Colorado State’s 2011 Atlantic Hurricane Season Forecast

June 1, 2011

With the usual caveats that an active season doesn’t necessarily mean your coastal locale will be hit by a hurricane (and vice versa) and that these predictions are research projects in progress.

Today, the father of hurricane season forecasting William Gray and his protege turned project head Phil Klotzbach issued their hurricane season forecast under the auspices of Colorado State University.

Like everyone else, the team anticipates an above average level of activity.  The forecast calls for sixteen tropical storms, nine hurricanes, and five major hurricanes to form in the Atlantic during the forthcoming season totaling an Accumulated Cyclone Energy of 160.  This is a little bit above forecasts of other hurricane season climatology researchers.  As is the case with other forecasts, the key drivers are anticipated neutral conditions from the El Niño Seasonal Oscillation (ENSO) and warmer than normal sea surface temperatures in the tropical Atlantic.

It should be noted that while these forecasts have been issued for 28 years, the methodology has not been static.  In the early forecasts west African rainfall was a key predictor, but its apparent relationship with tropical cyclone activity fell apart after 1995.  In 2008, a substantially revised scheme was introduced. This year’s forecast introduces a new scheme, yet again. The new factors should give a better indication of  ENSO and a more dynamic/accurate sea surface temperature forecast.

Season CSU Named Storms/Hurricanes/Majors Hurricane Forecasts Actual CSU Accumulated Cyclone Energy Forecast Actual
2005 15/8/4 28/15/7 177 248
2006 17/9/5 10/5/2 206 79
2007 17/9/5 15/6/2 170 72
2008 15/8/4 16/8/5 150 145
2009 11/5/2 9/3/2 85 51
2010 18/10/5 19/11/5 185 166

The performance of their forecasts has been roughly similar to that of those issued by other groups.  Despite having the highest prediction for activity in 2005, they still greatly underestimated the scope of the unprecedented 2005 season.  In 2006, their predictions for activity were again the highest, this time though, the unexpected El Niño caused their numbers, like everyone else’s (less NC State’s) to be badly over.  In 2007, their estimate for Accumulated Cyclone Energy was a little bit higher than everyone else’s so once again they had the worst over-forecast.  Their revised forecast scheme in 2008 yielded the best performing prognostication that year, though it was a good season for the forecasters across the board.  In 2009, their forecast for ACE was identical to NOAA’s and over-forecast. 2010‘s predictions  similar to everyone else’s and came out OK.

 The Florida State forecast, which has been a leading performer thus far, has just been released also and will be the subject of my next post.


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