2010 hurricane season predictions reviewed
May 12, 2011
When reports like those by Corelogic come out, you know hurricane season is around the corner. As the season nears, the predictions of what the season will be start to arrive. (Verily, North Carolina State’s 2011 Outlook is already out). Having not yet closed out the 2010 season, I will do so now.
While 1992 is the canonical “quiet” season that ended up being quite memorable due to the category 5 landfall of Hurricane Andrew, 2010 may be the canonical example of an active season that ended up being forgettable in the United States.
The 2010 Atlantic hurricane season produced 19 named storms, of which 12 became hurricanes and five became major hurricanes. This was above long and short-term average activity and in line with expecations. No one was off by more than two storms. NOAA’s forecast was the most accurate, as the mean of their forecast range was 19/11/5. This was clearly the best performance of the consensus forecast in the past five years (I shall explain in a moment why 2007 isn’t as impressive as it looks).
|5 season trailing average||15/7/4||17/8/4||17/8/4||17/8/4||17/9/5||16/7/4|
Another way of measuring activity is Accumulated Cyclone Energy, which gives us an idea of how strong and/or long-lived the storms were. Units are 10,000 knots squared.
|5 season avg||137||164||158||160||154||119|
As we can see, the storms were, on aggregate, were a little bit shorter-lived and/or weaker than anticipated **. Florida State’s forecast once again was the most accurate. The consensus figure was fairly close to the mark and easily the best forecast in the past five years. While the 2007 forecasts were in the ball-park as far as the storm totals go, they were completely wrong on the energy sum. As such, the 2010 forecasts were easily the best of recent years.
The high level of activity did not translate into much as far as the United States is concerned, giving many the impression it was a quiet season. No hurricanes made landfall in the United States, making this the most active season in which none did so (though Alex came close, coming in on the northern Mexico coast). Most of the forecasts do not attempt to anticipate landfalls, while those issued by the Colorado State team and Tropical Storm include landfall probabilities in their forecast. CSU’s methodology is directly tied to anticipated storm activity. As they correctly forecasted high levels of activity they anticipated an increased probability of storm landfall. TSR similarly erred by predicting at least two hurricane landfalls in the US.
It should be noted that while it was quiet for the United States, it wasn’t so for many in the Atlantic basin. The afforementionedAlex caused more than $1 billion in damage in Mexico, while Karl left an estimated 40,000 people in that country homeless. Igor was the Newfoundland’s worst damaging hurricane in 75 years and the name was retired. Tomas was also retired after causing a significant amount of damage and deaths in St. Lucia and Haiti.
Links to the forecasts are provided below. Also, several organizations produced a season review including a critique of their forecast along with coverage of the climatic conditions that made the season the way it was. Of these, Colorado State’s is the most comprehensive.
As mentioned at the beginning, the 2011 outlook is already out from NC State’s forecasters. Tropical Storm Risk and Colorado state have issued their extended range forecasts alreay as well, but the forecasts I used above are typically released right around June 1. As the model used by Florida State uses initial conditions from the beginning of hurricane season, their forecast comes out shortly after June 1. The outlook from NOAA’s Climate Prediction Center
is usually released during Hurricane Awareness Week, which this year is May 23-27 will be released Thursday, May 19. Note that the National Hurricane Center is listed as providing input for the forecast, but it is not their product.
** A couple of weak short-lived storms, Bonnie and Gaston, bumped up the tropical storm numbers while having only a very negligible contribution to ACE. In fact, the NHC’s report on the latter concedes “it is possible that Gaston never attained tropical storm strength.”