fire burns in the Tower Plaza Addition in Moore, Okla.,
following a tornado Monday, May 20, 2013. A tornado as much
as half a mile wide with winds up to 200 mph roared through
the Oklahoma City suburbs Monday, flattening entire
neighborhoods, setting buildings on fire and landing a
direct blow on an elementary school.
TULSA, Okla. —
Deadly tornadoes that have raked communities in Middle America
over the past week, including Monday's massive twister that carved
a path of destruction through the Oklahoma City suburb of Moore,
belie what had been a relatively quiet start of the 2013 tornado
In fact, this is
the longest the U.S. has gone into May without registering an EF1
or stronger tornado, which are the types that can cause damage.
That's according to Harold Brooks, a research meteorologist at the
National Severe Storms Laboratory.
An unusually cool
spring kept the funnel clouds at bay until mid-May, or about a
month after they'd typically begin their deadly dance in this part
of the country. But that calm melted away with the recent rise in
temperatures and humidity in the Plains and Midwest that produced
ideal temperatures for the tornadoes that have killed people in
Oklahoma and Texas since last Wednesday.
happened over the last week, and for quite a while there, was a
ridge in the atmosphere that stayed over the western United
States, and that is a pretty unfavorable pattern for
tornadoes," said Brooks. "But, over the last few days,
the ridge has moved east and the trough flow came over central
United States. On Saturday, we got a lot of moisture that returned
from Gulf of Mexico, and when you bring those ingredients
together, something's going to happen."
have fallen markedly in the U.S. since the 2011 season, when the
country was hit over and over by killer twisters. April 2011 had
497 EF1 or stronger tornadoes, which are the types that can cause
damage. That's not only a record, but it's more than the next two
highest months combined, Brooks said.
From June 2010
through May 2011, there were 1,050 EF1 or stronger tornadoes,
which was a record high for a 12-month period. Then just a year
later, a record tornado drought began. From May 2011 through April
2013, there were only 217 tornadoes, 30 fewer than the old record.
look for victims under debris from a tornado that passed
across south Oklahoma City, Monday, May 20, 2013. A
monstrous tornado roared through the Oklahoma City suburbs,
flattening entire neighborhoods with winds up to 200 mph,
setting buildings on fire and landing a direct blow on an
unusually late start to the season was caused by unseasonably cool
weather marked by unusual upper air patterns that suppressed storm
development for much of the early tornado season, Brooks said.
devastating touch down in Moore shows, a slow start of the season
says nothing about how it how it could eventually shape up.
quiet in February through April; that doesn't tell us anything
that will happen in May," Brooks said.
aerial photo shows the remains of homes hit by a massive
tornado in Moore, Okla., Monday May 20, 2013. A tornado
roared through the Oklahoma City suburbs Monday, flattening
entire neighborhoods, setting buildings on fire and landing
a direct blow on an elementary school.
residents frantically searched the wreckage of schools and homes
destroyed by Monday's strike, communities elsewhere in Oklahoma
and the region were bracing for the possibility of new funnel
clouds or huge hail stones.
Hours before the
Moore strike, National Weather Service meteorologist Peter Snyder
predicted that twisters could touch down in the region and other
areas to the east.
good environment for super cell development and it could develop a
squall line that produces 70 mph wind and clusters of
thunderstorms," Snyder said. "It's a similar situation
(as Sunday) but it will affect points east today."
tornado strikes began Wednesday, when a twister outbreak in North
Texas killed six people and injured dozens of others, many in the
community of Granbury. A massive storm system that moved through
the Plains and Midwest on Sunday produced tornadoes in Kansas and
Iowa, but it was Oklahoma that bore the brunt of the destruction,
with at least 39 injured throughout the state and two deaths from
a tornado strike near Shawnee, 30 miles east of Moore.