Storm Ophelia: Facts and figures of the strongest east Atlantic hurricane in 150 years
The highest individual wave during the storm was 17.81 metres
Storm Ophelia evolved from the strongest eastern Atlantic hurricane in a century and half of records, but did not break the wave height record set by Storm Darwin off the south coast almost three years ago.
The tropical revolving storm which hit the Irish south coast early on Monday and swept across the island in a day caused one of five weather buoys to break its moorings off the Irish coast.
A separate individual wave height of 17.81 metres was recorded by the M5 weather buoy data recorder off the south-east coast at 4pm on Monday, and the buoy also recorded a significant wave height of 12.97 metres.
A significant wave height is derived from the average of the highest one third of waves measures from trough to crest in a given period.
The M5 weather buoy subsequently broke away from its mooring and the Marine Institute says it was recovered on Tuesday by the MV Puffin of Fastnet Shipping in Waterford and brought ashore that night.
As Ophelia moved northwards, the M2 buoy to the east of Dublin also experienced a record significant wave height of 6.64 metres measured at 6pm on Monday October 16th, the institute said.
Earlier in the day, at midday, the M3 buoy, off the south west coast measured an individual wave height of 13.59 metres, although this was not a record wave for this buoy, it says.
University College Cork climatologist Dr Kieran Hickey said the data so far did not indicate Ophelia broke land wind speed records, or wave records, but may break records for insurance claims - currently estimated at up to €800 million.
The Kinsale gas platform was hit by a 25-metre high wave in early 2014, the biggest instrumental record of a wave in Irish waters, Dr Hickey says.
Three people died in the Republic in tree-fall-related events as a result of Ophelia, whereas four people – possibly six – died in weather-related incidents during the sub-zero temperatures of December 2010.
Advances in meteorological tracking which informed the Met Éireann red alert, combined with the State national emergency co-ordination centre response to same, have been credited with ensuring that fatalities were not higher.
The last tropical revolving storm of its type, Storm Debbie in 1961, claimed 18 lives on the island – 12 in the Republic and six in the North. Storm Charley claimed 11 lives when it hit Ireland and Britain in 1986.
Dr Hickey, who is head of UCC’s department of geography, said Ophelia had one factor in common with the “Big Wind” of 1839, which caused hundreds of deaths, as in both cases the sweep affected the entire island to varying degrees.
“However, in 1839, there was far less information, a larger population, dwellings of many were more fragile, and recovery from injuries would have been far more challenging,”he said.
“There were fewer trees in 1839 and it was also during a winter month,” he said.
Dr Hickey said the top gust of 191 km/h recorded during Ophelia at Fastnet lighthouse off the south-west coast was taken by instruments at 200 feet or almost 70 metres.
The standard measurement for same is at 10 metres, and was set by Storm Debbie at Malin Head, Co Donegal, in 1961, when a speed of 181 km/h was recorded. It may be that the Storm Debbie wind record still stands.
Ophelia had sustained winds (10-minute mean) of 111km/h at Roches Point, off Cork, and gusts of up to 156km/h on land.
“We can say that Ophelia was the strongest eastern Atlantic hurricane on records – dating back to the mid 1800s – as a category 3 hurricane,” Dr Hickey said.
The tropical revolving storm occurred during the seventh most intense Atlantic hurricane season since 1850, with 10 hurricanes in 10 weeks so far.
“This is the only time 10 hurricanes have been recorded in a single season in the satellite era,” he said.
“The frequency could be comparable to 1878, 1886 and 1893 when there could have been a few more which were not recorded.”
Before Ophelia struck, recent hurricanes had already recorded 357 deaths and caused an estimated $186.8 billion in damages internationally. Hurricanes Harvey and José were both category 4, while Irma and Maria were both category 5 in the 1-5 hurricane scale.
There have been 45 deaths from such extreme winds in western Europe since 1961, according to Dr Hickey.