Weather Glossary

what is a snow squall

What are Snow Squalls?

TWSE Explains

It happens every winter. Drivers are caught off guard by icy roads and a sudden wind gust, the arrival of cold air, and a burst of snow so heavy you can't see the car in front of you. It's called a snow squall and is more common than people think.

tropical depression

Hurricanes, Tropical Storms, and Tropical Depressions

TWSE Explains

Mother Nature can be both awe-inspiring and terrifying. Among her most powerful and destructive forces are tropical cyclones, which manifest ...

realfeel temperature

What is the RealFeel Temperature?

TWSE Explains

Weather forecasts provide valuable information about the expected temperature and weather conditions. However, the actual temperature can sometimes differ from ...


What is a Microburst?

TWSE Explains

Weather is a complex and fascinating subject, with numerous phenomena occurring all around the globe. One such event, a microburst, ...

what is a superbloom? Picture of a california superbloom of wildflowers.

What is a Superbloom?

TWSE Explains

In the arid deserts and valleys of the Western United States, a rare and magnificent natural event occasionally graces the ...

outflow boundary shelf cloud

What is an Outflow Boundary?

TWSE Explains

An outflow boundary is a meteorological term that refers to the boundary between two air masses created by a thunderstorm's downdraft. If you've ever stood outside during a thunderstorm and felt the cool rush of air preceding a storm, you've experienced an outflow boundary.

types of fronts weather map header image

Types of Fronts

Ed Oswald

Ever wonder what the types of fronts you see on the weather map mean? As part of our continuing weather education series, we thought an explainer would be helpful.

Satellite view of cloud formations over the Earth.

What is an Atmospheric River?

TWSE Explains

Our atmosphere is constantly in motion. Weather systems are transported around the globe by this motion, with a narrow band of stronger winds called the ‘jet stream‘ providing much of this motion, which lies between cold and warm air masses.

cloud types cumulus

What’s the Difference Between Weather and Climate?

TWSE Explains

When most people think about the weather, they're thinking about conditions in the short term—the current temperature, what it's like outside, and whether or not it looks like it's going to rain. On the other hand, climate refers to average weather conditions in a particular area over time.

sleet in a glove

What is Sleet?

TWSE Explains

In the average winter, most of us will have to deal with frozen precipitation, not just snow. One of these types is sleet, and we'll explain how it forms and the difference between it and a hailstone.

polar vortex diagram

What is a Polar Vortex?

Ed Oswald

Winter 2020-21 didn’t turn out as many thought. Most long-range forecasters thought La Niña would lead to a mild and uneventful winter. My weather station read 62 on Christmas Day in Pennsylvania! Well, the polar vortex had other plans.

noreaster satellite image

What is a Nor’easter?

TWSE Explains

Nor'easters are intense periods of snow and high wind that can last for days. While the term is most commonly associated with coastal storms that pass by the Northeastern US' major cities, the term is used elsewhere, such as in Europe.

sleet vs freezing rain ice on branches

Sleet vs Freezing Rain vs Hail

TWSE Explains

Sleet vs freezing rain: which winter weather phenomena would you rather deal with? While both create a whole host of headaches, one is far more hazardous than the other.

isolated vs scattered thunderstorms blog header

The Difference Between Isolated and Scattered Thunderstorms

TWSE Explains

When most people think of thunderstorms, they imagine a large, dark storm cloud that pops up in the afternoon and evening, bringing strong winds and heavy rain. This type of storm is called an air mass thunderstorm. However, two other types of thunderstorms often precede frontal passages in the summer.

squall line in illinois

What is a Squall Line?

TWSE Explains

A squall line is a line of strong and severe thunderstorms common in the spring and summer and often produce strong winds, lightning, heavy rain, and hail. Squall lines often form ahead of cold fronts but can develop independently if several strong thunderstorms merge.

ice on car from freezing rain

What is Freezing Rain?

TWSE Explains

We've all been through it if you live in an area that falls below freezing in winter. It's freezing out yet raining. Within minutes, everything becomes an ice rink. Drivers lose control of their cars, everything grinds to a halt. It's not fun.

blizzard in manhattan

What is a Blizzard?

TWSE Explains

A blizzard is a severe snowstorm that produces extensive wintry precipitation over a large area, including heavy snow and powerful winds, typically accompanied by freezing temperatures.

Colorful jet stream visualization over Earth's Western Hemisphere.

What is the Jet Stream?

TWSE Explains

The jet stream is a narrow band of strong winds in the upper levels of Earth’s atmosphere, and it blows from west to east and provides a corridor for storms to follow as they circumnavigate the globe. Jet streams form along the boundaries of warm and cold air, and the wiggles of the jet stream play a large part in the weather you experience.