to stay informed is with a NOAA Weather Radio All Hazards, a nationwide network of radio stations broadcasting continuous weather information directly from the nearest National Weather Service office. NWR broadcasts official Weather Service warnings, watches, forecasts and other hazard information 24 hours a day, seven days a week.

For more information about how to stay safe during severe weather, including tornadoes, visit NOAA’s Tornado Safety Tips, Severe Weather Safety, and That Weather Show podcasts. NOAA logo.