Professionals - Storms - Prevention

1. E-Learning for Storms
Professionals

2. Prevention
In the following you will be provided with information on:
• What is a storm
• How to recognise the signs or warnings
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Kevin Wadsworth, The Met Office

3. Prevention
Storms are a natural
phenomenon which cannot be
prevented, but you can be
more aware and better
prepared if you are affected.
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© Copyright David Stowell and licensed for reuse under the Creative Commons
Licence.

4. What is a storm?
Definition
• A storm is any disturbed state of an environment or astronomical
body’s atmosphere especially affecting its surface, and strongly
implying severe weather.
• Storms are created when a centre of low pressure develops with a
system of high pressure surrounding it. This combination of
opposing forces can create winds and result in the formation of
storm clouds, such as cumulonimbus. Small localised areas of low
pressure can form from hot air rising off hot ground, resulting in
smaller disturbances such as dust devils and whirlwinds.
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5. What is a storm?
Definition
• Wind is air that is in motion. The
sun heats the Earth’s surface. As
the Earth’s surface heats, so does
the atmosphere. Some parts of the
Earth receive more direct heat
and stay warmer (i.e. land) while
others are cooler (i.e. water).
Warm air weighs less than cool
air and so it rises. As it does,
cooler more dense air replaces the
risen warmer air. The movement
of that air is what causes wind.
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Source: NOAA

6. What is a storm?
For further information on weather systems, please refer to the
following:
• MetOffice - How Weather Works - Pressure
• MetOffice - How Weather Works - Wind Flow
• MetOffice - Highs and Lows - Weather Conditions
• Video – click next slide
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7. What is a storm?
When is a wind a storm?
• The Beaufort Scale is an empirical
measure for describing wind
intensity based on observed
conditions at sea or on land.
• A strict meteorological definition
of a terrestrial storm is a wind
measuring 10 or higher on the
Beaufort scale. Storms can last
anywhere from 12 to 200 hours,
depending on season and
geography.
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Beaufort
1-min Wind
speed
Effects on land
0
Calm
0 - 1 mph Calm. Smoke rises vertically.
1
Light air
1 - 3 mph
Smoke drift indicates wind direction and wind vanes cease
moving.
2
Light breeze
3 - 7 mph
Wind felt on exposed skin. Leaves rustle and wind vanes
begin to move.
3
Gentle breeze
7 - 12 mph
Leaves and small twigs constantly moving, light flags
extended.
4
Moderate
breeze
12 - 17 mph Dust and loose paper raised. Small branches begin to move.
5
Fresh breeze
17 - 24 mph
Branches of a moderate size move. Small trees in leaf begin
to sway.
6
Strong breeze
24 - 30 mph
Large branches in motion. Whistling heard in overhead wires.
Umbrella use becomes difficult. Empty plastic bins tip over.
7
Near gale
30 - 38 mph Whole trees in motion. Effort needed to walk against the wind.
8
Gale
38 - 46 mph
Some twigs broken from trees. Cars veer on road. Progress
on foot is seriously impeded.
9
Severe gale
46 - 54 mph
Some branches break off trees, and some small trees blow
over. Construction/temporary signs and barricades blow over.
10
Storm
54 - 63 mph
Trees are broken off or uprooted, saplings bent and deformed.
Poorly attached asphalt shingles and shingles in poor
condition peel off roofs.
11
Violent storm
63 - 73 mph
Widespread damage to vegetation. Many roofing surfaces are
damaged; asphalt tiles that have curled up and/or fractured
due to age may break away completely.
12
Hurricane
73 - 99 mph
Very widespread damage to vegetation. Some windows may
break; mobile homes and poorly constructed sheds and barns
are damaged. Debris may be hurled about.

8. What is a storm?
Clouds
• As indicated earlier, the causes of wind also result in the formation
of clouds. Clouds are formed when a mass of warm air rises up over
a mass of cold air. The range of ways in which clouds can be formed
and the variable nature of the atmosphere results in an enormous
variety of shapes, sizes and textures of clouds.
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9. What is a storm?
Clouds
• The following cloud types are associated with storms or severe weather:
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Cumulonimbus Clouds
Cumulonimbus clouds are heavy
and dense low-level clouds,
extending high into the sky in
towers, plumes or mountain
shaped peaks. The base is often
flat and very dark, and may only
be a few hundred feet above the
Earth’s surface. Cumulonimbus
clouds are associated with
thunderstorms and atmospheric
instability. These clouds are
capable of producing lightning
and other dangerous severe
weather.
Nimbostratus clouds
Nimbostratus clouds are dark
grey or bluish grey featureless
layers of clouds, thick enough
to block out the sun. These
mid-level clouds are often
accompanied by continuous
heavy rain or snow and cover
most of the sky. If there is
hail, thunder or lightning it is
a cumulonimbus cloud rather
than nimbostratus.
Funnel Clouds
A funnel cloud is a cone-
shaped cloud which extends
from the base of a cloud
towards the ground without
reaching the ground. They
are formed in the same way
as a tornado, building around
a localised area of intensely
low pressure and are typically
associated with the formation
of cumulonimbus clouds

10. What is a storm?
Clouds
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Cumulonimbus Clouds Nimbostratus clouds Funnel Clouds
© Copyright Richard Croft and licensed for reuse under the
Creative Commons Licence.
Source: Met Office © Copyright Tony Atkin and licensed for reuse under the Creative Commons Licence.

11. What is a storm?
For further information on clouds, please refer to the following:
• MetOffice - Learning - Clouds
•
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Source: NOAA

12. Types of storm
There are many varieties and names for storms. Here are some of the more common ones:
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Thunderstorm
A storm that generates lighting
and the attendant thunder. It is
normally accompanied by heavy
precipitation.
Source: Kevin Wadsworth, The Met Office

13. What is a storm?
For further information on thunderstorms, please refer to the
following:
View next slide
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14. Types of storm
There are many varieties and names for storms. Here are some of the more common ones:
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Snowstorm
A heavy fall of snow
accumulating at a rate of more
than 5 centimetres (2 inches) per
hour that lasts several hours.
© Copyright David Stowell and licensed for reuse under the Creative Commons Licence.

15. Types of storm
There are many varieties and names for storms. Here are some of the more common ones:
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Blizzard
A blizzard is accompanied by
gale-force winds, heavy snow,
accumulating at a rate of at least
5 centimetres (2 inches) per
hour, and very cold conditions
(approximately -10 degrees
Celsius or 14 F).
© Copyright Andy Dolman and licensed for reuse under the Creative Commons Licence

16. Types of storm
There are many varieties and names for storms. Here are some of the more common ones:
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Wind storm
A storm marked by high wind
with little or no precipitation.
High winds are also the cause of
Storm Surge, Dust Storms and
Sand Storms in dry climates.
(refer to Beaufort Scale).
© Copyright David Baird and licensed for reuse under the Creative Commons Licence

17. Types of storm
There are many varieties and names for storms. Here are some of the more common ones:
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Hailstorm
A type of storm that precipitates
round chunks of ice. Hailstorms
usually occur during regular
thunder storms. There are
occasional occurrences of hail
greater than 5cm (2 inches) in
diameter that can cause damage
and injury.
© Copyright Mat Fascione and licensed for reuse under the Creative Commons Licence

18. Types of storm
There are many varieties and names for storms. Here are some of the more common ones:
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Tropical Cyclone
A tropical cyclone is a storm system with a closed circulation around a centre of
low pressure, fuelled by the heat released when moist air rises and condenses.
Tropical cyclones are distinguished from other cyclonic storms, such as nor’easters
and polar lows, by the heat mechanism that fuels them, which makes them “warm
core” storm systems. Tropical cyclones form in oceans if the conditions in the area
are favourable and, depending on their strength and location, there are various
terms by which they are called, such as tropical depression, tropical storm,
hurricane and typhoon.

19. Types of storm
There are many varieties and names for storms. Here are some of the more common ones:
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Tropical Cyclone

20. What is a storm?
For further information on tropical cyclones, please refer to the
following:
View next slide
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21. Types of storm
There are many varieties and names for storms. Here are some of the more common ones:
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Tornado
A tornado is a violent, destructive wind storm
occurring on land. Usually its appearance is that
of a dark, funnel-shaped cloud. Often tornadoes
are preceded by a thunderstorm and a wall cloud.
They are often called the most destructive of
storms, and while they form all over the world, the
interior of the United States has the most prone
areas, especially throughout Tornado Alley.
Commons Wikimedia

22. What is a storm?
For further information on tornadoes, please refer to the following:
• MetOffice - How Tornadoes are Formed
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23. The impacts of storms
Storms result in numerous weather-related impacts both inland and around the coast.
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24. The impacts of storms
Storms result in numerous weather-related impacts both inland and around
the coast. Examples include:
• Widespread flooding
• Major disruption to transport including travel by road, rail, sea and air
• Power cuts and loss of other utilities
• Damage to critical infrastructure
• Damage to homes, businesses and vehicles
A prime example of where these impacts are felt in combination is during
storm surges.
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25. The impacts of storms
Storm Surge
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Strong winds, high tides and tidal surges acting in combination create huge waves,
known as a storm surge.
Met Office
These storms can cause damage to sea vessels, sea defences and infrastructure and
lead to flooding to properties and disruption to road and rail travel along the coast.

26. The impacts of storms
1953 east coast flood
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During the night of 31 January 1953 and morning of Sunday 01 February, a storm
in the North Sea caused a storm surge which coincided with a high spring tide.
The flood struck the east coast of England and Scotland, as well as the Netherlands
and Belgium. Although the storm and surge were forecast in advance, public
warning systems were not effective at that time as local radio stations did not
broadcast at night, and many people were not prepared for the flooding. More
than 2,500 people were killed around the North Sea coastline (1,836 in the
Netherlands, 307 in England, 28 in Belgium, 19 in Scotland and 361 out at sea).
Around 30,000 animals were drowned and, as well as loss of life, the flooding
caused massive damage to people’s homes and businesses and ruined large areas of
farmland.

27. The impacts of storms
1953 east coast flood
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For more information on the 1953 east coast
flood, please refer to:
MetOffice - News - 1953 East Coast Flood

28. The impacts of storms
Winter storms, December 2013 to February 2014
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The 2013/2014 United Kingdom winter floods saw areas of the United Kingdom inundated following severe
storms. The south of England saw heavy rainfalls associated with these storms which caused widespread
flooding, power cuts and major disruptions to transport. Economically the worst affected areas were
Somerset, Devon, Dorset and Cornwall in the south west and the Thames Valley in the south east. The flood
phenomena ranged from coastal flooding, pluvial flooding, fluvial flooding to groundwater flooding. The
flooding resulted in the inundation of the majority of the Somerset Levels and saw the main railway line to
Cornwall and West Devon severed by the sea at Dawlish.
The storms and strong winds also caused widespread impacts inland. Many trees were felled by the wind and
on 12 February around 100,000 homes and businesses were without power. Several buildings experienced
structural damage by winds. The Met Office issued a Red Warning for wind – the highest level of warning –
for parts of North Wales and north-west England for the storm on 12 February 2014, while at the height of
the storms more than 15 severe flood warnings were in place across the country.

29. The impacts of storms
Winter storms, December 2013 to February 2014
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Smalljim © Copyright Steven Craven and licensed for reuse under the
Creative Commons Licence
© Copyright Noel Jenkins and licensed for reuse under the Creative
Commons Licence

30. The impacts of storms
Europe snowstorm, February 2015
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Snowfall and heavy rain affected large parts of Europe and brought deadly floods to the Balkans. In the
Balkans at least 600 families were evacuated due to flooding and thousands of livestock were believed to be
killed.
In Croatia and Slovenia, heavy snowfall caused authorities to place travel bans on major roads. 120kph gale
force winds disrupted border traffic in Slovenia, where borders were closed to trucks.
Over 200 drivers in Spain had to be rescued from their vehicles by emergency services, due to snowdrifts, and
some rail services were also suspended. Italy was also forced to close major highways amid severe snowdrifts.
Eastern Macedonia and parts of Greece were placed under a state of emergency.
Storm surge and tidal flooding were also observed in Venice, Italy.

31. What is a storm?
For further information on other high profile weather events that have
affected the UK in recent times, please refer to the following:
• MetOffice - Case Studies
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32. The impacts of storms
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Although the impacts of these events were caused by strong winds and
storm surges, similar impacts can be felt through other storms, such as
thunder, snow and hail storms.
It should also be noted that although storms generally lead to negative
impacts on lives and property, systems with significant rainfall can
alleviate drought in places they move through.
Heavy snowfall can also allow special recreational activities to take
place, which would not be possible otherwise, such as skiing.

33. Further information
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You can learn more about weather, storms and their impacts via the
following websites:
• www.metoffice.gov.uk
• www.gov.uk/government/organisations/environment-agency

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