2nd June 2019
The 2019 North Atlantic hurricane season officially got underway yesterday and runs for six months through to November 30. Ahead of the start of the season, several forecasting groups and agencies have issued seasonal outlooks that provide a guide to the expected level of activity this year.
Most companies anticipate near-average activity in the Atlantic hurricane region, which comprises the North Atlantic Ocean, the Caribbean Sea, and the Gulf of Mexico. The U.S. National Oceanic and Atmospheric Administration (NOAA) is forecasting 9 to 15 named storms, 4 to 8 hurricanes, and 2 to 4 major hurricanes; these ranges are close to historical annual averages of 12 named storms, 6 hurricanes, and 3 major hurricanes. Outlooks from other forecast groups and meteorological agencies are broadly in line with the guidance issued by NOAA.
Forecasts of near-average activity result from the expected competing influence of the El Niño-Southern Oscillation (ENSO) climate phenomenon and sea surface temperatures in the equatorial Atlantic during the peak months of the hurricane season (August through October). ENSO is forecast to remain in a weak El Niño phase during this summer, which typically suppresses hurricane activity in the Atlantic. Conversely, ocean temperatures in the tropical Atlantic are expected to be above average through the summer, which historically enhances hurricane activity. Given the uncertainty in forecasting these factors for several months into the future, and because these factors are competing, there is considerable uncertainty as to how they will eventually go on to influence hurricane activity.
Storms can form at any time of year and the North Atlantic has already produced its first named storm of 2019: Andrea formed over open water in the western Atlantic, several hundred miles south of Bermuda, on 20th May. It was a relatively weak and short-lived storm, lasting for less than a day before dissipating. It marked the fifth consecutive year that a storm had formed ahead of the official start date of the hurricane season. There is no historical relationship between the date of the first named storm and the overall seasonal hurricane activity, so the early start to 2019 does not provide any clues as to how the season might pan out.
James Cosgrove, Catastrophe modeler and meteorologist, RMS, comments “These forecasts only provide a guide to the anticipated level of activity across the Atlantic; they do not provide an indication of the expected number of storms to threaten land or make landfall. Although long-term statistics indicate that the probability of a hurricane making landfall in the US increases during more active seasons, there are notable exceptions. 2010 was a particularly active year in the Atlantic basin but only one tropical storm made landfall in the US. Conversely, Hurricane Andrew, one of the most intense and costliest hurricanes in US history, was one of only seven storms to develop during the quiet 1992 season. It only takes one intense landfalling storm to make the season a memorable one.”
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