Storm Emma - as it happened: Thousands of trains and flights cancelled across UK as freezing weather and heavy snow set to continue

Good morning and welcome to The Independent's live updates as extreme winter weather continues to cause widespread disruption across the UK.

Hundreds of drivers and rail passengers were left stranded overnight as extreme weather continues to wreak havoc across the UK.

Two police forces declared “major incidents” as the Army was drafted in to help rescue those left trapped in their cars.

South Western Railway passengers were trapped in frosty carriages overnight after a broken-down train caused tailbacks on the rest of the tracks.

Here's our round-up of the key points as Britain faces another day of severe disruption:

Army called in to rescue drivers trapped in their cars by heavy snow

The fourth day of extreme cold across the UK has begun with even more travel disruption. 

Roads in South Wales, the south and south-west of England, and the Pennines have been closed, with hundreds of cars stranded overnight.

Most train operators have sharply reduced their services, with Arriva Trains Wales cancelling all services except the North Wales line.

Almost all flights from Scotland's biggest airports, Edinburgh and Glasgow, are cancelled this morning, while British Airways has cut almost 200 so far at Heathrow.

The Independent's Travel Correspondent Simon Calder has more: 

Many of Britain's roads, railways and runways are at a standstill as Storm Emma chaos continues

The National Grid has withdrawn a gas deficit warning a day after said supplies could run out as freezing temperatures across the UK caused increased demand.

In a short statement early this morning, the operator of the UK’s power network said it had withdrawn the warning with immediate effect and that more information, both on the initial warning and the withdrawal, would be issued in due course.

Yesterday the National Grid had said there had been gas supply losses due to the “extreme weather conditions”. It said that such a deficit warning was part of its “normal toolkit in extreme weather to make sure we can balance gas supply and demand”.

Here's our full story:

National Grid withdraws gas deficit warning issued for extreme weather conditions

Military deployed to Manchester to rescue drivers as weather shuts motorway

The military has been sent in to help stranded drivers on the M62.

Greater Manchester Police said the motorway has been closed between junction 20 (Rochdale) and junction 24 (Huddersfield) amid heavy snow and strong winds.

The force said it was aware of drivers who have been "stranded for some hours" following blizzards.

"We are aware of drivers in the surrounding area who have been stranded for some hours due to snow and wind," it said in a statement.

"The military have been deployed to support us and our partners in our efforts to clear the roads and get people to safety.

"We are filtering traffic off the M62 at junction 20 and diversions are in place although traffic is severely congested."

Volunteers have been taking supplies to drivers stuck on the motorway.

Traffic queueing to leave the M62 motorway 

Volunteers taking supplies to stranded drivers on the M62 at Milnrow 

Thousands of homes lose power

Thousands of homes are without electricity in north England, where temperatures remain below zero.

Power company Electricity North West said outages had affected parts of Stockport, Oldham, Preston, Blackburn, Bolton, Manchester, Carlisle and other parts of Cumbria. The problems are also affecting homes in Derbyshire, where 5,000 households are without power in Buxton alone.

The firm said some of their engineers have been forced to halt repairs because of the danger posed by high winds and heavy snow.

Theresa May has thanked the emergency services and healthcare staff for keeping public services running during the extreme cold weather. She issued the message on Twitter alongside a picture of a snowy Downing Street.

Transport Secretary Chris Grayling described the weather as "exceptional circumstances" for the UK and said that people stranded on roads and trains had had a "tough night".

He told Sky News: "In the case of the train on the south coast - we need to do everything we can to resolve that situation as quickly as possible.

"This is particularly unusual weather, it's something that happens very rarely in this country."

He added that there is a "huge" stockpile of salt for gritters out on the UK's roads.

Police and fire crews rescued "hundreds" of stranded drivers across Devon and Somerset last night.

Chief Inspector Adrian Leisk, who heads road policing across the two counties, sounded a note a frustration about the number of motorists who took to the "treacherous" roads being urged to avoid all non-essential travel.

A Met Office red warning for snow, signalling an increased risk to life, was in place in the region last night. A yellow warning for snow and ice is in place today.

A seven-year-old girl was killed in Looe, Cornwall, when a car crashed into a house in a "weather-related" collision yesterday afternoon.

All 279 schools in Cornwall are shut today as the county deals with snow, ice and flooding.

Devon and Cornwall Police have urged people to avoid all travel unless essential.

Trees have fallen in Gweek and Praze, with snow drifts and abandoned vehicles blocking roads, and emergency services are dealing with reports of flooding in the Lizard area.

Five properties have flooded in Porthallow, due to high tide, strong winds and run off from melting snow.

Mourners are being asked to check that funerals have not been re-arranged, though Penmount Crematorium is operational.

Almost the entire country is now covered by a Met Office yellow warning for snow and ice. Previously most of the UK had been under a a more severe amber warning.

While the downgrade may be a sign that an end of the arctic weather is in sight, forecasters are still warning of dangerous conditions in many parts of the UK and delays or cancellations on public transport throughout today.

"Patchy freezing rain will affect some southern parts of England and well as west Wales until early afternoon, leading to icy stretches which may be difficult to see," said the Met Office. 

"There is also an increasing chance that a further spell of more persistent snow may move north northwards across southern England, Wales and central England during the day, reaching northern England by evening, producing further accumulations. Further snow is also likely over parts of Northern Ireland.

"In addition, strong winds will lead to further drifting or blowing around of existing snow cover. Delays and cancellations to public transport are possible, as are delays to travel on roads; some stranding of vehicles and passengers could also occur.

"Some rural communities could become, or remain, cut off. Interruptions to power supplies and mobile phone coverage are also possible."