ESSC scientist Michael E. Mann, alumnus Michael Kozar, and researcher Sonya Miller have released their seasonal prediction for the 2013 North Atlantic hurricane season, which officially starts on June 1st and runs through November 30th.
The prediction is for 16.0 +/- 4.0 total named tropical cyclones, which corresponds to a range between 12 and 20 storms with a best estimate of 16 named storms. This prediction was made using the statistical model of Kozar et al. (2012, see PDF here). This statistical model builds upon the past work of Sabbatelli and Mann (2007, see PDF here) by considering a larger number of climate predictors and including corrections for the historical undercount of events (see footnotes).
The assumptions behind this forecast are (a) the persistence of current North Atlantic Main Development Region (MDR) sea surface temperature (SST) anomalies (0.87°C in May 2013 from NOAA’s Coral Reef Watch) throughout the 2013 hurricane season, (b) a continuation of near-neutral conditions in the equatorial Pacific during boreal Fall/Winter 2013-14 (Climate Prediction Center ENSO Discussion), and (c) climatological mean conditions for the North Atlantic Oscillation in Fall/Winter 2013-14. Using an alternative model that uses "relative" MDR SST (MDR SST with the average tropical mean SST subtracted) in place of MDR SST yields a very similar prediction (15.1 +/- 3.9 total named storms).
In 2007, Mann and alumnus Thomas Sabbatelli correctly predicted the exact number of named tropical cyclones (15) for that season (Sabbatelli and Mann 2007). Mann and Sabbatelli predicted 8 to 15 named storms in 2009, with a lower range of 6 to 13 in the event of a strong El Niño (Niño3 anomaly +1 C or greater, see 2009 prediction). The 2009 season was relatively quiet with 9 named storms partially due to the development of the anticipated strong El Niño. In 2010, Mann and Kozar predicted between 19 and 28 named storms, with a best estimate of 23 storms (see 2010 prediction). The National Hurricane Center identified 19 named storms during the 2010 Atlantic Hurricane Season. The prediction of 12 to 20 storms in 2011 (best guess of 16) was also on target as there were 19 tropical cyclones during the 2011 season (see 2011 prediction). Finally, last year, Mann and Kozar predicted between 8 and 13 storms (see 2012 prediction). However, the 2012 season was more active than anticipated with 19 storms for the third straight year, as El Niño conditions failed to develop.
Kozar, M.E., Mann, M.E., Camargo, S.J., Kossin, J.P., Evans, J.L., 2012: Stratified statistical models of North Atlantic basin-wide and regional tropical cyclone counts, J. Geophys. Res., 117, D18103, doi:10.1029/2011JD017170.
Mann, M.E., Sabbatelli, T.A., Neu, U., 2007: Evidence for a Modest Undercount Bias in Early Historical Atlantic Tropical Cyclone Counts, Geophys. Res. Lett., 34, L22707, doi:10.1029/2007GL031781.
Sabbatelli, T.A., Mann, M.E., 2007: The Influence of Climate State Variables on Atlantic Tropical Cyclone Occurrence Rates, J. Geophys. Res., 112, D17114, doi: 10.1029/2007JD008385.
Vecchi, G.A., Knutson, T.R., 2008: On Estimates of Historical North Atlantic Tropical Cyclone Activity, J.Climate, 21, 3580-3600, doi:10.1175/2008JCLI2178.
Last Updated: 31 May 2013