Can a winter anticyclone be classed as an extreme weather event?

What are the weather conditions shown in this map?

Firstly there is an winter anticyclone. The pressure is over 1000 (high pressure) and winds are blowing in a clockwise direction. There is also quite a large gap between isobars showing winds aren’t that high which fits in the model of a winter anticyclone. There will be hardly any clouds allowing the sun to shine through although the temperatures will still be low as there is a lack of clouds which allows heat to escape back into the atmosphere. We can see this through the symbols on the chart. The winter anticyclone has built up through cold and dry condition in Scandinavia and Eastern Europe. The Polar Continental air mass is the main one associated with this weather system.

There is also a cold front passing through North East England and Scotland. Traditionally, in anticyclonic conditions we do not see fronts forming but it just goes to show that real weather is much more complex than what the textbook says. In this front the cold air advances and force the warm air to rise sharply.

When the warm air rises quickly is condenses and causes a short rapid snap of heavy rain. Hence around the front we see symbols of rain.

What is an extreme weather event?

It is severe or unusual weather conditions e.g. hurricanes which cause severe impacts on the environment, people and economy.

So what are the risks with this condition?

  1. Firstly, temperatures can become extremely low bringing many health risks like hypothermia especially to children and the elderly.
  2. Many who suffer with breathing difficulties will probably have many problems. This is because first off the air is cold and dry and secondly there is a high risk or fog which is known to making breathing difficulties bigger.
  3. Fog is difficult to forecast in these situations do to cloud cover or the lack of it! This makes forecasting difficult and when extreme anticyclonic conditions are arising it is hard to forecast hence hard to act appropriately.
  4. Some extreme situations see heavy snow of ice falling. As we have seen in the last too months this can cause severe disruption. Many lives are lost, over a million people are not able to reach work and livestock are dying as they are not able to cope with these cold conditions.


Can a depression be classed as an extreme weather event?

Describe how the depression shown on this chart might produce extreme weather hazards.
What is an extreme weather event?
It is severe or unusual weather conditions e.g. hurricanes which cause severe impacts on the environment, people and economy.
What are the weather conditions shown in this map?

Firstly there is a depression. The pressure is below 1000mb (low pressure) and winds are blowing in an anti-clockwise direction. There is also quite a small gap between isobars showing winds are strong which fits in the model of a depression. There will be a large cloud cover as a depression is when warm air meets could air and this causes the warm air to cool resulting in precipitation. The depression has built up through cold and wet conditions in the Arctic Ocean. The Polar Maritime air mass is the main one associated with this weather system.
There is also a cold front passing through South East of England. Traditionally, in low pressure conditions we see occluded fronts forming on the actual land but even if it is close there will still be torrential rain on land. In this front the cold air advances and force the warm air to rise sharply. The result of a cold front is a rapid period of torrential rain.
So what are the risks with this condition?
    1. Firstly, temperatures can become extremely low bringing many health risks like hypothermia especially to children and the elderly.
    2. Torrential rainfall can lead to river flooding which especially with cold fronts lead to flash floods. The can cause many adverse effects  for example the Boscastle 2004 flash floods caused injuries, £2 million damage to buildings and roads and coastal pollution as debris and fuel from cars flowed out into the sea.
    3. In extreme situations could lead to a snowstorm or blizzard which as we saw in February 2009 causes disruptions and deaths.
    4. It could lead to high waves and surge may be destructive to the coast.
    5. In the case of flooding if sewage systems failed then they would be a risk of cholera and other disasters.

Contending with Extreme Weather

How can we best respond to and cope with the impacts of extreme weather?

Key idea: Adaptation vs. Mitigation 

Extreme weather can bring some very adverse impacts onto area socially, economically and environmentally. So there are ways of dealing with it. We can either adapt to the situation or mitigate. Adaptation is usually used in  these event because these event are either caused by complex human causes such as climate change or natural such as the Milankovitch cycles which are hard to mitigate. Below I have defined each term as it is important to  understand them:

Adaptation: Any change in the structure or functioning of an organism or system that makes it better suited to the environment. For example; Boscastle is a flood prone village thus they have changed the shape of the river so it can hold of more water and cutting the impacts of flooding – not causes.

Mitigation: The process by which you make something less harmful or serious. For example; it is claimed the European heatwave in 2003 was caused by climate change. So people governments have got together like in the Copenhagen  treaty to discuss how we can cut carbon emission to mitigate climate change.

Key concept: Short-term strategies vs. long-term strategies 

Short-term strategies used to contending with difficulties with extreme weather can include increasing the number of medical staff around or evacuating people from a certain area. LEDCs tend to rely ons short-term strategies as they cannot around long-term strategies and they also rely on foreign aid for the short-term strategies.

Long-term strategies tend to be hard engineering and quite costly. The work in reducing the impacts in the long term. So for example to reduce the impact of cars being swept away by floods, Boscastle raised the level of the car park and added extra barriers to it.

How was Hurricane Katrina predicted?

Wind speed and temperature across hurricane forming regions are measured with satellites.On these satellites we can even see the cloud formation and swirling winds. From these meteorologists can predict hurricanes. Hurricane Katrina was predicted accurately 6 days before. The official hurricane forecasting organisation is the ‘National Hurricane Centre’.(Link: )
The hurricane was so violent that people were commanded to evacuate. However, 20% of the population (low income groups) didn’t have their own private transport or due to financial reasons were not able to evacuate and were left stranded in the disaster.

What did strategies did the environmental agency take in Boscastle?

They went for 4 long-term hard engineering strategies to reduce the impacts of flooding. 
  1. The environmental agency made a decision to lay a large relief culvert that would carry excess rainwater. It is twice the size of the old one. 
  2. The River Valency is being widened and lowered from the lower bridge to the car park, so that it has a bigger capacity and can carry more water.
  3. The height of the car park is being raised using stone removed from the river bed. Also barriers are being made for the car park so that if it floods it takes much longer for the cars to be swept away.
  4. There are plans to demolish the lower bridge near the harbour and replace it with a higher bridge further downstream. This will give the river more capacity and help to reduce flooding.

Risk assessment 
Risk assessment is way in which organisations such as the environmental agency can decide whether certain solutions are suitable to the particular hazards.
Boscastle flood risk assessment is done by a method called recurrence interval. It is a graph which displays the probability of floods of different levels occurring. The 2004 flash flood had a 1 in 400 years chance of coming. This does not mean the next one this big will happen after 400 years it could happy after a month and then not happen for 800years. Therefore, it isn’t particularly accurate.

Role of Technology 

As technology advances we are able to predict events faster and more accurately and we are able to find solutions which are more smart and suited to our environments.
So for example in the case of Hurricane Katrina the National Hurricane Centre were able to use new satellites to predicted accurately the hurricane would come in 6 days and help the resident of the New orleans prepare for it.

The met office use technology to forecast weather and throughout time the technology has become more efficient and accurate. For example, the snow we experienced in December 2009 and January 2010 the met office were able to give severe warnings about.

Technology is also used to reduce the impacts if disaster. River Flooding can be a great disaster and in a city like London if there was a big flood so much would be destroyed. With technology engineers were able to create the Thames Barrier which has helped reduce the risk of flooding.

GIS (geographical information systems) is a complex computer system which will show you the geography of an area including demo-graph, physical landscape and buildings in an area. They can be used for flood monitoring because they can monitor flood levels and with the weather forecast; meteorologists can put 2 and 2 together to prepare for a flood.

In extreme heat event like drought technology has been useful here as well because through genetic modification we have been able to create drought resistant crops which means that even in the worst conditions farmers will still have agricultural goods to distribute.

National Oceanic and Atmospheric Administration

NOAA is a similar organisation to the met office and national hurricane centre. They forecast weather, give warning and advice people of coping methods. They use the latest technology and produce some very accurate results. Check their about me section out:

GIS & Technology in Meteorology

What is a GIS?

Geographic information systems are software tools and digital maps that allow users to create interactive queries (user created searches), analyse spatial information, edit data, maps etc.It can help with assessing current and future scenarios. In a GIS software you can switch layers on and off allowing one to see different scenarios and evaluate different data. They can be used to prepare mathematical models for extreme weather forecasting because it can process complex spatial information unlike other electronic devices.

Examples of geographic information systems:

  • Google Earth
  • Kalypso
  • Capaware
  • FalconView

What are these softwares used for?

  1. Risk analysis of weather hazards i.e. land users near hazard prone areas and the effect of different management strategies upon them.
  2. To identify people/groups and properties at risk from different magnitudes of extreme weather events. This is particularly useful for insurance companies too.
  3. To identify possible impacts of climate change for example, modelling increased rainfall intensity and frequency or higher temperatures.This includes other scientific investigations which it is used for.
  4. Helping decisions of what sort of management should take place in an area. It can help decide which location would be the most effective and what form defences should be put in place i.e. hard engineering or soft engineering.
  5. The software can help various agencies involved in the supply of services such as water, telecommunication, electricity, road, hospital etc. to understand the potential risks and impacts of extreme weather linked directly to their facilities and infrastructure.
  6. Can help organisations such as the Environmental Agency plan weather warning systems and identify the groups of population with the most risk.

The role of technology in metrology 

Technology has lets us become very precise and efficient in planning, preparing and managing with extreme weather conditions. We can now predict hazards accurately; for example Hurricane Katrina was predicted accurately 6 days before the event by the National Hurricane Centre. As well as that, we are able to protect ourselves from these hazards for example the Thames Barrier protects parts of London from being flooded.

So what new technology do we have today?

  1. We have better computer modelling softwares which aids us in forecasting locations, durations and likely impacts of extreme weather. An example of this is GIFS (Global Interactive Forecasting System) which uses advance grid computation technology.
  2. Weather radar data can help us forecast precipitation. It uses Doppler radar to accurately measure wind speed in severe storms and precipitation over large area of land.
  3. Satellites are good with forecasting hurricanes and floods. They are used to estimate the rate of rain etc.
  4. GIS as mentioned above can be used to prepare mathematical models for extreme weather forecasting because it can process complex spatial information.
  5. We can measure droughts and storms and predict how long they will be around by examining pressure with new aneroid barometers and satellites.
However important the role of technology; it can sometimes be hard to implement it in vulnerable communities because they do not have the technical capacity locally and many people may not have the skills to use it. The cost of training staff and the cost of technology itself can be a problem for some of the most affected parts of the world. There could also be issues with the standardisation of information across agencies and countries.


Case Study: Snowstorm Feb 2009

This case study was commonly described as ‘Arctic conditions’ – Occluded Front.
It is extreme weather event because the weather experienced was severe and it was an unusual weather condition and it is believed to happen every two to three decades. This hazard brought freezing blizzards particularly in the South East.




Dates; 1-13th Feb
Type of snow; Wet snow
Maximum depth; 55cm (or 22 inches),  It was the heaviest snowfall for 18 years.




  • Warm air mass from France and cold air mass from Arctic clashed. This rare reversal in winds brought heavy snowfall. Basically an anticyclone clashed with a depressions. High pressure from France clashed with low pressure from the Arctic.
  • An occluded front formed
  • Some scientists suggest this could be cyclical; 1 in 20 years.
  • Some say that if it was cyclical then we are experiencing less and less of this type of weather, from 1 every 5 years it seems to be 1 every 20 years. This might be the invisible hand of climate change
  • 20% of all employees (6.4 million) failed to show up at work
  • It cost £1.2 billion
  • Online commerce received a boost especially carrot sales
  • Mobile phone circuits disrupted
  • Sat Navs systems (GPS) could not receive satellite signal
  • Roads were closed and infrastructure failed
  • Emergency services such as ambulances found it hard to reach victims
  • The build up of ice and snow on the Severn Bridge meant that dangerous chunks of ice and snow were falling hence the gateway to Wales had to shut down for two days.
  • 4 climber lost their life in Snowdonia
  • Gatwick Airport temporarily closed
  • Cornwall experience a vortex of wind similar to a tornado
  • Many plants and animals could not cope and died
  • One day suspension of congestion charge
  • Roads were gritted but not fast enough.
  • People questioned why the UK didn’t cope as well as Russia and Canada. They respond with snow tractors, electrical works and even snow chains on their shoes. New York have  all of these and super grit machines to mange. They have snow teams that work around the clock and usually declare a snow day!
  • Why can’t we adapt to snow just as well!
Past experiences
Mid 16th century; A mini ice age was experienced, even though it caused famine people celebrated on the Thames 200 years of a cold snap.
Jan 1947; 6ft deep snow caused famine
March 1963; Heavy snow caused 3 death with a further 2 who suffocated, milk delivery was put to a halt and as a result we experience severe flooding particularly in Blackall.
Feb 1991; soft and powdery snow found its way into electrical systems causing short circuits. It is famously remember as ‘the wrong type of snow’. It made the whole of the transport system stop.