1. Mid-Latitude Weather Systems
Bring our weather particularly in autumn to spring
Satellite image and weather map
Swirl of cloud
Well developed depression
Circular pattern of isobars, cold and warm fronts, low pressure
How do these develop and what role do they play in the circulation of the Earths atmosphere
Last of order 3 days
Scale and duration
Low Pressure System = Mid - Latitude Depression = Cyclone

2. 2013/ 2014
Stormiest period of weather experienced by the UK for 143 years
12 major winter storms affecting the UK, from mid-December to early January and late January to mid-February
Wettest winter in England and Wales since 1766
December 2013 was the wettest month since 1910
Fewest air frosts since 1961
All to do with depressions

3. And some things will never be the same
again
Porthcothan Bay, Cornwall
Porthreath, Cornwall

4. What governs the damage caused by a depression?
The pressure difference, which in turn determines the wind speed
Time of year – are trees in leaf or not?
Preceding weather – is the ground waterlogged or not?
The path of the storm
The time of the month – spring or neap tide
Forecast accuracy

5. 28th October 2013 St Jude Storm
It was the first of the storms and at the time was compared with the 1987 storm, but actually it was nowhere near as destructive
Comparison with 1987 storm
Images and a report
Met Office Summary

6. 5th December 2013 Storm Bodil/ Sven/ Xaver
Before the UK/ Ireland had a storm naming convention – this storm was given different names by different countries.
It had the biggest impact on us when the centre of the Low was over Scandinavia.
Remember that the wind follows the isobars and blows around a Low in an anticlockwise direction. The wind is blowing down the North Sea from the North.
The wind carries with it some of the surface water.
Look at the width of the N Sea – it starts wide and narrows as you go south. As the water is blown south, it is funnelled into an ever smaller area, and so the sea level has to rise.
Storm surge explanation

7. When pressure falls by one millibar, sea level rises by one centimetre
In addition, when pressure falls by one millibar, sea level rises by one centimetre.
Thirdly, the 5th December was a time of a spring tide.
These 3 factors together gave extremely high water levels, with many places on the east coast of England flooded.
When pressure falls by one millibar, sea level rises by one centimetre
Worst tidal surge in 60 years. Thames Barrier saved London.

8. 2015 – Named Storms Barney Abigail
Storm Abigail brought heavy rain and strong winds across the country with the most severe weather impacting the northwest of Scotland where power cuts affected up to 20,000 homes and many schools were forced to close for the day.
Named Storms – criteria - A storm will then be named when it is deemed to have the potential to cause substantial impacts in the UK and/or Ireland.
Clodagh
Desmond
Devastating flooding in Cumbria and parts of Lancashire
As forecast, the impacts of Clodagh were most severe in the Republic of Ireland as gusts of more than 70 mph leaving 3,500 people without electricity.
The strong winds caused transport disruption and cancellations with fallen trees blocking roads and railway lines in the North of England and several cancellations in across Scotland