The Inner-Core Temperature Structure of Hurricane Edouard (2014): Observations and Ensemble Variability Monthly Weather Review

The inner-core thermodynamic structure of Hurricane Edouard (2014) is explored, primarily through an examination of both high-altitude dropsondes deployed during NASA'sHurricane and Severe Storm Sentinel (HS3) and a 60-member convection-permitting ensemble initialized with an ensemble Kalman filter. The 7-day forecasts are initialized coincident with Edouard's tropical depression designation and includeEdouard's significant intensification to a major hurricane. Ten-member ensemble groups are created based on timing of near-rapid intensification (RI) onset, and the associated composite inner-core temperature structures are analyzed. It is found that at Edouard's peak intensity, in both the observations and the simulations, the maximuminner-core perturbation temperature (similar to 10-12 K) occurs in themidlevels (similar to 4-8 km). In addition, in all composite groups that significantly intensify, the evolution of the area-averaged inner-core perturbation temperatures indicate that weak to moderate warming (at most 4K) begins to occur in the low tomidlevels (similar to 2-6 km) similar to 24-48 h prior to RI, and this warming significantly strengthens and deepens (up to similar to 8km) similar to 24 h after RI has begun. Despite broad similarities in the evolution of Edouard's warm core in these composites, variability in the height and strength of the maximum perturbation temperature and in the overall development of the inner-core temperature structure are present among the members of the composite groups (despite similar intensity time series). This result and concomitant correlation analyses suggest that the strength and height of the maximum perturbation temperature is not a significant causal factor for RI onset in this ensemble. Fluctuations in inner-core temperature structure occur either in tandem with or after significant intensity changes.