ieExplains: Why are we seeing so many storms this season?

The answer, according to Met Éireann, is down to the position of the North Atlantic jet stream.

This determines how many low-pressure systems travel close to, or directly over, Ireland each season. The strength of this stream and how each low-pressure system interacts with it will determine whether it will intensify enough to create an Atlantic storm.

The position of the jet stream over the North Atlantic can be affected by a variety of complex factors. Therefore, it is extremely difficult to accurately predict a storm more than one week before it arrives.

Due to the size and location of Ireland, sitting on the edge of north-western Europe, there are moments when the country is not impacted by Atlantic storms. Often, the jet stream directs Atlantic storms further north or further south with little or no impact here. 

However, recently there has been a surge in Atlantic storms directed by the jet stream towards Ireland, causing high-impact and severe damage across the country.

Why is this the case?

The current position of the jet stream allows more Atlantic storms to be directed towards Ireland and the UK, increasing the risk of storms.

The jet stream has been very active since August 2023, cooling off over the first half of January, before intensifying over the last couple of weeks. This has led to a resurgence in storm warnings.

Over the last few weeks, the jet stream, influenced by a “large temperature contrast” over the eastern part of the US, was slightly further north again compared to earlier in the season.

This directed the low-pressure centres to the north of Ireland, bringing Storm Isha and Jocelyn to our shores, Met Éireann explained.

"The strongest winds of mid-latitude storms are usually on the southern side of the low pressure system, and as both Storm Isha and Storm Jocelyn centres moved to the north of Ireland, the strongest winds associated with these storms hit Ireland and the UK," Met Éireann said.  

"Other named storms, such as Storm Ciarán, missed Ireland to the south, with the strongest winds hitting France and/or Spain instead.

Met Éireann climatologist Paul Moore said: “The position and strength of the North Atlantic jet stream determines the number and intensity of Atlantic storms that affect Ireland in any given storm season. The North Atlantic jet stream is driven by the temperature differences between the north and south and tends to be strongest in winter when the temperature difference is at its highest.

"The variation in the North Atlantic jet stream from year to year and week to week is further influenced by complex interactions between many different components and drivers of the global weather system such as the North Atlantic seas surface temperatures, the El Niño-Southern Oscillation, the Madden-Julian Oscillation and the Stratospheric Polar Vortex in winter.”