TUTTs sometimes bring a large amount of vertical wind shear over tropical disturbances and cyclones so TUTTs can reduce cyclone development. But, there are also times when TUTTs help start tropical cyclones or make them stronger by providing additional forced ascent near the storm center and an efficient outflow channel in the upper troposphere. Moreover, under specific circumstances, TUTTs can grow into upper cold lows and may enhance the development of low level disturbances.