The Widespread Tornado Outbreak of April 3-4, 1974


Description of the Outbreak

In terms of total number, path length, and total damage, the massive tornado
occurrence of April 3-4, 1974, was more extensive than all previously known
outbreaks. Of the 127 tornadoes so far documented (148 tornadoes according
to revised statistics by T. Theodore Fujita, The University of Chicago), 118
had paths over a mile long. The total paths amounted to 2,014 miles (2,500
miles according to revised statistics by Mr. Fujita), resulting in 335
deaths (330 deaths according to revised statistics by Mr. Fujita). By
comparison, during the tri-State out-break of March 18, 1925, seven
tornadoes traveled 437 miles and caused 746 deaths. The Palm Sunday outbreak
of April 11, 1965, spawned 31 tornadoes, which had paths totaling 853 miles,
and killed 256.

The year 1973 went down in history as the year of the tornado. More than
1,100 tornadoes were reported--an all-time high. The first quarter of 1974
was just as busy, but severe weather forecasts generally were confined to a
few watch areas on each storm day. This pattern was broken on Monday, April
1, when 11 severe weather watch areas were issued and more than 20 tornadoes
developed from Alabama and Mississippi through the central States into
Indiana and Ohio. Three deaths and much property damage were attributed to
tornadoes. The storms of April 1 served to alert the forecasters to the
potential for widespread outbreaks, and the impact of these storms was fresh
in the minds of many people when they heard the watches and warnings of
April 3. In Alabama and Tennessee, where severe damage occurred on both
days, many lives were saved during the April 3-4 disaster because the public
took protective actions that might not otherwise have been taken had it not
been for the April I storms.

On Tuesday morning, April 2, the forecasters at the NSSFC determined that
the developing storm system had the potential to produce severe
thunderstorms the following day, although the precise location and timing Of
Such activity was not yet evident. At that time, it appeared that the severe
activity would occur somewhere in the middle or lower Mississippi Valley.
Consequently, the Kansas City RWCC suggested in a teletypewriter message to
10 Central Region network radar stations that any needed maintenance be done
by April 2. (Stations alerted were Garden City and Wichita, Kans.; Grand
Island, Neb.; St. Louis and Monett, Mo.; Detroit, Mich.; Des Moines, Iowa;
Minneapolis, Minn.; Marseilles, Ill.; and Evansville, Ind.) Meanwhile, the
Fort Worth RWCC was phoning to advise several Southern Region WSFOs of the
coming severe weather potential and the need for radar maintenance. (Offices
contacted were WSFOs in Oklahoma City, Little Rock, Memphis, Birmingham, and
Jackson.)

While this preliminary alert did not extend far enough east to include all
the tornadoes that occurred, and did include a large area in the central and
southern plains in which severe thunderstorms did not occur, it gave many
NOAA offices over 24 hours in which to prepare for the outbreak.

Through the night on Tuesday, indications of the storms to come were
accumulating but the tremendous magnitude and intensity of what was actually
to occur, as well as the precise timing and location of the storms, were
still not evident. Two severe weather watches were issued during the predawn
hours on Wednesday, April 3, for portions of the lower Mississippi Valley,
but little activity was noted in these areas. The pace increased in the
NSSFC and field offices during the forenoon, as thunderstorms began to
build. Severe Thunderstorm Watch No. 92 covering portions of the Ohio Valley
was issued at 8:27 a.m. CDT. From that time until 3:00 a.m. CDT the next
morning, NSSFC issued 28 Severe Weather Watches covering almost the entire
area from the Gulf of Mexico to the Canadian border and from the,
Mississippi River to the East Coast. During this period, National Weather
Service Offices issued about 150 tornado warnings. The major activity
occurred between 2:00 p.m. and 10:00 p.m. on April 3. In all, 13 States had
tornadoes.

The rapid development and widespread extent of the tornado outbreak are
evident in the reported times of the first tornado in the seven States
struck during the afternoon hours of April 3. Around 2:00 p.m. CDT,
tornadoes touched down in Bradley County, Tenn., and Gilmer County, Ga.
Within 10 minutes, tornadoes were reported in McLean and Logan Counties,
Ill. At 2:20 p.m. CDT, separate killer storms set down in the Indiana
counties of Perry and Lawrence. In Ohio the first tornado was reported about
3:30 p.m. CDT, and the Brandenburg, Ky., storm touched down at 3:40 p.m.
Alabama's first tornado followed by less than an hour, striking 8 miles west
of Birmingham at 4:30 p.m. CDT.

For comparative purposes, for all the tornadoes reported during this
outbreak, the mean path length was on the order of 18.7 miles whereas the
mean path length for all tornadoes in 1973 was 4.7 miles. For all tornadoes
in 1972 it was 3.3 miles. In a rating of intensity of tornadoes on a scale
from F0 to F5, six tornadoes in this outbreak had an intensity of F5. In
1973, only one tornado had an intensity of F5. In 1972, no tornadoes reached
this intensity. In 1971, two tornadoes had an intensity of F5.

Of the casualties and losses suffered in the 13 States surveyed by the
American Red Cross, some were caused by straight-line winds rather than
tornadic-storms, particularly those involving mobile homes. Some of the
deaths reported by the Red Cross were caused by heart attacks and not by
direct storm injury. Large hail during the severe thunderstorms and
tornadoes contributed to the total damage. The States of Alabama, Georgia,
Tennessee, Kentucky, Indiana, and Ohio were the region of greatest storm
activity and damage. Detailed descriptions of tornado activity in each State
are provided in the sections that follow. The extremely large number of
storms that occurred, and their rapid movement, magnified the problems
involved in determining the number and sequence of events. Detailed studies
of individual storms and further analyses may modify the descriptions given
in this report.


Super Outbreak Statistical Data - Complied by T Fujita

The Fujita -Pearson Scale

F Intensity P - Path Length P - Mean Width
F0 Light Damage P0 Less than 1 mile P0 less than .01 mile
F1 Moderate Damage P1 1.0 to 3.1 P1 0.01 to 0.03
F2 Considerable Damage P2 3.2 to 9.9 P2 0.04 0.09
F3 Severe Damage P3 10 to 31 P3 0.1 to 0.31
F4 Devastating Damage P4 32 to 99 P4 0.32 to 0.99
F5 Incredible Damage P5 100 or longer P5 1.0 or wider


Source: Tornado Superoutbreak site.


My Comment:

6 Tornadoes were of the F5 level out of the 148 recorded. Many were of
level 2, 3 and 4.

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Gavin Staples.

Cambridge, UK.
website updated regularly
www.gavinstaples.com



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