It’s a confusing time when a hurricane threatens, and some terms used by officials aren’t known by everyone, so here’s a storm glossary.
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glossary → ’ → everyone
Let’s start with the broad category of these storms, called tropical cyclones.
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’s → start → storms
In the northern hemisphere, a tropical cyclone is a rapidly counterclockwise-rotating storm that forms in Earth’s warmer areas that is organized with a center that winds flow out of.
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winds → rotate → that
Tropical cyclones rotate clockwise in the southern hemisphere.
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cyclones → rotate → hemisphere
The strongest tropical cyclones in the Atlantic and eastern and central Pacific oceans are called hurricanes.
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cyclones → call → Atlantic
In the northwest Pacific they are called typhoons and in the south Pacific and Indian oceans they are called cyclones or tropical cyclones.
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they → call → Pacific
Tropical depressions, tropical storms
In the Atlantic, the weakest of these systems are called tropical depressions.
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weakest → call → systems
They have winds of less than 39 mph (63 kph).
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They → have → mph
When a tropical depression reaches 39 mph (63 kph) but is weaker than 74 mph (119 kph) they are called tropical storm and receive a name from a pre-established list.
Category 1 and 2 hurricanes
When a tropical storm hits 74 mph (120 kph), it achieves hurricane status.
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it → reach → status
The weakest is a Category 1, with winds of 74-95 mph (120-150 kph) and it will have dangerous winds that produce some damage.
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that → have → damage
Tree branches will snap and some will be uprooted.
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some → snap → ?
A Category 2 has winds of 96-110 mph (155-175 kph) and can be disastrous, with near-total power loss expected near the center.
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Category → have → center
Major hurricanes: Category 3, 4 and 5
When hurricanes sustain winds exceeding 111 mph (180 kph), they get major hurricane status, with devastating consequences.
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they → sustain → consequences
Even well-built homes may be severely damaged by a Category 3 hurricane with winds of 111-129 mph (180-210 kph).
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homes → build → mph
A Category 4 hurricane is considered catastrophic, with winds of 130-156 mph (210-250 kph) that leave entire areas uninhabitable for weeks or months.
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that → consider → weeks
The scale tops out at Category 5, when a hurricane’s winds exceed 157 mph (250 kph).
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winds → top → mph
A high percentage of the homes in the disaster region will be destroyed.
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percentage → destroy → region
Power outages could last for months.
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outages → last → months
Storm surge and tide
Storm surge is the deadly rise of water generated by a storm that’s above and beyond the normal tide.
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that → generate → tide
It starts in the ocean but could include rivers and canals.
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It → start → rivers
Storm surges once caused nearly half of a hurricane’s deaths, but surge-related fatalities have come down with warnings and education to about 11% of all direct deaths.
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fatalities → cause → deaths
Surges can reach as much as 20 feet or more and that does not include waves, which are on top of storm surge.
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which → reach → surge
Eye and eyewall of hurricane
A hurricane’s center is called the eye.
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center → call → hurricane
After awhile, a storm can form a new second eyewall around the first in a process called eyewall replacement that temporarily weakens the storm’s intensity but enables it to grow larger overall.
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it → form → intensity
When an area on the ground is hit by the eyewall, it will be buffeted by intense winds, then get a break before being slammed by the other side of the eye in a second round of the storm’s strongest winds.
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it → hit → winds
Landfall
When the eye of a hurricane or tropical storm goes over land, that point is called landfall.
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point → go → land
But high winds, rain and storm surge can cause all sorts of damage many hours before landfall, and last many hours thereafter.
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winds → cause → landfall
Landfall is not necessarily where the strongest winds are, and the wider swirl of a storm can spread destruction across large areas.
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swirl → spread → areas
Dirty side of a hurricane
The right front quadrant of a hurricane or northeast part of the eyewall tends to cause the most damage as the strongest winds blow counterclockwise around the center, so this at times is called a storm’s dirty side.
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this → tend → times
In the southern hemisphere, it’s the left front quadrant that is the dirty side.
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that → ’ → hemisphere
Forecast and spaghetti models
There are dozens of computer generated models that forecast changes in each storm’s track and intensity.
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that → be → track
They vary because each one uses different assumptions about how storms operate and some prove better during certain storms and worse during others.
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some → vary → others
Forecasters advise to avoid concentrating on one individual model.
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Forecasters → advise → model
When many or all of the models are put on one map, they generally show an overall sense of what will happen.
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what → put → sense
Sometimes they show a lot of lines going in different directions, which can look like cooked spaghetti.
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which → show → spaghetti
The National Hurricane Center’s official forecast is not one specific line, but rather a cone of uncertainty that expands with time, up to five days out.
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that → expand → time
That cone shows the most probable area where the eye of the storm could move over time, but it doesn’t mean the storm will be in the center of that cone.
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storm → show → cone
It is designed so that 67% of the most likely tracks fall within the cone.
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% → design → cone
Watches and warnings
A hurricane or tropical storm watch means conditions are possible within an area during the time specified by the National Weather Service.
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conditions → mean → Service
A hurricane or tropical storm warning means those conditions are no longer just possible, but expected.
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conditions → mean → ?
…and 5 more, not listed.
The Aporia
