Hurricanes sometimes change intensity very quickly, and if this happens when they approach land, it can suddenly cause a lot of damage or kill many people. This so-called Rapid Intensification (RI) is very hard to forecast. For the first time, the Hurricane Weather Research and Forecast (HWRF) model that NOAA uses to forecast where a hurricane will go and how strong it will be, was used to help understand RI. During RI, the HWRF forecasts matched information from aircraft in hurricanes.
Important conclusions:
- Sometimes, the position of the hurricane eye changes with height. It was thought that this change needed to disappear before RI began, but, in this case, it does not disappear until a few hours after RI begins.
- Hurricane eyes are warm in the middle and upper parts of the atmosphere, and the amount of warmth is tied to intensity. The eyewall is the ring of strong thunderstorms surrounding the eye that fuel the hurricane winds. When the thunderstorms get especially strong in a special part of the eyewall, they can help to transfer more warm air into the eye and lead to further intensification.
The paper can be accessed at http://journals.ametsoc.org/doi/abs/10.1175/JAS-D-14-0097.1.