The recent bad weather is not caused by any one thing, Met Eireann says
Unusual persistent strong west-south-westerly air flows over the country as the predominant causes of the extreme weather this December, but it’s difficult to pin point it to one specific thing.
However, Met Eireann said that it is very difficult to determine the exact causes of the recent extreme weather.
Some studies suggest that the El Nino event in the Pacific is likely to increase the risk of strong jet streams, heavy rainfall and stormy conditions during winter, it said.
Climate change models suggest that with rising temperatures leading to an increase in the water carrying capacity of the atmosphere, with which Met Eireann has said we can expect an increase in the frequency and intensity of severe weather events.
However climate needs to be assessed over a number of decades before we can confidently identify genuine trends, it said, as opposed to natural variability.
Throughout December, unusually high frequency of southerly or south-westerly winds persisted, with warm and moist tropical air masses bringing very mild, wet and stormy weather over Ireland, Met Eireann said.
The widespread flooding in some parts of the country was exacerbated by already saturated ground following above normal rainfall in November.
The combined rainfall totals for November and December were the highest on record in some parts of the country, in particular at Shannon, Cork and Knock airports.
Met Eireann said that jet streams play a key role in determining the weather, which generally don’t follow a straight path and normally have peaks and troughs.
This December there was a pattern of continuous troughs and ridges across the North Atlantic and over Ireland giving us a mild predominantly south to south-westerly airflow, it said.
This resulted in a prolonged spell of very mild and very wet weather during which record temperatures and rainfall amounts occurred.