2017 hurricane forecasts suggest below average season due to El Niño

by Artemis on April 19, 2017

A number of forecasts have been released for the 2017 Atlantic Tropical Storm & Hurricane Season and so far all are calling for activity levels just below the long-term average, with the expectation that we will see a weak El Niño by the typical peak of the season suggesting a slower year.

2017 hurricane season forecastIt’s a very similar situation to this time last year, when the early hurricane season forecasts were largely suggesting a more active year due to the state of the El Niño Southern Oscillation (ENSO), and whether it would be neutral or a La Niña, expected to have a strong influence on activity.

In 2017 we find similar factors at play, with the state of the ENSO forecast to define just how active a hurricane season the insurance and reinsurance industry sees, but this year meteorologists are largely anticipating a shift to El Niño conditions by the summer and just before the traditional peak of the hurricane season, although uncertainy remains (of course).

With a number of the main forecasters now having their predictions for the season published, we’ve launched an updated page for our readers to track the 2017 Atlantic hurricane season throughout the year.

From the forecast storm numbers below it’s clear that while the predictions are for a below average season, it is only slightly so and in terms of hurricanes and major hurricanes it is of course the location and track that really matters to the insurance, reinsurance, catastrophe bond and ILS industry.

2017 Atlantic hurricane season forecasts

As we’re all aware, it only takes one of the forecast major hurricanes to track towards a major city on the U.S. Gulf or East Coast and, no matter how average the seasonal activity is, it will be above the recent average for insurance and reinsurance interests.

Last year the insurance and reinsurance industry is estimated to have paid around $4.5 billion of claims due to tropical storms and hurricanes, with Matthew the major driver. Prior to that with no landfalling storms for a number of years, the re/insurance sector has got off lightly, while catastrophe bond and ILS investors could be forgiven for forgetting that U.S. hurricane risks remain the dominant peril in the marketplace.

In 2017 it looks like there will be quite a lot of uncertainty surrounding hurricane activity, both in the Atlantic and Gulf basins. With a developing El Niño on the cards it becomes very difficult to predict how conditions such as storm surge, prevailing upper-level winds, sea-surface temperatures both in deeper water and nearer the coast, will impact the development, paths and intensity of any tropical storm that forms.

One of our go-to forecasters over nearly two decades has been Colorado State University and Phil Klotzbach who leads the team there today had the following to say about the 2017 hurricane season.

“The current neutral ENSO is likely to transition to either weak or moderate El Niño conditions by the peak of the Atlantic hurricane season. The tropical Atlantic has anomalously cooled over the past month and the far North Atlantic is relatively cold, potentially indicative of a negative phase of the Atlantic Multi-Decadal Oscillation,” he explained.

Encouragingly for the insurance, reinsurance and ILS investor community, Klotzbach and his forecasting team believe there is a lower probability of major hurricane landfalls in 2017.

“We anticipate a below-average probability for major hurricanes making landfall along the United States coastline and in the Caribbean,” he continued.

The Colorado State forecast suggests a 42% chance that at least one major hurricane makes landfall somewhere on the U.S. coast, lower than the average for the last century of 52%. For Florida and the East Coast that sits at 24%, below the average 51%. While for the Gulf Coast it sits at 24%, below the 30% average.

This and the other forecasts at this point in the year are, of course, long-range and so should be treated as such and notice should be taken of the updates that come out as the 2017 U.S. hurricane season approaches.

Tropical Storm Risk, another of the long-time go-to forecast teams, offers a similar view on the 2017 season, having recently reduced its forecast due to the expectation of El Nino occurring later this year.

TSR explains; “The reason why the TSR forecast for North Atlantic hurricane activity in 2017 has fallen by 30% since the TSR extended range outlook issued in December 2016 is the anticipated development of a moderate El Niño by the summer/autumn of 2017. This El Niño development was not foreseen in December 2016.”

Both TSR and Colorado State now provide the same forecast for the 2017 season, of 11 named tropical storms, 4 hurricanes and 2 major hurricanes of category 3 strength of greater.

TSR does not provide landfall probabilities in the same way as Colorado State, but they do suggest that 2 named storms will make landfall during the season in 2017, but no hurricanes, which would be a welcome outcome for insurance, reinsurance and ILS interests.

Again, we must note the uncertainty here though, as this is a long-range forecast and the development or otherwise of ENSO related conditions could have considerable bearing on landfalls, as well as other factors from the jet stream to dust storms coming off the African land mass.

Meteorologists at Accuweather are also focused on ENSO conditions as a factor driving 2017 hurricane activity.

AccuWeather Meteorologist Dan Kottlowski said; “The big factor is going to be the fact that we now believe El Niño will come on board some time during the summer and will continue all the way through the rest of the hurricane season. That’s the number one reason we’re going with just below normal”

Accuweather too plumped for a below average forecast, with El Nino the main factor behind this decision.

The Weather Company also went with a below average forecast due to the potential ENSO conditions during the peak season, but Dr. Todd Crawford, chief meteorologist there explained that this could prove to be wrong if ENSO conditions change.

“If El Niño fails to launch, we may be too low with our numbers,” Crawford said, explaining that as well as ENSO the sea-surface temperature development through the season would be a key driver of activity potential.

Finally we look to Weatherbell Analytics LLC and Joe Bastardi, another forecaster we’ve tracked over the years.

Weatherbell too is forecasting below average activity across the 2017 Atlantic hurricane season, but Bastardi cautions that while the development of an El Niño would likely put a quicker end to the season, “Some big names have shown up in El Niño years.”

Weatherbell also provides a view on where in the Atlantic and Gulf activity may be above or below average and opts for lower activity in the main tropical development zone of the Atlantic Ocean, but potentially above average activity in the Western Gulf of Mexico and off the U.S. East Coast (as seen below).

2017 hurricane activity forecast

Weatherbell say overall activity is forecast to be below average, but closer in to the U.S. coastline it gets more difficult to predict and warmer waters in the Gulf and off the East Coast will have the potential to feed storms.

Activity levels in the 2017 Atlantic hurricane season will depend on how early an El Niño emerges and how strong it is, as if it only occurs later on in the season the peak could still see conditions that would be conducive to greater activity than these forecasts currently predict.

There are a number of meteorologists who are calling for El Niño to be a late developer in 2017, adding uncertainty to any longer range hurricane season forecast this year.

Hence the forecast updates just in advance of the season, and during the hurricane season itself, will be important this year, as ENSO measurements should allow greater confidence in the timing of a developing El Niño as the year progresses, so don’t be surprised to see the forecast numbers change.

We’ll update you as the 2017 Atlantic hurricane season develops and our dedicated page on the 2017 hurricane season will be updated as new forecasts emerge and as storms form throughout the year.

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