How ‘La Niña’ will impact the weather - a colder, dryer winter is on the charts

Climatologist Cathal Nolan, founder of the online weather page, Ireland’s Weather Channel, this week said that given the moderate La Niña system occurring right now, it’s possible we could be in for a colder and dryer winter, much like that of 2010.

“Typically there’s two variations of the system – you either get El Niño, which means you get a lot more warmer water flowing off the coast of South America on the Pacific side, or you have La Niña, which is the opposite, and you get a lot of cold water in that particular region,” Cathal told the Westmeath Examiner last week.

“It essentially changes global weather patterns, more so across parts of the Pacific, parts of North America, but it can also have smaller but noticeable impact across parts of Europe as well.

“This particular time it’s a La Niña event and it’s expected to be of moderate strength.

“Typically when we see moderate to strong La Niña events, we experience more settled conditions across north western Europe during the winter months. For us, that means colder than normal conditions.”

The weather models reinforce this hypothesis, Cathal said.

“If you look at the more long-term weather models, they’re hinting towards a transition to more cooler conditions also, certainly through parts of November and December, and both months look to be colder than average.

“We look back at years that had similar conditions and try to extrapolate from them what we could expect to see weather-wise. It is worth mentioning, however, that you’re really only talking about the probability of it being warmer or cooler, dryer or wetter than average,” he added.

“La Niña years usually tend towards cold early winter months – November, December, January, as was the case of 2010 when we had an exceptionally cold winter,” he said.

“That was the last time the lakes were frozen enough in Westmeath for people to be able to actually walk on them. And that year was an example of a moderate to strong La Niña event which had the impact of producing much colder but also dryer than average conditions.

“So if you were to take the analysis that we’d have a similar pressure pattern this time around, it would certainly lead to colder than average temperatures and it would probably be dryer than average conditions.

“Typically when we have these types of blocking patterns in place – as is indicated for parts of December, it tends to bring in some wintry showers from the Irish Sea, and can give some snowfall, as was the case in 2010.”