History of Tornado warning in Timeline

A tornado warning is issued by weather agencies when a tornado is imminent or occurring, or when a severe thunderstorm capable of producing a tornado is detected. The warning advises people in the affected area to seek immediate shelter. These warnings are issued based on Doppler radar detecting rotation within a thunderstorm or from visual confirmation of a tornado, funnel cloud, or wall cloud reported by weather spotters, the public, law enforcement, or emergency management. Ground truth reports are especially important when radar data is unavailable or limited, such as in areas with gaps in radar coverage.

April 1908: U.S. Weather Bureau Addresses Tornado Protection

In April 1908, the U.S. Weather Bureau released several responses to a question posed about how to protect against tornadoes.

March 1925: Tri-State Tornado Devastation

In March 1925, the Tri-State Tornado, the deadliest in U.S. history, caused a very high death toll due to the lack of warnings, increasing the number of tornado-related fatalities through the 1950s.

1925: Tornado Death Rate

In 1925, the tornado death rate in the United States was 1.8 deaths per million people per year.

1938: Weather Bureau Rescinds Tornado Word Ban

In 1938, the Weather Bureau rescinded its prohibition on using the word "tornado" in weather products distributed to emergency management personnel.

April 1947: Deadly Glazier-Higgins-Woodward Tornadoes

In April 1947, the Glazier–Higgins–Woodward tornadoes resulted in death tolls well over 100, highlighting the lack of warnings and contributing to a steady increase in tornado-related fatalities through the 1950s.

March 20, 1948: Tornado Damages Tinker Air Force Base

On March 20, 1948, a tornado struck Tinker Air Force Base after a forecast by Miller erroneously predicted dry conditions. The tornado caused an estimated $10 million in damage to military aircraft.

March 25, 1948: First Official Tornado Forecast

On March 25, 1948, the first official tornado forecast was made by United States Air Force Capt. Robert C. Miller and Major Ernest Fawbush.

1948: Pioneering of Tornado Warnings by USAF

In 1948, the USAF pioneered tornado forecasting and warnings which restarted a debate over their reliability and whether military or civilian agencies should have jurisdiction over the issuance of weather warnings.

March 25, 1949: Successful Tornado Forecast by Miller and Fawbush

On March 25, 1949, Miller and Fawbush issued another tornado forecast, successfully predicting tornadic activity in southeastern Oklahoma.

July 12, 1950: Tornado Warning Ban Lifted

On July 12, 1950, the Weather Bureau Chief Francis W. Reichelderfer officially lifted the ban on issuing tornado warnings to the general public. He issued a Circular Letter to all first order stations advising that employees should avoid negating the Bureau's willingness or ability to make tornado forecasts.

1951: Air Force Forms Severe Weather Warning Center

In 1951, the Air Force began issuing severe weather forecasts, relayed to Weather Bureau offices and emergency personnel, through the formation of the Severe Weather Warning Center (SWWC).

March 1952: Weather Bureau Issues First Experimental Public Tornado Forecast

In March 1952, the Weather Bureau issued its first experimental public tornado forecast. While the first forecast proved inaccurate, a forecast the following evening managed to predict an outbreak of tornadoes across most of the warned seven-state area.

1954: First Televised Tornado Warning

In 1954, meteorologist Harry Volkman broadcast the first televised tornado warning over WKY-TV (now KFOR-TV) in Oklahoma City, believing that the ban on tornado warnings over broadcast media cost lives.

1974: Last tornado alert officially issued

Following the 1974 Super Outbreak, the last tornado alert to be officially issued was discussed in earnest. Doppler weather radar's ability to detect funnel cloud formations earlier than spotters and the public made tornado alerts largely obsolete, reducing false positives and public confusion.

1974: Average Tornado Warning Times

In 1974, average tornado warning times were between -10 to -15 minutes.

1974: Tornado Alert advisory in use

Until the early 1980s, the National Weather Service used a tornado alert advisory to indicate imminent tornado formation. These alerts covered situations like visible rotation in clouds. Use of this advisory declined after 1974.

May 3, 1999: First Tornado Emergency declared

On May 3, 1999, the first tornado emergency was declared when an F5 tornado struck southern portions of the Oklahoma City metropolitan area, causing major damage exceeding $1 billion.

2000: Decline in Tornado Death Rate

By 2000, the tornado death rate in the United States had declined to 0.11 per million people per year, largely credited to improvements in the tornado warning system.

September 20, 2002: Tornado Emergency declared in Indianapolis

On September 20, 2002, a tornado emergency was declared within the initial issuance of the tornado warning for an F3 tornado that struck the Indianapolis, Indiana metropolitan area.

October 2007: National Weather Service Issues Warnings

Prior to October 2007, the National Weather Service issued warnings on a per-county basis.

2008: Emergency Management Ontario implements red alerts

In 2008, Emergency Management Ontario implemented a system issuing red alerts for sections of the province under an Environment Canada-issued tornado warning. The system can sometimes override the tornado warning if local government or media outlets participate in the program.

March 2012: NWS Implements Impact Based Warning System

In March 2012, as part of its implementation of a multi-tier Impact Based Warning (IBW) system, the NWS Weather Forecast Offices began incorporating categorical tornado and damage threat indicators.

March 2013: Expansion of Threat and Damage Indicators

In March 2013, the NWS expanded the threat and damage indicators to 33 additional Central Region WFOs.

2013: Increased Tornado Warning Times

As of 2013, the average tornado warning times had increased to about 15 minutes.

March 2014: Further Expansion of IBW Indicators

In March 2014, eight additional offices operating within the Eastern, Southern and Western Region divisions began using the IBW indicators.

2016: Agency-Wide Use of IBW Format

In 2016, the entire agency began using the Impact Based Warning (IBW) format for tornado warnings.

August 15, 2020: First Tornado Warning for Pyrocumulonimbus

On August 15, 2020, the National Weather Service issued its first-ever tornado warning for a pyrocumulonimbus cloud capable of producing a tornado in southeastern Lassen County, California, during the Loyalton Fire.

July 2021: Full Implementation of IBW Formatting

In July 2021, Impact Based Warning (IBW) formatting was fully implemented for all individual warning bulletins when all NWS offices incorporated damage threat indicators into severe thunderstorm warnings.

April 2023: Introduction of TORNADO Act

In April 2023, U.S. Sen. Roger Wicker introduced the Tornado Observation Research Notification and Deployment to Operations (TORNADO) Act to improve NOAA's severe weather prediction and alert communication methods.