FSU COAPS Atlantic Hurricane Season Forecast

COAPS scientists expect to release their fifth annual Atlantic hurricane season forecast on Friday, May 31, 2013.

Last year's forecast called for a 70 percent probability of 10 to 16 named storms and 5 to 9 hurricanes. The mean forecast was for 13 named storms, 7 hurricanes, and an average accumulated cyclone energy (ACE; a measure of the strength and duration of storms) of 122. These numbers were based on 51 individual seasonal forecasts conducted since May 25, 2012 using sea surface temperatures predicted by NOAA.

The forecast mean numbers were slightly below the 1995-2010 average of 14 named storms and 8 hurricanes, and reflected the possible emergence of El Niño conditions in the tropical Pacific and cooling surface water temperatures in the tropical North Atlantic.

The scientists use a numerical atmospheric model developed at COAPS to understand seasonal predictability of hurricane activity. The model is one of only a handful of numerical models in the world being used to study seasonal hurricane activity and is different from the statistical methods used by other seasonal hurricane forecasters. FSU is the only university in the United States issuing a seasonal hurricane forecast using a global numerical atmospheric model. The model uses the high performance computers at FSU to make predictions of the atmosphere six months into the future. Based on these atmospheric predictions, tropical activity is objectively determined and forecasts are issued around June 1st.

The COAPS forecast is already gaining recognition for its accuracy only three years after its launch. The 2009 forecast predicted 8 named storms and 4 hurricanes, and there ended up being 9 named storms and 3 hurricanes that year. The 2010 forecast predicted 17 named storms and 10 hurricanes, and there were actually 19 named storms and 12 hurricanes. The 2011 forecast predicted an average of 17 named storms and 9 hurricanes, and there were actually 19 named storms and 7 hurricanes. Re-forecasts conducted using data since 1982 shows that the model has a mean absolute error of 1.9 hurricanes and 2.3 named storms. Details about past forecasts are archived here.

To learn more about this forecast, contact lead scientist Tim LaRow ( This email address is being protected from spambots. You need JavaScript enabled to view it. ; (850) 644-6926) and see the following article:

• LaRow, T. E., 2013: The impact of SST bias correction on North Atlantic hurricane retrospective forecasts. Monthly Weather Review, 141, 490-498, doi:10.1175/MWR-D-12-00152.1.
• LaRow, T. E., L. Stefanova, D. W. Shin and S. Cocke, 2010: Seasonal Atlantic tropical cyclone hindcasting/forecasting using two sea surface temperature datasets. Geophys. Res. Lett., 37, L02804, doi:10.1029/2009GL041459.

2013 Atlantic hurricane season (June 1 - November 30) predictions and observed activity.

*For the latest updates on hurricane activity, visit the National Hurricane Center.

The International Research Institute for Climate and Society (IRI) also releases a forecast for the abbreviated August 1 - October 31 peak Atlantic hurricane season. The IRI forecast can be found at http://iri.columbia.edu/forecast/tc_fcst/north_atlantic/.