Thunderstorms: What You Need to Know
What Is a Thunderstorm?
Thunderstorm Facts:
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How Does a Thunderstorm Form?
• Three basic ingredients are required for a thunderstorm to form:
1.
2.
3.
The Thunderstorm Life Cycle
Developing Stage
Mature Stage
Dissipating Stage
Types of Thunderstorms
• Single cell storm
• Multicell cluster storm
• Supercell thunderstorm
Single Cell Storm
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Thunderstorm Hazards
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Lightning Safety
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Downbursts
An exceptionally strong downdraft that diverges horizontally as a surge of
potentially destructive winds. Most hazardous to aircraft.
Flash Flood Safety
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Hail
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Tornadoes
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Thunderstorms: What You Need to Know
What Is a Thunderstorm?
•
A thunderstorm is a rain shower during which you hear thunder.
Since thunder comes from lightning, all thunderstorms have
lightning. A thunderstorm is classified as "__________" when it
contains one or more of the following: __________________ or
greater, winds in excess of _______ mph or a _________.
Thunderstorm Facts:
• An average thunderstorm is ______ miles in diameter and lasts an
average of _____minutes.
• 2,000 thunderstorms in progress daily around the world
• 100,000 thunderstorms globally each year
• 10,000 become severe
• 1,000 spawn ____________.
How Does a Thunderstorm Form?
• Three basic ingredients are required for a thunderstorm to form:
– moisture
– rising __________ air (air that keeps rising when given a nudge), and
– a ___________ mechanism to provide the "nudge."
The Thunderstorm Life Cycle
Thunderstorms have a life cycle of
_____ stages: The developing stage,
the mature stage, and the _________
stage.
Developing Stage
Marked by a cumulus cloud that is being pushed ___________ by a rising
column of air (updraft). The cumulus cloud soon looks like a _____ (called
towering cumulus) as the updraft continues to develop. There is little to no
___ during this stage but occasional lightning. The developing stage lasts
about ____minutes.
Mature Stage
The ____________________ the storm, but __________ begins to fall out
of the storm, and a ________ begins When the downdraft and rain-cooled
air spreads out along the ground it forms a gust front, or a line of gusty
winds. The mature stage is the most likely time for ____, heavy rain,
frequent ________, strong winds, and tornadoes. The storm occasionally
has a ____________________ appearance.
Dissipating Stage
Eventually, a large amount of precipitation is produced and the _______ is
overcome by the ________beginning the dissipating stage. At the ground,
the gust front moves out a long distance from the storm and cuts off the
warm moist air that was _______ the thunderstorm. Rainfall _________ in
intensity, but lightning remains a danger.
Types of Thunderstorms
• Single cell storm
• Multicell cluster storm
• Supercell thunderstorm
Single Cell Storm
• Single cell thunderstorms usually last between 20-30 minutes. A true
single cell storm is actually quite rare because often the gust front of
one cell triggers the ________________.
• Most single cell storms are not usually severe. However, it is possible
for a single cell storm to produce a brief severe weather event.
Thunderstorm Hazards
•
•
•
•
•
Lightning
Downbursts
_______________
Hail
Tornadoes
Lightning Safety
•
•
•
•
Go inside a structure, a __________, a cave…
If you are outside and your ________________, crouch down,
but do not lie down.
Stay away from _________ of all kinds.
If you can hear thunder, you are _______ enough to get struck
by lightning. It doesn’t have to be raining at your site.
Downbursts
An exceptionally strong downdraft that diverges horizontally as a surge of
potentially destructive winds. Most hazardous to aircraft.
Flash Flood Safety
•
•
•
•
Floodwaters only ____________ can carry away most cars.
Watch where you camp.
Never cross a stream deeper than your knees.
_____________ your car if it stalls, and seek higher ground.
Hail
• Falls from _____________clouds.
• Largest recorded was 5.5 inches in diameter (softball size).
• Most damage occurs to ________. Can _________________ and
smash windows.
• _____________ by all thunderstorms.
Tornadoes
•Will discuss in our next section
Thunderstorms: What You Need to Know
What Is a Thunderstorm?
•
A thunderstorm is a rain shower during which you hear thunder.
Since thunder comes from lightning, all thunderstorms have
lightning. A thunderstorm is classified as "severe" when it
contains one or more of the following: hail three-quarter inch or
greater, winds in excess of 57.5 mph, tornado.
Thunderstorm Facts:
• An average thunderstorm is 15 miles in diameter and lasts an average
of 30 minutes.
• 2,000 thunderstorms in progress daily around the world
• 100,000 thunderstorms globally each year
• 10,000 become severe
• 1,000 spawn Tornadoes
How Does a Thunderstorm Form?
• Three basic ingredients are required for a thunderstorm to form:
– moisture,
– rising unstable air (air that keeps rising when given a nudge), and
– a lifting mechanism to provide the "nudge."
The Thunderstorm Life Cycle
Thunderstorms have a life cycle of
three stages: The developing stage,
the mature stage, and the dissipating
stage.
Developing Stage
Marked by a cumulus cloud that is being pushed upward by a rising
column of air (updraft). The cumulus cloud soon looks like a tower (called
towering cumulus) as the updraft continues to develop. There is little to no
rain during this stage but occasional lightning. The developing stage lasts
about 10 minutes.
Mature Stage
The updraft continues to feed the storm, but precipitation begins to fall out
of the storm, and a downdraft begins When the downdraft and rain-cooled
air spreads out along the ground it forms a gust front, or a line of gusty
winds. The mature stage is the most likely time for hail, heavy rain,
frequent lightning, strong winds, and tornadoes. The storm occasionally
has a black or dark green appearance.
Dissipating Stage
Eventually, a large amount of precipitation is produced and the updraft is
overcome by the downdraft beginning the dissipating stage. At the ground,
the gust front moves out a long distance from the storm and cuts off the
warm moist air that was feeding the thunderstorm. Rainfall decreases in
intensity, but lightning remains a danger.
Types of Thunderstorms
• Single cell storm
• Multicell cluster storm
• Supercell thunderstorm
Single Cell Storm
• Single cell thunderstorms usually last between 20-30 minutes. A true
single cell storm is actually quite rare because often the gust front of
one cell triggers the growth of another.
• Most single cell storms are not usually severe. However, it is possible
for a single cell storm to produce a brief severe weather event.
Thunderstorm Hazards
•
•
•
•
•
Lightning
Downbursts
Flash floods
Hail
Tornadoes
Lightning Safety
•
•
•
•
Go inside a structure, a vehicle, a cave…
If you are outside and your hair stands on end, crouch down,
but do not lie down.
Stay away from metal of all kinds.
If you can hear thunder, you are close enough to get struck by
lightning. It doesn’t have to be raining at your site.
Downbursts
An exceptionally strong downdraft that diverges horizontally as a surge of
potentially destructive winds. Most hazardous to aircraft.
Flash Flood Safety
•
•
•
•
Floodwaters only 18” deep can carry away most cars.
Watch where you camp.
Never cross a stream deeper than your knees.
Abandon your car if it stalls, and seek higher ground.
Hail
• Falls from cumulonimbus clouds.
• Largest recorded was 5.5 inches in diameter (softball size).
• Most damage occurs to crops. Can dent automobiles and smash
windows.
• Not produced by all thunderstorms.
Tornadoes
•Will discuss in our next section