Practical Uncertainties and Underlying Dynamics in the Limited Predictability of the Record-Breaking Intensification of Hurricane Patricia (2015)

Hurricane Patricia (2015) was a record-breaking tropical cyclone that was difficult to forecast in real-time by both operational numerical weather prediction models and operational forecasters. The current study examines the potential for improving Patricia’s intensity prediction through convection-permitting assimilation of airborne Doppler radar radial velocity observations with an ensemble Kalman filter (EnKF), decreasing the model horizontal grid spacing down to 1 km, and reducing the surface drag coefficient at high wind speed in the parameterization of the sea surface-atmosphere exchanges. The practical predictability of Patricia, its peak intensity and rapid intensification, as well as the underlying dynamics are further investigated through a high resolution 60-member ensemble initialized with realistic initial-condition uncertainties represented by the EnKF osterior analysis perturbations. Most of the ensemble members are able to predict the peak intensity of Patricia, but with large uncertainty in the timing of the rapid intensification; some members fail to reach the ultimate peak intensity before making landfall. The ensemble sensitivity analysis shows that the initial uncertainty in the region just outside of the radius of maximum wind contributes most to the difference in Patricia’s intensification. Ensemble members with stronger initial primary and secondary circulations beyond the radius of maximum wind intensify earlier, are able to maintain the intensification process for a longer period, and thus reach greater and earlier peak intensity.