Storm Ciarán is likely to lash Britain with more rainfall than normal because of a “rare” low pressure, a climate expert has said.
The Met Office has issued amber weather warnings for the south west and the south coast ahead of Storm Ciarán’s making landfall on Thursday (November 2).
It came amid yellow warnings for wind and rain which are already in place across parts of England, Scotland and Wales between Wednesday and Friday.
Reading University climate scientist, Ed Hawkins, warned the storm may see more rain, with possibly the lowest sea level pressure in 200 years.
Mr Hawkins tweeted: “On Thursday #StormCiaran is forecast to cross southern England. The track is still a bit uncertain but will bring very strong winds to southern areas.
“At around 953mb this will likely be the lowest or second-lowest sea level pressure observed in this region in the last 200 years.”
He followed up on his initial tweet, adding it would be “a very rare occurrence” as there are only two other similar events for pressure in observational records, February 25, 1989, and Christmas Day, 1821.
Mr Hawkins said: “This storm will also likely drop more rain than it would have done had it occurred a century ago as the atmosphere is warmer [and] more humid now.”
Weather expert Phil Morris explained sea level pressure is the pressure of the air at zero feet, adding: “On Thursday the centre of the low will have a sea level pressure of 955 millibars over Norfolk travelling north east from Cornwall during the morning.
“This could be a record low pressure area for November over England. At the moment the 70-90mph winds will be over Cornwall and the Channel Islands in the morning, transferring to the south coast and Kent as the day goes along.
“Any movement of the low north could bring the stronger winds further north too. Most weather models are agreeing a track from Cornwall to East Anglia with the exceptional winds on its southern flank.”
He added all Storm Ciarán’s bands of rain will circulate around the centre of the low with winds also revolving around this point – the centre and pivot point of the storm.
Mr Morrish continued: “In this low pressure area the strongest winds are on the southern flank and not right in the centre. The Channel Islands will be worst affected with gusts over 90mph, as will northwest France.”
Met Office Chief Meteorologist Dan Suri, said ahead of Storm Ciarán, a squally cold front will move eastwards across southern and southeast England on Wednesday (November 1), bringing bursts of heavy rain and coastal gusts of 60-70mph, mainly from Dorset eastwards.
He added: “Wind and rain warnings associated with Storm Ciarán are in force from Wednesday night onwards into Friday, with further updates possible on Wednesday.
“These include amber warning for winds for southwestern parts of England and Wales Thursday early hours and morning and the far south and southeast of England Thursday daytime and early evening.
“Storm Ciarán is expected to bring very strong along southern coastal areas of England in particular where gusts of 70 to 80mph are possible, gusts perhaps exceeding 85 mph in the most exposed locations. Further inland, gusts could reach up to 50 or 60mph.”
Mr Suri said that as well as strong winds, the deep low pressure system will bring heavy rain to many parts of the UK.
He added much of southern England and south Wales, as well as parts of north Wales, northeast England, southeast Scotland and perhaps the east of Northern Ireland look to see the wettest conditions between Wednesday evening and Friday morning.
Between 20-25 mm of rain may fall quite widely, with 40-60 mm possible over higher ground, according to the Met Office meteorologist.
The weather expert concluded: “Some parts of south Wales and southwest England may see 80 mm of rain. This rain will fall on already saturated ground, bringing the risk of flooding.”
On the outlook for the weekend, Met Office Deputy Chief Meteorologist, Steven Keates, said once Storm Ciarán has passed, the weather continues to look unsettled for many with more showers and rain at times.
