An amber warning for snow and ice, with the risk of freezing rain, covers most of Wales and central England until midday on Sunday.

Freezing rain, which makes up what are commonly known as ice storms in North America, is a rarity in the UK because the conditions for it are quite specific, according to the Met Office.

But what is it and how is it different to snow?

Freezing rain is rainfall that has become “supercooled” as it falls from the sky.

Up to 30cm of snow expected in parts of UK – follow live

It starts when snow, ice, sleet or hail high up in the atmosphere melts into rain when it falls through the layers of warmer air below.

If the rain then passes through a sub-zero layer of air just above the ground, it can remain liquid and instead become “supercooled”. This is the key to freezing rain.

Supercooled water will freeze on impact – forming a clear layer of ice on cold surfaces such as trees, roads and power lines.

Why is it dangerous?

It’s once it hits the surface and turns to ice that it can pose a real threat.

The ice is very clear, often referred to as black ice, because it is so difficult to see, making it treacherous for pedestrians and drivers.

Sky News meteorologist Kirsty McCabe explains: “The supercooled rain hits the ground and freezes instantly on impact, and that creates a thin layer of ice, also known as glaze, and it’s clear, so you can’t see the ice, which makes it really treacherous.”

If it hits power lines or tree branches, depending on how much rain there has been, the weight of the ice can cause them to break off because they can’t support the weight.

It can also make it difficult to open your car door if there is enough of it.

Get the five-day forecast where you are

Where is it expected to fall?

From 6pm on Saturday to midday on Sunday an amber warning for snow and ice, with the risk of freezing rain, covers most of Wales and central England, including the Midlands and Liverpool and Manchester in the North West.

But McCabe says it’s Wales where people should be particularly wary of freezing rain.

What precautions should people take?

The best thing people can do is take extra care when travelling. As it is so hard to see, it’s difficult to judge just how icy road surfaces are.

The RAC says freezing rain is arguably the most treacherous of all conditions for motorists.

They urge people not to drive unless necessary, but say those who do need to should check they have plenty of fuel and oil and check their tyre treads.

They also encourage drivers to make sure their lights are working and check they have screenwash.

The King is deeply saddened by the death of a British man who was killed in the attack in New Orleans on New Year’s Day – amid reports he was the stepson of an ex-royal nanny.

Edward Pettifer, from Chelsea, west London, was fatally injured in the tragedy, the Metropolitan Police confirmed.

Sky News understands the King was made aware of Mr Pettifer’s death through official channels, was deeply saddened, and has been in touch with the family to share personal condolences.

The 31-year-old’s family said they were “devastated” by his death.

“He was a wonderful son, brother, grandson, nephew and a friend to so many,” the family said in a statement.

“We will all miss him terribly. Our thoughts are with the other families who have lost their family members due to this terrible attack. We request that we can grieve the loss of Ed as a family in private.”

New Orleans’ coroner said the preliminary cause of death for Mr Pettifer was blunt force injuries.

Fourteen people were killed and dozens injured when 42-year-old army veteran Shamsud-Din Jabbar’s rented truck rammed into people in New Orleans’ famous Bourbon Street in the early hours of New Year’s Day.

Jabbar was killed in a shootout with police.

The Federal Bureau of Investigation (FBI) said the attack was “premeditated” and an “evil” act of terrorism, and added Jabbar was “100% inspired by ISIS”, also known as Islamic State.

The preliminary cause of death for all the victims was blunt force injuries, according to the New Orleans coroner.

The coroner has identified most of those killed in the attack, with efforts continuing to identify the final female victim.

• Edward Pettifer, 31, from Chelsea, west London
• Andrew Dauphin, 26, from Montgomery, Alabama
• Kareem Badawi, 23, from Baton Rouge, Louisiana
• Brandon Taylor, 43, from Harvey, Louisiana
• Hubert Gauthreaux, 21, from Gretna, Louisiana
• Matthew Tenedorio, 25, from Picayune, Mississippi
• Ni’Kyra Dedeaux, 18, from Gulfport, Mississippi
• Nicole Perez, 27, from Metairie, Louisiana
• Reggie Hunter, 37, from Prairieville, Louisiana
• Martin Bech, 27, from New York City, New York
• Terrence Kennedy, 63, from New Orleans, Louisiana
• Elliot Wilkinson, 40, from Slidell, Louisiana
• William DiMaio, 25, from Holmdel, New Jersey

Read more:
What we know about suspect
British man, aspiring nurse and Princeton University football player among victims
Did New Orleans authorities fail the victims of the New Year terror attack?

An Islamic State (IS) flag, weapons, and what appeared to be an improvised explosive device (IED) were found in the vehicle used in the attack, the FBI said.

The suspect posted five videos on social media before the rampage in support of IS, the agency added.

In his first clip, Jabbar said he was planning to harm his own family and friends, but was concerned headlines would not focus on the “war between the believers and disbelievers”, said Christopher Raia, deputy assistant director of the FBI’s counter-terrorism division.

Jabbar also joined IS “before this summer”, and provided a will, the FBI chief said.

In an interview with a Texas-based TV station, owned by Sky News’ partner network NBC News, Jabbar’s younger half-brother said he was thinking about all those impacted by the attack.

Abdur-Rahim Jabbar said: “This is a tragedy. We’re all grieving about this.”

The suspect was a Muslim, with his sibling adding: “This wasn’t the man I knew. This wasn’t the father, the son that I knew.

“And that also, this isn’t any representation of Islam or Muslims or the Muslim community.”

Stargazers spied an unusual sight on Friday night, as Venus appeared beside a crescent moon.

The planet could be seen with the naked eye in locations lucky enough to have clear skies and incredible pictures show it seemingly shining.

Venus is often called the Morning or Evening Star, as it can easily be mistaken for a bright star.

January looks set to be a good month for stargazers and astronomers, as numerous celestial phenomena will be visible across the coming weeks.

The Quadrantid meteor shower is at its peak this weekend and visible until 12 January.

On 16 January, there’s a strong chance you’ll be able to see Mars as the red planet will be in “opposition”, meaning Earth will be directly between it and the sun.

Just under a week later, on 21 January, you could see five planets – Saturn, Venus, Uranus, Jupiter and Mars – in the night sky after 9pm, according to the Royal Observatory Greenwich.

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Four of the planets should be visible to the naked eye, but seeing Uranus will require a telescope or very dark skies.

Anyone hoping to spot celestial phenomena is advised to find a stargazing spot away from light pollution and to allow at least 15 minutes for your eyes to adjust to the darkness.