HOUSTON (CW39) – The environment that Tropical Depression NINE is entering into over the next 24 hours is very favorable for tropical development.
What creates a good environment for a hurricane?
Warm waters are essential for hurricanes to form. Water temperatures over 80 degrees F are normally needed for development. Warm water is the main source of energy for a tropical system as it will spawn more evaporation to occur at the water’s surface.
Not only does the water need to be warm, but it needs to be DEEP and warm. As a hurricane churns over the ocean, or in this case, the Gulf of Mexico, a process called upwelling occurs. The water at surface is dislocated by the winds and strength of the storm, to fill in the gap, waters that are further beneath the surface move up to fill the void. If this water is much cooler, then it will limit development. If it is similar in temperature, then it is more likely that the storm will continue to strengthen. Therefore, depth of warmth matters!
Hurricanes also want LOW vertical wind shear. Wind shear is the change in winds with height. This means that you do not want anything major occurring in the upper atmosphere to throw off the vertical development in a storm. “Boring” weather days are good for development. Any type of cold front or passing upper-level disturbance can tear apart a smaller scale cyclone.
A cooling vertical profile is also wanted by storms. We say it all the time, “warm air rises”! There are examples of this all throughout your day-to-day life. It is why the upper-level floors of your home are warmer than the lower levels. It is how hot air balloons get up into the air!
However, there is more to the statement “warm air rises”. Warm air rises in regard to the surrounding air. As a parcel of air moves upward within the storm it will continue to rise until it is no longer warmer than its surroundings. Therefore, we want there to be a steady temperature decline as we travel up into the storm, no warm pockets! This way the rising air will continue to aid in storm development.