Hurricane Research
2011 FSU COAPS Atlantic Hurricane Season Forecast |
 Animation: The 2011 Hurricane Season in 4.5 minutes. Credit: NOAA |
2011 FSU COAPS Atlantic Hurricane Season Forecast
On June 1, 2011, COAPS scientists released their third annual Atlantic hurricane season forecast. Their 2011 forecast called for a 70 percent probability of 14 to 20 named storms and 7 to 11 hurricanes. The mean forecast was for 17 named storms, 9 hurricanes, and an accumulated cyclone energy (ACE; a measure of the strength and duration of storms) of 162. These numbers are slightly above the 1995-2010 average of 14 named storms and 8 hurricanes, and reflect above normal tropical North Atlantic sea surface temperatures, below normal sea surface temperatures in the equatorial Pacific (La Niña conditions), and the ongoing positive phase of the Atlantic Multi-decadal Oscillation.
The observed number of tropical storms in the Atlantic during the 2011 season was 19, 18 of which were named, and 7 of which were hurricanes. The ACE was 123.
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 vastly different from the statistical methods used by other seasonal hurricane forecasters. The COAPS 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 on 1 June.
The COAPS forecast is already gaining recognition for its accuracy only two 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. Details about past forecasts are archived here.
To learn more about this forecast, contact lead scientist Tim LaRow (; (850) 644-6926) and see the following article:
- 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.
2011 Atlantic hurricane season predictions and observed activity.
| Forecasting Group | Forecasting Method | Forecast Issue Date | Total Named Storms (Tropical Storms + Hurricanes) | Hurricanes | Accumulated Cyclone Energy |
| FSU COAPS | Dynamical | 6/1/11 | 17 (70% chance of 14-20) | 9 (70% chance of 7-10) | 163 (70% chance of 130-183) |
| NOAA | Hybrid | 5/19/11 | 12-18 | 6-10 | 105%-200% of 1981-2010 median |
| UK Met Office | Dynamical | 5/26/11 | 13 (70% chance of 10-17) | N/A | 151 (70% chance 82-212) |
| Colorado State University | Statistical | 6/1/11 | 16 | 9 | 160 |
| Tropical Storm Risk | Statistical | 6/6/11 | 14.1 (+/-3.4) | 7.6 (+/-2.4) | 123 (+/-48) |
| Observed* | N/A | N/A | 18 (19 total tropical storms) | 7 | 123 |
*For the latest updates on 2011 hurricane activity, visit the National Hurricane Center.
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