AG百家乐在线官网

Explainer

UK weather: Storm Ciaran's dangers - chance of 'sting jet' phenomenon like 1987 and record-breaking lows

Most storms can be tracked as they make their way across the Atlantic or from the continent. But Ciaran hasn't finished developing - and until it does, it's very hard to pinpoint the areas that will be worst affected and also the strength of the winds.

Please use Chrome browser for a more accessible video player

Welcome live coverage as Storm Ciaran makes landfall in the UK
Why you can trust Sky News

Even with the strongest rose-tinted glasses, the next few days are going to bring some fairly rough conditions.聽

For most, this may spark a second thought about travel plans or fireworks celebrations.

With three areas of low pressure crossing the country, most parts will see spells of rain and gusty winds; a typically autumnal weather pattern.

But Storm Ciaran provides a very different headache.

Follow live: Updates as storm sweeps in towards UK

Most storms can be tracked as they make their way across the Atlantic or from the continent. But Ciaran hasn't finished developing - and until it does, it's very hard to pinpoint the areas that will be worst affected and also the strength of the winds.

This is because Ciaran is far more likely to represent a danger from wind, not rainfall.

More on Uk Weather

But with ground already saturated in many parts of the country, any further rain is likely to cause issues.

Cars driving through flood water near Whitley Bay, on the North East coast of England. Much of the country is bracing itself for a fresh bout of wind and rain with Storm Ciaran bringing amber alerts on Thursday morning. Picture date: Wednesday November 1, 2023.
Image: Flooded roads in the north east of England

Record-breaking low pressure caused by temperatures in North America

The situation is this: there's a very strong jet stream across the Atlantic.

It has been given superpowers thanks to a temperature discrepancy between Canada and the United States.

Its hurtling trajectory across the ocean has swept up Ciaran, which will gather energy before exiting the jet and heading towards the UK and Ireland.

What's a 'weather bomb'?

Explosive cyclogenesis occurs when the central low pressure of a storm drops at least 24 millibars within 24 hours, according to the National Oceanic and Atmospheric Administration (NOAA) in the US.

A millibar is a unit of pressure that measures the weight of the atmosphere 鈥� for example sea level pressure is around 1,010 millibars.

It's sometimes called 'bombgenesis' or a 'weather bomb'.

The phenomenon occurs when warm and cold air masses collide 鈥� and happen most often in colder months.

Within this process, Ciaran will see its central pressure drop rapidly - this is called explosive cyclogenesis - or a weather bomb. In fact, Ciaran may break records for its low pressure centre.

The practical impact is likely to be the development of some extremely strong winds on its southern flank - so the strongest winds follow the storm rather than accompanying it.

And the areas affected are hard to pinpoint given that Ciaran has yet to reach its full potential.

But it seems likely that southern England, south Wales and the South East are most likely to see wind gusts in excess of 80mph with amber warnings in force there.

The Channel Islands and France have both issued red warnings, which mean a danger to life.

Met Officer weather warnings for wind and rain on Wednesday
Image: Met Office weather warnings for wind and rain on Wednesday...
Met Office weather warnings for wind and rain on Thursday
Image: ...and Thursday...
A Met Office yellow weather warning for rain on Friday
Image: ...and Friday

Sting jet could bring 100mph winds to very small area

There is also the possibility of a sting jet developing - a small core of yet stronger winds.

These are associated with areas of rapidly deepening areas of low pressure and will be best remembered from the storm of 1987.

In essence, this is a small area of very intense winds, occasionally exceeding 100mph.

Mostly they affect an area of only 30 miles across and are of a fairly short duration; three to four hours.

Channel Islands and France could bear brunt instead

While all extreme weather events represent danger, their location is also hugely important.

The south is a very populated area with a comprehensive travel structure - ferries, buses, trains and airports; an area far more vulnerable than the Scottish Highlands say, and a population simply not prepared for the potential ferocity of such wind strengths as they happen so rarely.

Ciaran's impacts are also likely to be very localised, with one area seeing destructive winds, while not too far away, there'll be no problems.

Indeed, if Ciaran takes a more southerly track, it'll be the Channel Islands and France that bear the brunt of the strong winds and, as a country, we'll be largely unaffected.

Be the first to get Breaking News

Install the Sky News app for free

Read more:
Analysis: Why Storm Ciaran will be so bad
Wet weather brings heavy flooding

As Ciaran makes landfall the storm will weaken and will continue to weaken as it moves northward.

So for much of the country, the next few days bring the kind of wet and windy weather you'd expect at this time of year, albeit with the issue of further rainfall adding to recent flood issues.

And, of course, strong winds threatening a good night out at the firework display.