Analysis of Hurricane Katrina's outflow layer after landfall suggests that it does not comprise the long-lived midlatitude warm pool. Instead, it curls anticyclonically and re-enters the tropical warm source region east of Florida. However, the interaction between Katrina's anticyclonic outflow and an approaching baroclinic trough is shown to establish an anomalous southwesterly conduit that injects a pre-existing warm pool over the southwestern United States into the midlatitudes. This warm pool reduces predictability in medium-range forecasts over the North Atlantic and Europe while simultaneously aiding in the development of Hurricanes Maria and Nate.
The origin of the warm pool is shown to be the combination of anticyclonic upper-level features generated by Eastern Pacific Hurricane Hilary and the South Asian Anticyclone. The global nature of the connections involved with the development of the warm pool and its injection into the extratropics has an impact on forecasting since the predictability issue associated with ET in this case involves far more than the potential reintensification of the transitioning system itself.