professionals - storms - prevention

E-Learning for StormsProfessionals

e-Learning for the Prevention, Preparedness and Response to Natural Disasters

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PreventionIn the following you will be provided with information on:

• What is a storm

• How to recognise the signs or warnings

Kevin Wadsworth, The Met Office


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PreventionStorms are a natural phenomenon which cannot be prevented, but you can be more aware and better prepared if you are affected.

© Copyright David Stowell and licensed for reuse under the Creative Commons Licence.


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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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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.

Source: NOAA


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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

http://www.metoffice.gov.uk/learning/learn-about-the-weather/how-weather-works/highs-and-lows/pressure

http://www.metoffice.gov.uk/learning/learn-about-the-weather/how-weather-works/highs-and-lows/pressure

http://www.metoffice.gov.uk/learning/learn-about-the-weather/how-weather-works/highs-and-lows/wind-flow

http://www.metoffice.gov.uk/learning/learn-about-the-weather/how-weather-works/highs-and-lows/wind-flow

http://www.metoffice.gov.uk/learning/learn-about-the-weather/highs-and-lows/weather-conditions

http://www.metoffice.gov.uk/learning/learn-about-the-weather/highs-and-lows/weather-conditions


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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.

Beaufort 1-min Wind speed Effects on land

0Calm 0 - 1 mph Calm. Smoke rises vertically.

1Light 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.

3Gentle 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.

5Fresh 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.

7Near gale 30 - 38 mph Whole trees in motion. Effort needed to walk against the wind.

8Gale 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.

10Storm 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.

11Violent 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.

12Hurricane 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.


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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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What is a storm?Clouds• The following cloud types are associated with storms or severe weather:

Cumulonimbus CloudsCumulonimbus 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 cloudsNimbostratus 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 CloudsA 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


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What is a storm?Clouds

Cumulonimbus Clouds Nimbostratus

cloudsFunnel 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.


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

Source: NOAA

http://www.metoffice.gov.uk/learning/clouds

http://www.metoffice.gov.uk/learning/clouds


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Types of stormThere are many varieties and names for storms. Here are some of the more common ones:

ThunderstormA storm that generates lighting and the attendant thunder. It is normally accompanied by heavy precipitation.

Source: Kevin Wadsworth, The Met Office


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What is a storm?For further information on thunderstorms, please refer to the following:View next slide


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SnowstormA 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.


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BlizzardA 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


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Wind stormA 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


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HailstormA 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


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Tropical CycloneA 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.


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Tropical Cyclone


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What is a storm?For further information on tropical cyclones, please refer to the following:View next slide


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TornadoA 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


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What is a storm?For further information on tornadoes, please refer to the following:• MetOffice - How Tornadoes are Formed

http://www.metoffice.gov.uk/learning/learn-about-the-weather/weather-phenomena/tornado/how-tornadoes-are-formed

http://www.metoffice.gov.uk/learning/learn-about-the-weather/weather-phenomena/tornado/how-tornadoes-are-formed


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The impacts of stormsStorms result in numerous weather-related impacts both inland and around the coast.


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The impacts of stormsStorms 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 vehiclesA prime example of where these impacts are felt in combination is during storm surges.


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The impacts of stormsStorm SurgeStrong 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.


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The impacts of storms1953 east coast floodDuring 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.


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The impacts of storms1953 east coast flood

For more information on the 1953 east coast flood, please refer to:MetOffice - News - 1953 East Coast Flood

http://www.metoffice.gov.uk/news/in-depth/1953-east-coast-flood

http://www.metoffice.gov.uk/news/in-depth/1953-east-coast-flood


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The impacts of stormsWinter storms, December 2013 to February 2014The 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.


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The impacts of stormsWinter storms, December 2013 to February 2014

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


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The impacts of stormsEurope snowstorm, February 2015Snowfall 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.


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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

http://www.metoffice.gov.uk/about-us/who/how/case-studies

http://www.metoffice.gov.uk/about-us/who/how/case-studies


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The impacts of stormsAlthough 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.


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

http://www.metoffice.gov.uk/

http://www.gov.uk/government/organisations/environment-agency


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professionals - storms - prevention

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