George H. Taylor, Holly Bohman, and Luke Foster
Oregon Climate Service, Oregon State University
August, 1996
Introduction
Tornadoes are the most concentrated and violent storm produced by the earth's
atmosphere. A tornado, whose name comes from the Latin word toronae ("to
turn"), is a vortex of rotating winds and strong vertical motion which
possesses remarkable strength and can cause almost unbelievable damage.
Wind speeds in excess of 300 mph have been observed within tornadoes, and
it is suspected that some tornado winds exceed 400 mph. In addition, the
low pressure at the center of a tornado can literally explode buildings
and other structures that it passes over.
Tornadoes have been observed throughout the United States, but are especially
common in the Midwest; in fact, the midwestern U.S. has more tornadoes than
any other place on earth. The largest numbers of observed tornadoes in the
U.S. in the first half of the 20th century occurred in Kansas, Iowa, Texas,
and Oklahoma. West of the Rockies, however, tornadoes are infrequent and
generally small compared with their midwestern counterparts. Nonetheless,
Oregon and other western states have experienced tornadoes on occasion,
many of them producing significant damage, and occasionally causing injury
or death.
While tornadoes are sometimes formed in association with large Pacific storms
arriving from the west, most of them are caused by intense local thunderstorms.
These storms, which usually also produce thunder, lightning, hail, and heavy
rain, are more common during the warm season (April to October).
Oregon Tornadoes
Because of Oregon's relatively low population, many tornadoes probably go
unreported. Not surprisingly, most of the tornadoes identified in this report
occurred near populated areas. In a few cases, tornadoes were identified
from the damage they caused rather than by eyewitness.
Table 1 lists significant tornadoes reported
in Oregon between 1887 and 1996; Figure 1 is
a map showing each location listed in the table. The generally minimal damages
which have accompanied most of the tornadoes prove that such storms are
not significant threats to people or property. In fact, even the strongest
Oregon tornadoes would be considered relatively insignificant in the midwestern
U.S. where the truly devastating storms are observed.
Below are descriptions of some of the stronger, more damaging, or more unusual
tornadoes which have been reported.
* June 1887 -- Long Creek. The earliest documented tornado reports occurred
on June 14, 1887. On that day a strong thunderstorm produced tornadoes which
struck Lexington in Morrow County and Long Creek in Grant County. These
tornadoes caused considerable damage to farmland and timber. In addition,
the Lexington tornado produced one death, the only one which has ever resulted
from a tornado in Oregon.
* June 1937--Baker County. A severe thunderstorm which included hail and
at least one tornado struck the Baker City vicinity at about 9:30 a.m. A
barn was wrecked and a brick church was moved about 15 inches off its foundation.
A cow was carried 60 feet through the air and deposited upside down, with
neither hair nor skin remaining. Five large pine trees surrounding a house
were blown down, but the house escaped damage. Only one injury occurred:
a woman walking down Main Street became entangled in a barbed-wire fence
blown through the air; she remained there, unable to move, until the storm
was over. There was extensive damage to farm products, including alfalfa,
grain, and livestock.
* January 1953--Corvallis. A combination of hail, heavy rain, and a tornado
caused significant damage in Corvallis on January 19, 1953. Abundant rains
earlier that month had caused localized flooding, with the Willamette River
more than four feet above flood stage. A powerful thunderstorm formed west
of Corvallis and moved through the city. A number of roofs were ripped from
houses and other buildings, and many of these were later damaged by heavy
rainfall. Power lines were torn out, trees were uprooted, and windows were
smashed. A small black dog was picked up and carried about a block; when
he landed again he started running and was running when last seen. As the
tornado moved through Corvallis, its path seemed to "bounce,"
striking about every other block. A downtown roof was carried across the
street, striking a huge transformer and cutting off electricity for the
entire downtown section. The tornado, the first to ever hit Corvallis, blew
itself out as it crossed the Willamette River.
* April 1957 -- Portland area. One of the most memorable days in Oregon's
tornado history occurred on April 12, 1957. A very strong storm system brought
heavy rains and high winds to the area from the 12th through the 14th, with
wind gusts reaching 70 mph on the 14th. At about noon on the 12th, a very
dark storm cloud appeared near the city of Sandy, about 25 miles SE of Portland.
Heavy rain began to fall, and then small hail. The hail stones grew larger,
reaching diameters of one quarter to one half inch. As the storm moved east
from Sandy, a funnel cloud emerged and reached downward, eventually touching
the ground and becoming a 50 yard wide tornado. The tornado churned through
the farmland of Sandy heading toward the Cascades. Large fir trees, 18 to
36 inches in diameter were twisted off or snapped 30 to 40 feet above the
ground. A large barn under construction was lifted off its foundation, carried
several hundred feet in the air, and then dropped back to the ground, shattering
it to pieces. Roofs of houses and barns were torn off and some farm outbuildings
were carried a considerable distance before being destroyed.
Shortly thereafter, west of the small farm town of Ione in Gilliam County,
a long thin funnel cloud was observed descending from a similar dark storm
cloud. This tornado was much larger than the Sandy tornado (it was 100-400
yards wide) and had a much longer path (15-20 miles). Fortunately, this
area is largely range land and large wheat farms, and no buildings were
in the path of the tornado. Several telephone poles were pulled out of the
ground and some damage was done to fields, but this was generally minor.
In fact, much of the damage may have been caused by the large amounts of
hail that accompanied the tornado. In the Heppner area, a few hail stones
exceeding one inch in diameter were found.
* June 1968--Northeastern Oregon. The most damaging (and probably the most
mysterious) tornado in Oregon occurred during the late afternoon on June
11, 1968. A very strong thunderstorm formed over Wallowa County in extreme
northeastern Oregon. The tornado spawned by this storm touched down in mountainous,
forested areas which were mostly uninhabited. For that reason, there were
virtually no eyewitnesses to this tornado, but its status as a tornado seems
certain because of the sheer size of its path and the degree of destruction.
A swath of destruction one half to two miles wide and 8 to 10 miles long
was created by this storm, and destruction along the path was very significant.
About 1800 acres of prime timber was destroyed and another 1200 acres were
badly damaged. It was estimated that over 40 million board feet of lumber
were blown down by the tornado. Hail stones that accompanied the tornado
were reportedly of golf ball size in some cases.
* January 1996--Lincoln City. Oregon tornadoes are reported chiefly in the
Willamette Valley and in flatlands of eastern Oregon; only rarely do they
affect the Oregon coast. In 1996, an apparent tornado struck the coasts
near Lincoln City. There were no eyewitnesses, since this occurred at night,
but the damage which resulted makes it evident that a tornado did occur.
An intense electrical storm, one of the strongest in recent years, occurred
late one January night. Thunder, lightning, and high winds lasted for several
hours. The next day, several damage reports were received by the Lincoln
City police. In the parking lot of a manufactured home facility, a trailer
was lifted completely off the ground and dropped on the trailer adjacent
to it. Several windows were shattered, the glass exploding outward as if
the result of extremely low outside pressure. Near the ocean, a number of
fish were apparently pulled from the ocean and dropped onto a parking lot.
Based on the nature of the reports, it appears that a tornado passed through
Lincoln City that night.
