“The position of the Polar jet stream is of paramount importance to the type of weather we experience. If it sits well to the north of Ireland, one can expect mild and breezy weather, and occasional settled spells. The Atlantic storms frequently pass by to the north, so they only clip north-western areas,” he explained in its latest research on Ireland’s winter weather.
However, this winter the Polar jet stream extended across the Atlantic right over Ireland marking the tracks of successive storms, giving us wet and stormy weather, he added.
“A combination of strong winds, tidal surges and low pressure conspired to cause widespread damage and flooding during the latter half of December 2013 and into the middle of February 2014. During January and February the tracks of the storm moved southwards. Peak wave periods were unusually long and record wave heights culminated in severe flooding and widespread damage chiefly along the southern, western and north western coastal areas. The effects of the storms were exacerbated by very high tides.”
Storm force winds were recorded on 12 different days, on the 5th/14th/18th/24th/26th/27th of December 2013 and 3rd/25th/26th of January and 1st/8th/12th of February 2014.
“This series of storms led to an increase in rainfall amounts of between one and a half and two times above normal and to saturated or waterlogged ground throughout the country,” the weather expert explained.
“The most severe windstorm occurred on the 12 February 2014 and was associated with an active depression off the south coast that tracked steadily north-eastwards over the country.” Meanwhile, Kinsale Energy Gas Platform recorded a maximum wave height of 25m on the same day, its highest on record.
So was the recent stormy weather caused by climate change?
“The answer is we can’t say for sure,” according to Met Eireann’s Murphy.
“The distinguishing feature of the weather this winter was the seemingly unending series of vigorous Atlantic storms that crossed the country. Nevertheless only one individual storm, on the 12 February 2014, could be considered exceptional but not without parallel. We have had more violent storms in the past such as Hurricane Debbie in 1961, where the maximum gusts were between 70 and 85 knots generally with a maximum of 93kt reported in the northwest. The more recent storms of 26 December 1998 and 24 December 1997 were also of greater intensity.
He continued: “In February 1990, an unusually long series of vigorous storms crossed the country producing record winds and rainfall amounts. Some 175 years ago, on the 6/7th January 1839, a hurricane known as the ‘Night of the Big Wind’, raged across Ireland. The following sentiments expressed in the Evening Post the next morning still remain valid today: Comparing it with all similar visitations in these latitudes, of which there exists any record, we would say that, for the violence of the hurricane and the deplorable effects which followed, as well as for its extensive sweep, embracing as it did the whole island in its destructive career, it remains not only without a parallel, but leaves far and away in the distance all that ever occurred in Ireland.”
According to murphy, some recent climate change studies suggest an increase in the intensity of Atlantic storms that take a southerly track and that extreme rainfall events are becoming more frequent, consistent with the physics of a warming world.
“Climate needs to be assessed over a number of years before we can confidently identify genuine trends, as opposed to changes associated with natural variability,” he added.