Houston is quite familiar with tropical cyclones. Within the past couple of years, we have seen multiple systems affect our area, such as Hurricanes Beryl and Harvey, along with tropical storms like Imelda and Beta.
Classifications
When classifying these storms, the major factor taken into account is the wind. Tropical depressions have winds of less than 38 mph; tropical storms have winds of 39 - 73 mph. Hurricanes themselves are classified into five separate categories as seen below.
Hurricane Hunters
Hurricane hunters are a team of aircraft crews that fly into tropical systems with different weather instruments to investigate the structure of these storms.
One of these instruments is the dropsonde, which, as its name implies, is dropped into the storm to measure pressure, humidity, and windspeed. The hunters will often fly from different directions into the storm to collect data from all parts of the storm.
Satellite
Now, of course, in the U.S., we have the aforementioned Hurricane Hunters who fly into these dangerous storms. What about when these systems are over the middle of the ocean?
That’s when satellite comes in handy. By using satellite to observe different features of a system, such as the eye, banding features, and the central dense overcast, we can estimate the intensity of the system. The eye is the center of the hurricane, where skies are often calm, and the pressure is the lowest. The banding feature, or rain bands, are the outer swirling areas of rain rotating around the center.
Lastly, the central dense overcast is the area surrounding the center with thick cirrus accompanied by thunderstorms. These three features can help estimate winds peeds of tropical systems from satellite observations.
Buoys
Buoys are another way of measuring wind speeds, especially closer to home. Buoys are small floating devices in the water that can be used to take observations like wave heights and wind speeds.
Oftentimes, when a tropical system passes over, we can use these surface readings to measure the wind speeds. Of course, there are other ways to measure these wind speeds as well, but we in Houston should always be prepared for tropical systems.
As we know, other hazards such as rainfall and storm surge can be more dangerous and deadlier than winds. As always, we will continue to keep you updated on the tropics, so stay tuned.