Weather forecasts give us a good idea on whether a hurricane brewing in the Gulf of Mexico will come our way and how strong it might be when it gets here but they can’t tell us what kind of season lies ahead. For this we must rely on past patterns.
One pattern is called ENSO; short for El Nino-Southern Oscillation. When ENSO is in its cold phase (colder than average ocean temperatures across the equatorial eastern Pacific Ocean) like it was last year, the environment over the Atlantic Ocean is favorable for hurricanes to form. Another pattern is the warming ocean associated with increased greenhouse gases. While a warm ocean does not a hurricane make, given a hurricane over sufficiently warm waters it is likely to get stronger. A third pattern is related to the steering currents. While not important for the number of hurricanes as a whole, they do tell us the chances one (or more) will visit Florida.
So what about this year?
ENSO will be in between a cold and warm phase so I predict an average number of hurricanes (6 or 7). While ocean temperatures continue to increase in the long term, this year they are not likely to be particularly hot (like they were last year) so I expect 2 or 3 major hurricanes (category 3 or above). Finally, the steering currents appear to be somewhat favorable for hurricanes (outside the Gulf of Mexico) to curve away from Florida. While this might seem like good news, the level of predictability using these patterns is modest at best. In fact, the statistical models that I’ve developed [in collaboration with Carl Schmertmann (Department of Economics at FSU)] show us that the forecast skill is limited to about 30% of the year-to-year variation.
Bottom line: Pay attention to the weather forecasts and have a plan if one approaches.
James Elsner is the Earl & Sofia Shaw Professor and Chair of the Geography Department.