Hurricanes are fed by energy from the warm ocean. The center of a hurricane is surrounded by tall clouds, called cumulus clouds, that produce the heat needed to keep the spin, what we call vorticity, in the hurricanes going. When there are a lot of cumulus clouds around the hurricane’s center, the hurricane spins more rapidly. However, when there is a large change in the wind speed or direction with height (called wind shear), the cumulus clouds and their heating and vorticity can be pushed away from the hurricane’s center. This usually causes hurricanes to weaken, but some can still strengthen when the wind shear is high, challenging hurricane forecasters. This study reviews the problem of forecasting hurricane intensity using NOAA’s Hurricane Weather Research and Forecasting system and explains how a storm can intensify when the wind shear is high.
Important Conclusion:
- Individual cumulus clouds move around the hurricane’s center with the wind (for example, counter-clockwise north of the Equator). When the wind shear is high, if groups of cumulus clouds form in the downshear direction (usually the direction the wind at the top of the hurricane blows toward) and then move into the upshear direction (usually the direction where the wind at the top of the hurricane blows from), the vorticity created may be enough to rapidly intensify the hurricane.
The article can be found at https://metnet.imd.gov.in/imdmausam/