A little tropical terminology

It’s only July 10th and we’re already dealing with our 6th named system. I said in my Atlantic Outlook, this would be a hyperactive year in the Atlantic Basin, and so far, that is surely true.

I’ve been using certain terms that apply to the tropical activity so far this season, and I know other outlets and your local weather outlet is also using certain terms. I want to quickly go through the most common terms all y’all will here this season. I’m sure y’all know some of them, but maybe not all of them. So here we go.

TROPICAL CYCLONE
This is the generic term for tropical depressions, tropical storms, and hurricanes.

A tropical cyclone can’t be attached to a warm or cold front. It must have a warm core (air is warmer in center of the cyclone than elsewhere), and persistent deep convection wrapped close to the center. This has their strongest winds closely wrapped around the center This deep convection and the warm SST under it and evaporation from the ocean are how tropical cyclones develop and strengthen.

These are the attributes commonly referred to as tropical characteristics

There are three types of tropical cyclones.

TROPICAL DEPRESSION
A tropical depression is an area of low pressure accompanied by thunderstorms with a closed center of circulation producing maximum sustained winds 23-38 miles per hour. A depression does not get a name, while a storm does.

TROPICAL STORM
A tropical storm is a very powerful tropical weather system. A tropical storm has deep low pressure, allowing for sustained surface wind speeds ranging from 39 to 73 mph. They also have very heavy rainfall leading to coastal and inland flooding. Tropical storms are less powerful than hurricanes, but they’re still very disruptive and dangerous.

HURRICANE
A hurricane is a tropical cyclone in which the extreme low pressure at the center allows for the maximum sustained surface wind speed to be at least 74 mph. Hurricanes come in five categories based on wind strength. Cat 1 has max sustained winds of 74-95 mph, Cat 2 has winds 96-110 mph, Cat 3 has winds of 111-129 mph, Cat 4 has winds of 130-156 mph, Cat 5 has winds that are 157 mph or higher.

A typhoon is the same thing in the western Pacific in East Asia. They’re called cyclones in South Asia and the Indian Ocean. The same storm is called willy-willies in Australia. They all develop in the same way, have the same characteristics

INVEST
Is an area of disturbed weather that is becoming much more organized, the National Hurricane Center will designate this area as an Invest (short for investigative area). Each invest is assigned a number from 90–99, such as “Invest 90L,” with numbers repeating after 99 is reached. The letter identifier tells us the body of water, such as L for Atlantic (A is reserved for the Arabian Sea) and E for Eastern Pacific.

TROPICAL WAVE
These are little low-pressure disturbances (troughs) and move east to west. They can also be called an easterly wave; since they move off the African Coast into the Atlantic, they can also be called an African easterly wave. On satellite they look like unorganized cluster of thunderstorms. There are a lot of tropical waves every season, a small percentage of which develop into tropical cyclones.

TROPICAL DISTURBANCE
This is a generic term for weather disturbances in the tropics and subtropics, as I said above it’s another name for a tropical wave. A tropical disturbance consists of unorganized but persistent convection and sometimes low pressure. It can become a tropical cyclone down the road.

TROPICAL LOW
Sometimes the term tropical low will be used when an invest becomes strong and fairly organized before it becomes a tropical cyclone. The term can also be used sometimes to describe low pressure that is no longer, officially a tropical cyclone.

POST-TROPICAL CYCLONE
This is when a tropical cyclone starts to lose its tropical characteristics. A post tropical cyclone can be either become extratropical or a remnant low. One important thing to remember becoming post tropical doesn’t mean the storm any less dangerous. In fact, Post Tropical Cyclones, like Sandy, can have winds well over Hurricane force.

EXTRATROPICAL CYCLONE
A non-tropical cyclone. Extratropical cyclones get their energy primarily from the imbalance between air masses of different temperatures. Tropical cyclones often become extratropical, undergoing extratropical transition, as they move out of the tropics or subtropics; and once in a while an extratropical cyclone can transition into a tropical one.

SUBTROPICAL CYCLONE
Subtropical Cyclones are a mixture of the characteristics of a tropical cyclone and some characteristics of an extratropical cyclone. Which is why they are often called a hybrid. So, while they’re not a true extratropical cyclone; they’re not fully a tropical cyclone either. Subtropical cyclones, although non-frontal like tropical cyclones, are typically associated with cold upper troughs rather than warm upper ridges, their warm cores are shallower than those of tropical cyclones, and their strongest winds are not as closely wrapped around the center.

REMNANT LOW
A tropical low which was once a tropical cyclone.

EYE
As tropical cyclones become stronger, eyes form, which are in the center of circulation and have relatively less wind and precipitation. Eyes are not seen often in tropical storms or even sometimes in weak hurricanes.

EYEWALL
Circular band of strong winds and heavy rain surrounding the eye. The highest wind speeds are usually in the eyewall.

STORM SURGE
storm surge is rapidly rising water that is pushed onshore and moves inland by the force of the wind accompanying a tropical cyclone. storm surge is often the greatest threat to life and property from a tropical cyclone.

STORM TIDE
The water level rise resulting from the astronomical tide combined with the storm surge.