History of Tornado warning in Timeline

A tornado warning is issued when a tornado has been sighted or indicated by radar, posing an imminent threat to an area. These warnings prompt people to seek immediate shelter. Modern Doppler radar can detect rotation within thunderstorms, enabling early warnings even before a tornado forms. Visual confirmation from weather spotters or the public, including sightings of a funnel cloud, wall cloud, or the tornado itself, also triggers warnings. Such ground truth observations are especially important in areas with limited radar coverage, where tornadoes may develop undetected.

April 1908: U.S. Weather Bureau published replies on tornado protection

In April 1908, the U.S. Weather Bureau published several replies regarding a question posed to the Weather Bureau on how to protect against tornadoes.

March 1925: Tri-State Tornado

In March 1925, the Tri-State Tornado occurred, which is the deadliest tornado in U.S. history.

1925: Tornado death rate

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

1938: Weather Bureau rescinded ban on the word tornado

In 1938, the Weather Bureau rescinded its ban on the usage of the word "tornado" in weather products disseminated to emergency management personnel.

April 1947: Glazier–Higgins–Woodward tornadoes

In April 1947, the Glazier–Higgins–Woodward tornadoes happened.

March 20, 1948: Tornado hit Tinker Air Force Base

On March 20, 1948, a tornado struck Tinker Air Force Base, damaging several military aircraft, with total damage estimated at $10 million.

March 25, 1948: First official tornado forecast made

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

1948: Lack of warning resulted in increase in tornado-related fatalities

Before 1948, the lack of warning resulted in a steady increase in the number of tornado-related fatalities.

March 25, 1949: Miller and Fawbush successfully predicted tornadic activity

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

July 12, 1950: Ban on tornado warnings lifted

On July 12, 1950, Chief of the Weather Bureau Francis W. Reichelderfer officially lifted the ban on issuing tornado warnings to the general public.

1951: Formation of the Severe Weather Warning Center

In 1951, the Air Force began issuing severe weather forecasts relayed to Weather Bureau offices and emergency personnel in tornado-prone regions through the formation of the Severe Weather Warning Center.

March 1952: First experimental public tornado forecast

In March 1952, the Weather Bureau issued its first experimental public tornado forecast, which proved inaccurate.

1954: First televised tornado warning

In 1954, meteorologist Harry Volkman broadcast the first televised tornado warning over WKY-TV in Oklahoma City.

1974: Super Outbreak Impacts Tornado Alert Discussions

Following the 1974 Super Outbreak, discussions ensued regarding the last official tornado alert. The advent of Doppler weather radar made tornado alerts obsolete by detecting rotational funnel cloud formations earlier than trained spotters and members of the public. Radar also helped reduce public confusion over storm types, strengths and precise locations.

1974: Average tornado warning times

In 1974, the average tornado warning times was -10 to -15 minutes.

1974: Tornado Alert System in Use

Until the early 1980s, an intermediate type of tornado advisory known as a tornado alert was defined by the National Weather Service. In 1974, these alerts indicated imminent tornado formation based on visible rotation in clouds and other phenomena. The National Weather Service began to reduce its use of this advisory 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. This caused major damage exceeding $1 billion. A tornado emergency is a severe weather statement with enhanced wording that is disseminated when reliable sources confirm a violent tornado that poses a catastrophic risk for damage and threat to human life.

2000: Tornado death rate declined

In 2000, the tornado death rate declined to only 0.11 per million people.

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. This illustrates that a tornado emergency can be declared even at the start of a warning if the situation warrants it due to significant threat to life and property.

October 2007: Warnings were issued by the National Weather Service on a per-county basis

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

2008: Emergency Management Ontario Implements Red Alerts

In 2008, Emergency Management Ontario implemented a system to issue red alerts for sections of the province under an Environment Canada-issued tornado warning. This system can sometimes override the tornado warning if local government or media outlets participate in the program. The alerts are also disseminated through various channels, including broadcast media, online outlets, and cellular phones.

March 2012: Implementation of Impact Based Warning system

In March 2012, the NWS Weather Forecast Offices began incorporating categorical tornado and damage threat indicators for visually confirmed and radar-indicated tornadoes.

March 2013: Expanded threat and damage indicators

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

2013: Average tornado warning times increased

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

March 2014: Additional offices began using the IBW indicators

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

2016: The entire agency began using the format

In 2016, the entire agency began using the format of categorical tornado and damage threat indicators.

August 15, 2020: Tornado warning for pyrocumulonimbus

On August 15, 2020, the National Weather Service issued a tornado warning for pyrocumulonimbus capable of producing a tornado in southeastern Lassen County, California.

July 2021: IBW formatting was fully implemented

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.