1.1 Tropical Cyclone Prediction and Predictability: Advances and Challenges (Core Science Keynote Talk) (Invited Presentation)

Wednesday, 25 January 2017: 8:00 AM
Conference Center: Skagit 5 (Washington State Convention Center )
Kerry Emanuel, MIT, Cambridge, MA

Errors in forecasts of tropical cyclone tracks have decreased at all lead times over the past four and a half decades, thanks to improved observations, tropical cyclone models, and initialization techniques, and also to improvements in the skill with which the large-scale environmental flow is forecast. I will present evidence that we are now close to the limit of tropical cyclone track forecast skill imposed by limits of the predictive skill of the large-scale environmental flow, so that further increases in tropical cyclone track forecast skill will probably be tied to increases in the skill with which large-scale environmental winds are forecast.

At the same time, forecasts of Atlantic tropical cyclone intensity have improved little over the past 25 years. I will present evidence that, in contrast to track forecasts, we are currently far from fundamental predictability limits on tropical cyclone intensity, and that at lead times of a few days and less, this is mostly owing to some combination of model error and errors in the initial condition. At longer lead times, intensity errors become increasingly dominated by track errors and errors in forecasts of the large-scale environmental wind shear. Partly for this reason, I will advocate for a migration away from the traditional track-intensity pair to probabilistic prediction of winds at fixed points in space, which are more societally relevant.

The talk will finish with a discussion of seasonal prediction and centennial projection of tropical cyclone activity.

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