Geoscience Reference
In-Depth Information
storm killed 16 people, caused $100 million in damage (1966
dollars), and led to my lifelong interest in geography. Some-
times atmospheric conditions are so ripe that a
tornado out-
break
occurs, with numerous funnels over several hours or a
couple of days. Such an outbreak occurred in early May 2007
when over 100 tornadoes were reported in the central Great
Plains. The most severe of these storms hit Greensburg, Kan-
sas, and caused damage of over $153 million. This storm was
the first EF5 tornado ever reported, with estimated winds of
330 km/h (205 mph) in the core of the system. Approximately
95% of the town was destroyed in this storm (Figure 8.19).
Since the Greensburg tornado, catastrophic EF5 tornadoes
also struck Joplin, Missouri, and Moore, Oklahoma, in 2011
and 2013, respectively.
Although the central part of the country is most known
for tornadoes, large and dangerous twisters are also common
in the southeastern United States in states such as Arkansas,
Alabama, Mississippi, and Georgia. Tornadic storms usually
occur in this part of the country during the early spring because
the jet stream is still flowing over the southern states. Some
of the strongest storms in the country have occurred in this
region, with the most recent intensive tornado outbreak occur-
ring from April 25 to 28, 2011. This outbreak produced over
350 confirmed tornadoes, with four EF5s. Perhaps the most
widely reported tornado was a storm that struck Tuscaloosa,
Alabama, which is home to the University of Alabama. This
tornado was on the ground for 130 km (81 mi) and killed 43
people. Overall, more than 325 people died within the region
due to the outbreak.
Human Interactions: Tornado Monitoring
Although
studying tornadoes is interesting purely from a meteorologic
perspective, the primary goal of tornado research is to im-
prove public safety. In this context, the National Weather Ser-
vice constantly monitors atmospheric conditions and makes
public announcements as weather events unfold on any given
day. A
tornado watch
is issued for an area, such as the eastern
part of Oklahoma or central Texas, when atmospheric condi-
tions are favorable for the development of tornadoes. When
an actual funnel or tornado has been identified, a
tornado
warning
is issued for a specific place or, perhaps, county.
At this time sirens are sounded, and people are advised to
seek shelter, either in a low-lying ditch or, preferably, in a
basement.
With respect to tornado monitoring, the most significant
technological development in the past few decades has been
Doppler radar, such as the Next Generation Weather Radar
(NEXRAD) used by the National Weather Service (Figure 8.20).
Prior to this development, tornado warnings were based largely
on direct observations, which were often too late to save lives.
(a)
(b)
Figure 8.19 The Greensburg Tornado.
(a) In May 2007, an
EF5 tornado struck Greensburg, Kansas, killing 11 people and
destroying 95% of the town. (b) Air photo of Greensburg before
the tornado. (c) Air photo of Greensburg after the tornado. Note
that most of the town was essentially destroyed.
(c)
