What are the weather conditions shown in this synoptic chart?
It is showing a summer anticyclone. We can see high pressure (pressure over 1000) and clockwise winds. Typically in this conditions the air mass is Tropical Continental - warm and dry winds from places like the Sahara. We can see no rain as in summer anticyclones we do not see much cloud formation as it is high pressure.There are light winds over England and Eastern Europe - we can see this through the knots and gap between the isobars. However Scotland an Ireland have higher wind speeds and more cloud cover.
There is also an occluded front passing over this part of the UK - traditionally we do not see front in anticyclonic conditions- but just goes to show the weather isn't as simple as the textbook suggests. The occluded front occluded front occurs where a warm front and a cold front meets. the means the amount of warm air that rises is larger than just a warm or cold front. This means that in that area there will be a down pour of torrential rain possibly.
What is an extreme weather event?
It is severe or unusual weather conditions e.g. hurricanes which causes severe impacts on the environment, economy and people.
So what are the risks associated with this weather system?
- As temperatures can become extremely high we will see many health risks of dehydration etc and this worst affects the elderly and the young.
- Water levels can become extremely low which means hydroelectric power and thermal power station may have to shut as the cooling process becomes impossible.This is dangerous because it is in a time when people will need Air conditioning in their homes.
- Once again there is a high risk of fog, which is hard to forecast, and this may cause breathing difficulties. Especially because pollution can get caught in sinking air causing smog - which is terrible for asthmatics.
- In extreme event 'blocking highs' can occur where the normal pattern of weather is diverted and we are stuck with the anticyclone for long periods of time.
For a real life example look at my post on the EU heatwave in 2003.