The 2017 North Atlantic Hurricane Season: Penn State ESSC Forecast

ESSC scientist Michael E. Mann, alumnus Michael Kozar, and researcher Sonya K. Miller have released their seasonal prediction for the 2017 North Atlantic hurricane season, which officially starts on June 1st and runs through November 30th.

The prediction is for 15.3 +/- 3.9 total named tropical cyclones, which corresponds to a range between 11 and 20 storms with a best estimate of 15 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 (0.81 °C in late-April 2016 from NOAA’s Coral Reef Watch) throughout the 2016 hurricane season, (b) neutral ENSO conditions in the equatorial Pacific during boreal Fall/Winter 2017-18 (Climate Prediction Center April 2017 ENSO Discussion), and (c) climatological mean conditions for the North Atlantic Oscillation in Fall/Winter 2017-18.

If a mild El Niño develops (Niño3 anomaly around 0.5 °C), then the prediction will be lower: 14.1 +/- 3.8 storms (range of 10-18 storms with a best guess of 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 slightly lower prediction (12.4 +/- 3.5 total named storms). This alternative model also includes neutral ENSO conditions.

Previous Forecasts:

Year (click to see forecast)
Prediction
Best Guess
Range
Actual Count
2007 n/a 15 n/a 15
2009 11.5 +/- 3.4 12 8-15 (6-13 if El Niño) 9
2010 23.4 +/- 4.8 23 19-28 19
2011 16.25 +/- 4.0 16 12-20 19
2012 11.2 +/- 3.3 11 8-15 19
2013 16.0 +/- 4.0 16 12-20 14
2014 9.3 +/- 3.0 9 6-12 8
2015 6.9 +/- 2.6 7 4-10 11
2016 18.9 +/- 4.4 19 14-24 15

References:       
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.

Footnotes:

The tropical cyclone series was corrected based on an estimated historical undercount taken from Vecchi and Knutson (2008).

Prediction made: 25 April 2017

This webpage last updated: 28 April 2017