Coriolis Force helps keep the storm rotating. Instability Hurricanes are made of thunderstorms, and the thunderstorms won't start with the atmosphere being unstable. Therefore, hurricanes rarely form under the subtropical highs, which are quite stable. No Wind Shear Hurricanes are complicated structures. If everything isn't in just the right place, it won't work.
Shear move the heat and the moisture to the wrong parts of the storm, and it falls apart.
An initial disturbance Hurricanes don't just form when conditions are right. Rather, a pre-existing group of thunderstorm has a GROW into a hurricane. This is monsoon season in the tropics, and the monsoon thunderstorms make excellent initial disturbances. The Saffir-Simpson Scale quantifies the strength of the storm based on its wind speed. Typically the most destructive part of the storm.