Storm Emma is causing chaos in the snow-hit UK as it meets the Beast from the East - but why is it named Emma, when we've already had a Storm Eleanor this year?

UK-named storms are in alphabetical order - but Emma was named by the Portugal Met Office as it hit the Azores islands. If a storm has been named by a national meteorogical service, it retains its name as it crosses international borders.

Winter storms have buffeted these shores since the dawn of time, but 2015 was the first year they had official names. After Storm Abigail became the UK's first named storm in November 2015, others came thick and fast, with Desmond, Gertrude and Imogen in particular wreaking havoc across the country during that storm season.

Storms Angus, Barbara, Conor, Doris and Ewan hit the UK during the 2016/17 season. 2017/18 will be the third season where UK storms have names. 

In early January 2018, Storm Eleanor battered Britain with gusts of up to 100mph before Storm Fionn left much of the country under a blanket of snow and temperatures plummeted to -7C.

Storm Georgina hit on January 24, with winds of up to 90mph.

The first named storm of the season, Storm Aileen, brought winds of up to 75mph to parts of the UK in early September, while Storm Brian brought heavy rain and winds up to 70mph to Wales and the south of England on October 21. Storm Caroline brought gusts of up to 90mph to Northern Scotland on December 7 as well as snow across the UK, and Storm Dylan brought a wet and windy end to 2017.

[UK Weather Forecast: Today's weather and the 5-day forecast]

But why did the Met Office begin naming storms? And what storm names can we expect this year? We take a look:

Why do storms now have names?

In 2015 the Met Office and its Irish counterpart Met Eireann launched a project to name severe winter storms, much in the same way that hurricanes are named. Giving each severe storm a name allows the approach of the storm to be communicated more uniformly.

[In pictures: When were Britain's worst winters?]

“Last year was another successful pilot of the storm naming project and it’s great to be now making it operational,” said Derrick Ryall, Head of Public Weather Services at the Met Office.  

“Naming storms has been proved to raise awareness of severe weather in the UK, crucially prompting people to take action to prevent harm to themselves or their property.”

Why do storms have names?

Previously UK storms were often given unofficial names by the press. The same storm could be given different names by different sources, so it was confusing.

“We noticed that various organisations during the last couple of winters, when we have had bad storms, started giving names to them. Think back to the St Jude’s day storm in 2013, and the 2011 hurricane in Scotland. But it led to confusion because certain organisations named the storms differently,” a Met Office spokeswoman told the Guardian in 2015.

Giving the storms a name – anthropomorphising them as already happens in North America – should also help raise awareness amongst the public of potential severe weather events, and will help people prepare for the worst.

If a storm hits the UK which has already developed over the Atlantic – and has already been named – then the original name will be used, and not one from the Met Office list.

Who chooses the names?

We do! The Met Office and Met Éireann asked members of the public to suggest names and compiled the list from those. The names run in alphabetical order and alternate between male and female. The gender of the first storm alternates each season and this season will be female.

Which storms qualify for names?

To be given a name, a storm must usually be a wind storm forecast to require amber or red warnings with the potential to cause either medium or high impact. An amber warning means ‘be prepared’ and red means ‘take action’.

November 2015's Storm Abigail saw yellow and amber warnings issued, while Storm Desmond prompted more than 120 flood warnings as well as a red warning for rain.

The Met Office also includes potential impacts from rain and/or snow when considering naming storms. 

Cumbrian village hit by flooding

What names will be used this winter?

The storm names chosen by the Met Office and Met Éireann for 2017/18 are as follows:

A - Aileen - September 12-13
B - Brian - October 21-22
C - Caroline - December 7-9
D - Dylan - December 30-31
E - Eleanor - January 2-3
F - Fionn - January 16
G - Georgina - January 23-24
H - Hector
I - Iona
J - James
K - Karen
L - Larry
M - Maeve
N – Niall
O - Octavia
P - Paul
R - Rebecca
S - Simon
T - Tali
V - Victor
W - Winifred

That's only 21. Why are some letters missing?

The US National Hurricane Center, which names - you guessed it - hurricanes, does not use names beginning with the letters Q, U, X, Y and Z. The Met Office and Met Eireann have decided to follow suit. As storm systems often develop over the North Atlantic, they want to be consistent with their American colleagues.

[Read more: How to storm-proof your home]

Why are some names avoided?

If a name is already associated with a previous devastating weather event - like Hurricanes Katrina or Sandy - then it won’t be re-used.

What happens if there are more than 21 storms in a year?

The Met Office would start again with another name beginning with ‘A’. However, according to Met Office spokeswoman Lindsay Mears, “it’s unlikely we would get through the whole alphabet in one season. To put it in context we had 14 storms in the very bad winter of 2013/14, so if the naming system had been in operation we wouldn’t have used the whole alphabet.”

In the case of tropical storms, if there are more than 21, the Greek alphabet is used to name the next storms. So, the 22nd storm would be Storm Alpha.

Hurricane Patricia

What other types of weather are named?

Tropical storms – hurricanes, cyclones and typhoons – are also given names.

When did meteorologists start naming weather systems?

British-Australian meteorologist Clement Lindley Wragge is credited with starting the convention of naming tropical storms in 1887. He first used the Greek alphabet but also names from history, Polynesian mythology and politics (particularly politicians he didn’t like). After his death, the practice stopped.

During World War II American meteorologists started giving tropical storms women’s names – often the names of their wives and girlfriends – to help clarify weather information for pilots. In 1953, the American National Weather Service adopted the practice. It was only in 1964 that Australia officially revived the practice of naming their cyclones. The first one was called Bessie. Northwest Pacific tropical cyclones were given names starting in 1945, with men’s names included from 1979.

In 2015, with more and more devastating storms hitting our shores, the UK decided to follow suit.

What has been the most devastating storm to hit the UK?

In living memory, the UK has been unfortunate enough to be hit by some destructive weather.

Going back to 1953, the North Sea flood was a devastating storm tide which affected the eastern coast of the UK. 326 people were killed, 30,000 evacuated and 1,600 km of coastline damaged.

Why do UK storms have names?

Who can forget the ‘Great Storm’ of 1987 when BBC weather presenter Michael Fish got it so badly wrong? Despite his alleged predictions to the contrary, hurricane-force winds hit the UK, with the South worst affected. 18 people died and there was an estimated £1 billion of damage.

[Read more: Extreme weather: When were the UK’s worst storms?]

The floods in 2000 affected a large swathe of England and Wales. The wettest autumn for more than 200 years wreaked more than £1 billion of havoc.

The winter of 2013 saw wind gusts of more than 100mph in parts, with plenty of damage from falling trees, whilst flooding saw thousands evacuated.