JACKSONVILLE, Fla – Predicting the onset of rapid hurricane intensification may take a step forward with new research that shows what warning signs to look for before winds jump higher.
High winds are a given in hurricanes, but lighter winds above the storm are required when a hurricane grows stronger. If winds change direction or increase in speed with height this shear can hinder development.
When conditions are right maximum sustained winds can increase at least 35 mph in a 24-hour period which is called RI, or rapid intensification.
“This study could help hurricane forecasting by looking at the hurricane environment in a different way to improve forecasts,” said Hua Leighton, a researcher at NOAA’s Atlantic Oceanographic and Meteorological Laboratory and lead author of the study.
The study describes a power struggle between thunderstorm activity and environmental flow in the upper levels of the atmosphere.
The study showed when persistent thunderstorms in a specific region of the storm overcome the winds in the upper levels and wrap around the storm center, the storm rapidly intensifies. In storms that don’t intensify, the thunderstorms continued to develop but never overcame the prevailing flow.
The winner of this battle between the thunderstorms and the upper-level environmental flow can predict whether a storm will rapidly intensify or not. When the upper-level environmental flow in the specific location is in the opposite direction of the hurricane’s rotation, it tends to inhibit the wrapping around of thunderstorms and prevent the storm from undergoing rapid intensification.
Track predictions over the years have improved becoming 40 percent more accurate than they were just two decades ago. With satellites observing the overall environmental conditions forecasters monitor tropical cyclones for weeks before landfall. But intensity predictions remain tricky because collecting data around the eyewall is complicated.