April 3–4, 1974 Super Outbreak

NOAA’s data tells the story of one of the worst tornado outbreaks in U.S. history 50 years later

Black and white image of storms on WSR-57 radar scope on April 3, 1974. A “hook echo” or hook-shaped storm cell indicating a severe and potentially tornadic storm can be seen in the upper left corner of the image.

Image courtesy of NOAA Natural Disaster Survey Report: The Widespread Tornado Outbreak of April 3–4, 1974.

Map of U.S. states impacted by tornadoes in the tornado Super Outbreak of 1974 with 148 tornado tracks plotted as lines from April 3–4, 1974. — *Map of U.S. impacted by tornadoes in the tornado Super Outbreak of 1974 with 148 tornado tracks plotted from April 3–4, 1974. Image courtesy of NOAA Natural Disaster Survey Report.* *The Widespread Tornado Outbreak of April 3–4, 1974, reproduced from Fujita (1975).*

The “Super Outbreak” that struck much of the central and eastern U.S. and parts of Canada on April 3-4, 1974 holds numerous tornado-related records to this day, including the largest number of F5* tornadoes in a single outbreak (Corfidi et al., 2004) and the second-highest number of tornadoes in a single day, behind only the Super Outbreak of 2011.

Many of the tornadoes that occurred as part of the outbreak are known for their significance on their own. Examples include deadly, long-track F5 tornadoes that devastated Xenia, Ohio, Brandenburg, Kentucky, and Guin, Alabama, among many others.

Aerial black and white photos of the large Xenia High School in Xenia, Ohio and nearby residences before (top) and after (bottom) a direct hit from an F5 tornado on April 3, 1974. The bottom photo after the tornado shows total destruction of almost all structures and scattered debris. — Aerial photos of Xenia High School in Xenia, Ohio and nearby residences before (top) and after (bottom) a direct hit from an F5 tornado on April 3, 1974. Image courtesy of NOAA Natural Disaster Survey Report *The Widespread Tornado Outbreak of April 3–4, 1974*.

The human toll of the outbreak can never be fully accounted for, but some statistics related to the outbreak help present an idea of its significance:

148 confirmed tornadoes in the U.S. and Canada
30 F4 and F5 tornadoes
The total path length of all tornadoes in the outbreak: 2,598 miles
335 direct fatalities
Over 6,000 injured
13 states (plus an F3 in Ontario)
2024 CPI-adjusted losses of approximately $5.3 billion**

*The currently used Enhanced Fujita Scale (EF-scale) for rating tornadoes was not implemented until 2007, with all tornadoes rated before that using the Fujita (F) scale retaining their rating.

**NCEI Billion-Dollar Disasters product accounts only for disasters from 1980 and after, so the 1974 Super Outbreak does not appear.

Meteorology

On April 2, 1974, a circulation that would eventually become a strong low pressure system began to develop on the lee side of the Rocky Mountains in Colorado.

Black and white map of the continental U.S. 850mb analysis from 1200 GMT April 3, 1974 with contours showing height and temperature and hatching showing areas with wind speeds greater than 50kt (~58mph). An “L” marks the center of a strong low pressure system centered over northern Kansas. — Map of the U.S. 850mb analysis from 1200 GMT April 3, 1974 with contours showing height and temperature and hatching showing areas with wind speeds greater than 50kt (~58mph). An “L” marks the center of a strong low pressure system centered over northern Kansas.

By the morning of April 3, strong winds at both the upper and lower levels of the atmosphere and a stark contrast between the dry air to its northwest and warm, moist Gulf air to its southeast helped the system to develop explosively. Those same atmospheric conditions set the stage for plentiful wind shear (winds changing speed and direction at different levels of the atmosphere) and instability (available energy in the atmosphere) ahead of the system as it raced across the U.S., combining all ingredients needed for a major outbreak of severe storms, especially strong tornadoes.

Observing the Outbreak

During the outbreak, National Weather Service (NWS) meteorologists used the Weather Surveillance Radar-1957 (WSR-57) to detect and warn of severe and tornadic thunderstorms. It may not look comparable to radar imagery we see today (most of which is from the newer WSR-88D, or Weather Surveillance Radar-1988 Doppler radars in the U.S.), but this imagery proved critical in saving many lives.

A NASA satellite with early environmental surveillance capabilities, the Applications Technology Satellite 3 (ATS-3), gave a much wider view of the intense low pressure system and associated frontal boundaries that brought devastating severe weather to much of the eastern half of the country during the Super Outbreak.

ATS-3 visible satellite images showing the typical “comma shape” cloud structure of the strong low pressure system over the central and eastern U.S. that generated the 1974 Super Outbreak from 2100 GMT (top) and 2114 GMT (bottom) on April 3, 1974. — *ATS-3 visible satellite images of the strong low pressure system that generated the 1974 Super Outbreak from 2100 GMT (top) and 2114 GMT (bottom) on April 3, 1974. Images Courtesy of* *University of Wisconsin CIMSS* *and NASA.*

Storm Data Provides Insight

NCEI maintains and stewards the Storm Events Database, which was used to create the NOAA Storm Data Publication. It documented “the occurrence of storms and other significant weather phenomena having sufficient intensity to cause loss of life, injuries, significant property damage, and/or disruption to commerce.” It also cataloged rare or unusual weather phenomena that generated media attention, such as snow in South Florida, or other significant meteorological events like record minimum/maximum temperatures or precipitation.

The Storm Data Publication for April 1974 details the numerous tornadoes, extensive damage, and deaths/injuries that occurred across 13 states in the U.S. during the Super Outbreak. While tornadoes are usually highlighted as the most dangerous and deadly phenomena of the outbreak, numerous severe storms that did not produce tornadoes still resulted in significant damage due to strong straight-line winds and large hail.

Warnings, Communications, and a Path Forward

A NOAA Disaster Assessment Report about the outbreak found that though the performance of the NWS was admirable under the extreme conditions presented by the outbreak, gaps in storm detection, warnings, and communication existed. These findings were used to inform warning and communication strategies that helped modernize the NWS and its warning capabilities.

Black and white map of much of the eastern U.S. with counties for which tornado warnings were issued during the Super Outbreak of 1974 highlighted in gray (counties cover 13 U.S. states). — *Grey highlights indicate counties for which tornado warnings were issued from April 3–4, 1974 during the Super Outbreak. Image courtesy of NOAA Natural Disaster Survey Report* *The Widespread Tornado Outbreak of April 3–4, 1974*.

It was noted that though there was a significant loss of life during the outbreak and that NWS warnings did help to prevent many deaths, many lives were spared due to good fortune with the timing and tracks of tornadoes (i.e., the Xenia, Ohio F5 struck the town just hours after school dismissal, likely preventing catastrophic losses). Better communication with all sectors involved in hazardous weather preparation and emergency response, notably mass media and emergency management, was borne of the outbreak, helping to preserve life and property up to the present and beyond.

The outbreak also highlighted the need for enhanced weather and storm observing capabilities across the U.S. and beyond, spurring the funding and development of new technologies in radar and satellite meteorology, many of which are still in use in the NWS to this day. For local weather forecasts, see the NWS and for severe weather forecasting and outlooks up to eight days in advance, see the Storm Prediction Center.

Published

April 3, 2024