El Nino predictions: what a weakening El Nino might mean

El Nino has been in a weak state since September 2018, with sea surface temperature values fluctuating between 0.5 and 1 Celsius above average.

El Nino is currently active in the Pacific, but it’s days are numbered.

It’s undergone minor weakening in the past month. The image below shows that weakening. The top picture is from the 13th of May 2019 and the bottom from the 13th of June 2019. Credit: NOAA.

Why is El Nino significant? The closer you are to the central Pacific, the more impact El Nino will have on your weather patterns, with some exceptions. Much of the US and Canada, isn’t far from the Pacific. El Nino influences our weather by altering trade winds above the Pacific, with are connected to the jet stream and weather patterns that affect North America by a network of atmospheric cells.

El Nino can increase precipitation rates in the southern half of the United States, this is a well known fact, however it’s questionable whether affects stretch farther afield. It could be argued that the floods to the Mississippi basin have been exacerbated by El Nino, but there wouldn’t be enough scientific grounds for this claim.

El Nino has a more apparent impact on hurricane season. Generally, when compared to the average year, El Nino sees a higher than average instance of tropical storm activity in the Pacific, and in contrast a lower than average instance of tropical storms in the Atlantic.

In an El Nino year “wind shear” is increased in the tropical Atlantic region – which helps to hamper growth of associated clouds of a hurricane. This is significant. As we head into 2019’s hurricane season, El Nino is likely to have weakened further, however is still likely to be designated “El Nino over” until mid Autumn.

The image below shows the slow downwards trend of El Nino into the end of 2019. – Credit: NOAA.

An average, to slightly stronger than average Atlantic hurricane season is well within realms of possibility. El Nino is significant, but MUCH warmer than average waters currently span much of the tropical Atlantic. 2018 wasn’t as warm at this point in the year (June), 2019 comes out 1 to 2 degrees higher in places where it matters. You can see for yourself (Credit: NOAA/NESDIS):

It’s way to early to say what El Nino might mean for Winter 2019/20. Winter forecasts use many atmospheric factors, “drivers”, combined with Pacific sea surface temperatures, to generate a winter forecast. Even then, it’s not 100%, as are hurricane season predictions, which is why you should take all this with a pinch of salt. The weather could do anything within possibilities and you should always be prepared.