Violent weather like tornadoes and severe thunderstorms can be deadly, causing around 60 deaths, 1,500 injuries, and $400 million in damage annually in the US. A single historic tornado in 1925 killed nearly 700 people across several towns in Illinois. To increase chances of survival, these severe storms must be taken seriously. The document provides information on tornado watches versus warnings and safety measures to take before, during, and after severe weather strikes.

1. Signals that severe weather is about to strike can be foreboding, and it’s further unnerving to know if a tornado
is forming, its path will be unpredictable, and it will show no mercy.
Mysterious and menacing, tornadoes and severe thunderstorms also are destructive and deadly. On average,
more than 1,200 tornadoes per year strike in the United States, killing about 60 people, injuring 1,500 and
causing about $400 million in damage. A single tornado killed an estimated 695 people over a 219-mile stretch
in 1925, including at least 234 in one town (Murphysboro, Illinois).
Violent weather must be taken seriously if those in its path are to increase their chances of survival. This severe
storm information guide explains severe thunderstorms and tornadoes in more detail, including the importance
of being aware of the warning signs.
WHERE AND WHEN THUNDERSTORMS AND TORNADOES OCCUR
While tornadoes can occur at any time and have been reported in all 50 states, the peak season is April through
July, and they are most common in the central and southeastern states. Data collected by USTornadoes.com
from the National Weather Service’s Storm Prediction Center shows that over a 25-year period, an average of
269 tornadoes occurred in the contiguous U.S. states in May, followed by 229 in June. April (178) and July (123)
were next, with the other eight months all averaging 75 or fewer. A vast majority — 78 percent — took place in
spring or summer. Texas (146.7) is the only state that averaged more than 100 tornadoes per year, but 10 other
states averaged 45 or more: Kansas, Oklahoma, Florida, Nebraska, Illinois, Colorado, Iowa, Alabama, Missouri and
Mississippi. Tornado “season” varies geographically, moving northward between May and midsummer.
Source: http://www.ustornadoes.com/2016/04/06/annual-and-monthly-tornado-averages-across-the-united-states/
HOW A TORNADO WATCH DIFFERS FROM A TORNADO WARNING
A tornado watch is issued when conditions are favorable for a tornado to form within the next several hours.
People should stay alert, spread awareness to family and friends, and have a plan to move to a safe place as it
becomes necessary. Tornado watches are issued by the Storm Prediction Center.
A tornado warning is issued when a tornado has been spotted or a Doppler radar shows a thunderstorm
circulation pattern very favorable for spawning a tornado. Danger is imminent, and safety measures should be
taken immediately. The National Weather Service issues tornado warnings through its local offices.
Severe Storm Guide
What you need to know about
tornadoes and severe thunderstorms
The skies blacken.
Clouds swell and roll with an unnatural fury.
The wind roars, and thunder crackles.
Before
Watch for storm signs (blackening skies, rotation in
cloud base, lightning, wind shift, loud roar or rumble
that isn’t thunder).
Go indoors if you hear thunder.
Listen for community-issued alerts/sirens and severe
weather information.
Check on elderly/disabled.
Evacuate a mobile home for a safer site.
Gather pre-made emergency supply kits (first aid,
food, water, flashlight, can opener, cash, family and
emergency services contact info, etc.).
Secure outdoor loose items that could become
projectiles.
Heed warnings; conditions can deteriorate quickly.
During
Move to a safe room, or inner room on the lowest
floor of a sturdy building.
Include pets if time allows.
Do not station yourself in places where a heavy object
(refrigerator, piano, etc.) rests on the floor above.
Stay away from windows.
Wear head protection if available.
Use blankets/mattresses, etc., to protect yourself
from potential flying debris.
Don’t shower, bathe or use other indoor plumbing.
Stay informed, via NOAA Weather Radio, TV or online
news, or cellphone alerts.
Avoid electrical equipment and corded phones
(cordless devices are OK).
If outside with no shelter available, avoid high ground,
water, tall trees, utility poles, and metal objects that
attract lightning and conduct electricity (i.e., metal
fences).
If in a vehicle, park and move to a ditch well below
roadway level; if there is no such spot, then make sure
seat belt is on and duck below window level and cover
head with a blanket or arms.
After
Provide first aid to the injured until first responders
arrive.
Wear protective clothing when walking through a
tornado site.
Avoid and report fallen power lines.
Be alert for and report broken gas lines.
Open a window and evacuate building quickly if you
smell gas.
Avoid damaged buildings.
Do not use matches, candles or lighters; a gas line
could have broken.
Do not use a portable generator indoors (including
garage) even if there’s a power outage (risk of carbon
monoxide poisoning).
If out of town, don’t return home until authorities
give clearance.
12 FAQS ABOUT TORNADOES
AND THUNDERSTORMS
What is a tornado?
A tornado is a column of air that rotates violently, and
it must extend from the base of a thunderstorm to the
ground — otherwise it is classified only as a funnel cloud.
The most violent of atmospheric storms, a tornado can
be difficult to see unless it forms a funnel consisting
of condensation, dust and debris. Most tornadoes last
about 10 minutes and travel 3½ miles on average.
When are thunderstorms classified as “severe”?
When a thunderstorm includes wind gusts of at least
58 mph or produces hail at least an inch in diameter.
A severe thunderstorm warning should be treated with
the same seriousness as a tornado warning.
A thunderstorm seems to be quite a distance
away. Am I safe?
No. Lightning can strike 10 miles away from rainfall,
especially in the western U.S. Also, local conditions can
deteriorate rapidly.
Should I open the windows during a tornado to
reduce resistance and pressure on the building?
This is a myth, and can cost you precious time.
How is the strength of a tornado measured?
The National Weather Service uses something called the
Enhanced Fujita Scale, which incorporates 28 subjective
damage indicators to estimate the wind speed of a
tornado. Ratings range from EF0 to EF5. An EF0 rating,
for instance, estimates the tornado had a 3-second wind
gust of 65 to 85 mph. An EF5 means the wind speed
likely reached over 200 mph. Any tornado, no matter
how “weak,” can kill or cause damage, however.
Where is “Tornado Alley”?
The area for which this nickname is used changes
depending on who is defining it. It’s basically a region
covering several central U.S. states where tornadoes
occur frequently. Some maps measure all tornadoes;
some measure only exceedingly strong ones, and
some use different time periods as their base. What’s
important to know is that tornadoes can occur
anywhere in the U.S., day or night, at any time of year.
Are alert systems keeping up with technology?
There are several apps that relay National Weather
Service tornado warnings to smartphones. Also, the
National Oceanic and Atmospheric Administration
(NOAA), which includes the National Weather Service,
partners with major cellular service providers to push
“Wireless Emergency Alerts” — including tornado
warnings — to most cellphones.
Should I hide in the southwest corner of the
basement?
This is another myth. A structural collapse can affect
any area, and debris can be blown into any corner. Plus,
tornadoes can arrive from any direction, and can even
backtrack after initially going in one direction.
How do tornadoes form?
A tornado needs moisture, unstable air masses, lift
and vertical wind shear. Changes in wind direction and
increasing wind speeds create a horizontal spinning
effect in the lower atmosphere. During a thunderstorm,
an updraft tilts the rotating air into a vertical position
over an area of 2 to 6 miles wide. Most tornadoes form
from this area of strong rotation.
How can a tornado destroy one house, yet leave
the one next door unscathed?
A subvortex within a tornado could be stronger and
more intense, and thus inflict more damage than the
winds in most of the tornado. Differences in structural
integrity could be a factor as well.
Isn’t my town protected by the hill/river?
No. Tornadoes can and have crossed rivers of all sizes,
including the Mississippi, as well as high elevations in
several mountain ranges.
INTERESTING FACTS:
• Oklahoma City has been hit by more than 100
tornadoes.
• A 2013 tornado near El Reno, Oklahoma, was
measured at 2.6 miles wide at its peak.
• A tornado near Bridge Creek, Oklahoma, in 1999
included wind speeds of about 302 mph.
• The record for tornadoes in one month, since
recordkeeping began in 1950, is 817 in April 2011.
• The most costly tornado was the EF5 that hit Joplin,
Missouri, in 2011. It caused an estimated $2.8 billion
in damage.
This severe storm information guide was presented by DKI Services, a nationwide disaster remediation and restoration company that
offers emergency restoration services for residential and commercial buildings.
A WHAT TO DO IF THERE IS
A TORNADO CHECKLIST