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 one is present. These warnings advise people in the affected area to seek immediate shelter. Modern technology, such as Doppler radar, helps detect 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, especially when radar data is limited or unavailable. These ground observations are critical, particularly in areas with gaps in radar coverage, helping to ensure timely warnings and public safety.

March 1925: Tri-State Tornado Devastation

In March 1925, the Tri-State Tornado, the deadliest in U.S. history, caused significant fatalities due to the lack of adequate warning systems.

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"

In 1938, the Weather Bureau reversed its policy and lifted the ban on using the term "tornado" in weather products intended for emergency management personnel, marking a shift in communication strategy.

April 1947: Deadly Tornadoes

In April 1947, deadly tornadoes, such as the Glazier–Higgins–Woodward tornadoes, occurred, further emphasizing the need for improved warning systems.

March 20, 1948: Tornado Strikes Tinker Air Force Base After Erroneous Forecast

On March 20, 1948, a tornado struck Tinker Air Force Base after an erroneous forecast of dry conditions. The forecasters at Will Rogers Airport sent a warning to Tinker that the storm encroaching the city was producing wind gusts of 92 miles per hour and a "Tornado South on Ground Moving NE!" The tornado caused approximately $10 million in damages.

March 25, 1948: First Official Tornado Forecast

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

1948: Pioneering Tornado Forecasting by the USAF

In 1948, The USAF had pioneered tornado forecasting and tornado warnings. Before this time the US Weather Bureau feared that tornado forecasts were insufficiently reliable and that such warnings would incite panic among the public.

March 25, 1949: Successful Tornado Forecast in Southeastern Oklahoma

On March 25, 1949, Miller and Fawbush successfully predicted tornadic activity would occur in southeastern Oklahoma.

July 12, 1950: Tornado Warning Ban Lifted

On July 12, 1950, Chief of the Weather Bureau, Francis W. Reichelderfer, officially revoked the ban on issuing tornado warnings to the general public through a Circular Letter. The letter encouraged Weather Bureau employees to be willing to make tornado forecasts when a "good probability of verification" exists.

1951: Formation of the Severe Weather Warning Center

In 1951, the Air Force established the Severe Weather Warning Center (SWWC) to relay severe weather forecasts to Weather Bureau offices and emergency personnel in tornado-prone areas.

March 1952: Weather Bureau Issues First Experimental Public Tornado Forecast

In March 1952, the Weather Bureau issued its first experimental public tornado forecast, which proved inaccurate and was released too late to be widely available. However, a forecast issued the following evening successfully predicted an outbreak of tornadoes across a seven-state area.

1954: First Televised Tornado Warning Broadcast

In 1954, meteorologist Harry Volkman broadcast the first televised tornado warning over WKY-TV in Oklahoma City, defying the Federal Communications Commission's ban. His actions were motivated by the belief that the ban on tornado warnings over broadcast media cost lives.

1974: Discussion of the Last Tornado Alert

Following the 1974 Super Outbreak, the last tornado alert to be officially issued was discussed, leading to its eventual elimination due to the advent of Doppler weather radar.

1974: Decline of Tornado Alerts

In 1974, the National Weather Service began to decrease its use of tornado alerts, an intermediate advisory indicating imminent tornado formation.

1974: Average Tornado Warning Times

In 1974, the average tornado warning times were approximately -10 to -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 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 due to improvements in the tornado warning system.

September 20, 2002: Tornado Emergency 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: Change in Warning Issuance

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

2008: Implementation of Emergency Management Ontario

In 2008, Emergency Management Ontario implemented a system to issue red alerts for sections of the province under an Environment Canada-issued tornado warning.

March 2012: Implementation of Impact Based Warning System

In March 2012, the NWS Weather Forecast Offices in Wichita and Topeka, Kansas, and Springfield, St. Louis and Kansas City/Pleasant Hill, Missouri, 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

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

2013: Improved Tornado Warning Times

As of 2013, average tornado warning times have increased to about 15 minutes, with some lead times extending to over an hour.

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 Impact Based Warning (IBW) indicators.

2016: Agency-Wide IBW Implementation

In 2016, the entire National Weather Service agency began using the Impact Based Warning (IBW) format.

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 for Warning Bulletins

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

April 2023: Introduction of TORNADO Act

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