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 urges people in the affected area to seek immediate shelter. Modern Doppler radar is crucial for detecting rotation within thunderstorms, enabling early warnings. Visual sightings of tornadoes, funnel clouds, or wall clouds reported by weather spotters, the public, law enforcement, or emergency management personnel also trigger warnings, particularly when radar coverage is limited. These ground-truth observations are critical, especially in areas with radar gaps, for ensuring public safety.

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 Ban on "Tornado" Usage

In 1938, the Weather Bureau rescinded its ban on using the word "tornado" in weather products disseminated to emergency management personnel, marking a shift in the bureau's approach to tornado warnings.

March 20, 1948: Tinker Air Force Base Tornado

On March 20, 1948, a tornado struck Tinker Air Force Base after an erroneous weather forecast, causing significant damage to military aircraft. The tornado was preceded by a warning sent from Will Rogers Airport, indicating a tornado moving northeast.

March 25, 1948: First Official Tornado Forecast and Warning

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

1948: Debate over Reliability of Forecasts

In 1948, the accuracy of Miller and Fawbush's tornado forecasts sparked debate over their reliability and the jurisdiction of weather warning issuance, highlighting the tension between military and civilian agencies in disseminating weather information.

March 25, 1949: Successful Tornado Prediction in Southeastern Oklahoma

On March 25, 1949, Miller and Fawbush successfully predicted tornadic activity would occur in southeastern Oklahoma, marking another significant milestone in tornado forecasting.

July 12, 1950: Ban on Tornado Warnings Lifted

On July 12, 1950, Chief of Bureau Francis W. Reichelderfer officially lifted the ban on issuing tornado warnings to the general public, allowing Weather Bureau employees to make tornado forecasts when a "good probability of verification" existed.

1951: Formation of the Severe Weather Warning Center

In 1951, the Air Force began issuing severe weather forecasts through the formation of the Severe Weather Warning Center, which relayed information to Weather Bureau offices and emergency personnel, later leading to conflict and criticism over public tornado warnings.

March 1952: First Experimental Public Tornado Forecast

In March 1952, the Weather Bureau issued its first experimental public tornado forecast, which proved inaccurate. However, a forecast the following evening predicted an outbreak of tornadoes across a seven-state area.

1954: First Televised Tornado Warning

In 1954, meteorologist Harry Volkman broadcast the first televised tornado warning over WKY-TV in Oklahoma City, interrupting regular programming to warn viewers of a reported tornado. This defied the FCC's ban on broadcasting tornado warnings.

1974: Decline in Use of Tornado Alert Advisory

After 1974, the National Weather Service began to decrease their use of an intermediate tornado advisory, called a tornado alert, which indicated imminent tornado formation.

1974: 1974 Super Outbreak

Following the 1974 Super Outbreak, the obsolescence of the tornado alert system due to Doppler weather radar was earnestly discussed. The radar's ability to detect funnel clouds earlier and reduce false positives led to less public confusion.

1974: Average Warning Time

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

May 3, 1999: First Tornado Emergency Declared

On May 3, 1999, the first tornado emergency was declared when an F5 tornado struck southern Oklahoma City, causing over $1 billion in damage. This event marked the use of an enhanced severe weather statement to indicate a catastrophic tornado risk.

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, a significant decrease from 1.8 deaths per million in 1925. This change is attributed to improvements in the tornado warning system.

September 20, 2002: Tornado Emergency Declared in Indianapolis

On September 20, 2002, a tornado emergency was declared during the initial tornado warning for an F3 tornado that struck the Indianapolis, Indiana metropolitan area. This highlights the use of tornado emergencies even for tornadoes of significant, but not the highest, intensity.

October 2007: NWS Issues Warnings on a Per-County Basis

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

2008: Implementation of Emergency Alert System

In 2008, Emergency Management Ontario implemented a system issuing red alerts for areas under a tornado warning issued by Environment Canada. This can include overriding tornado warnings if local governments or media outlets participate in the program.

March 2012: Implementation of Impact Based Warning (IBW) System

In March 2012, the NWS Weather Forecast Offices in Wichita, Topeka, Springfield, St. Louis, and Kansas City/Pleasant Hill began incorporating categorical tornado and damage threat indicators as part of a multi-tier Impact Based Warning (IBW) system.

March 2013: Expansion of Threat and Damage Indicators to Additional WFOs

In March 2013, the NWS expanded the threat and damage indicators to 33 additional Central Region Weather Forecast Offices (WFOs).

2013: Increased Average Warning Times

As of 2013, the average tornado warning times had increased to about 15 minutes, with some cases extending to more than an hour. This improvement is due to advances in technology and warning systems.

March 2014: Expansion of Threat and Damage Indicators

In March 2014, eight additional National Weather Service offices operating within the Eastern, Southern, and Western Region divisions began using the Impact Based Warning (IBW) indicators.

2016: Agency-Wide Adoption of IBW Format

In 2016, the entire National Weather Service 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, due to the Loyalton Fire.

July 2021: Full IBW Implementation

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

April 2023: Introduction of the TORNADO Act

In April 2023, U.S. Senator Roger Wicker introduced the Tornado Observation Research Notification and Deployment to Operations (TORNADO) Act to improve NOAA's methods for predicting severe weather events and communicating alerts.