Even the strongest hurricanes churning in the tropics can quickly be reduced to a small patch of showers in the presence of vertical wind shear.
Many factors can cause westerly wind shear in the tropics.
The most common are upper-level troughs near the hurricane and a strong El Nino episode in the Pacific. The effects from all causes is the same in that the tops of the thunderstorms that feed hurricanes are often chopped off. This quickly weakens hurricanes. Gannett Co. Inc. Shop.