27 May 2013

Active Atlantic hurricane season predicted for 2013

In just a few days’ time, the Atlantic hurricane season begins. Running from 1 June until 30 November each year, it is the time when conditions are most favourable for tropical storm activity in the Atlantic Ocean basin.

NOAA’s Climate Prediction Center produces an Atlantic hurricane season outlook each year. It details how active it expects the forthcoming season to be, as well as giving an indication of how many major storms of category three or above are possible.

Given that last year saw a greater number of named storms than normal, there will no doubt be plenty of interest as to what this year may bring – especially for those living in the Gulf of Mexico and along the east coast of the US.

Last year, Hurricane Sandy was the deadliest and most destructive storm of the season, killing around 280 people in an area stretching from the Caribbean, through the US and into Canada.

Sandy was also the second-costliest hurricane in US history, with an estimated $50bn worth of damage, with only Hurricane Katrina in 2005 proving more costly.

NOAA predictions for this year

This year, NOAA predicts that there is a 70 per cent chance of 13 to 20 named storms (winds of 39mph or above), with 7 to 11 becoming hurricanes (winds of 74mph or above).

Of these storms, it expects three to six to become major hurricanes at category three or above, with winds of 111mph or higher.

These predictions are well above the seasonal average of 12 named storms, six hurricanes and three major hurricanes.

Why is it likely to be a more active season?

According to NOAA, there are three climate factors that strongly control the Atlantic hurricane season that are expected to come together and make this year active.

The first is a continuation of the atmospheric climate pattern that includes a strong west African Monsoon. Clusters of thunderstorms that leave the equatorial west African coast are the seeds of what can go on to become storms.

Also, at the moment, water temperatures in the tropical Atlantic Ocean and Caribbean Sea are warmer than average. Hurricanes are fuelled by warm ocean waters, so any additional heat encourages their development.

Finally, El Nino, an anomaly in ocean temperatures off the west coast of South America, is not expected to develop. El Nino tends to suppress hurricane formation, so its absence favours storms developing more readily.

How many storms will make landfall?

This is one factor that is not known. While there are predictions of the number of storms that are likely to form, knowing the paths that they will take is simply impossible so far ahead.

Nevertheless, given last year’s active season, people in the areas at risk from being affected will be keeping a close eye on the National Hurricane Center’s forecasts.

In just a few days’ time, the Atlantic hurricane season begins, with NOAA’s Climate Prediction Center predicting an active season and an above-average number of storms.

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