What do these weather terms mean?

Watching the weather means viewing lots of maps and graphics, but it also means hearing lots of terminologies. To understand what's going on and what's ahead, it's important that you also understand what those different terms mean as you plan your day.

To help you out, we've assembled a list of weather terms that you may not understand even though you may hear them very often. Others may be very familiar but have a slightly different meaning than you might think. Either way, we're bringing it all together right here.

What a Blizzard Really Is...And Isn't

Everybody has probably been stuck out in a blustery, blinding snow event and referred to it as a "blizzard." The word helped communicate just how harsh conditions were, but the true definition of a blizzard is fairly strict. To be considered an actual blizzard, the event must feature winds sustained or frequently gusting at 35mph and snowfall heavy enough to consistently reduce visibility to a quarter-mile or less. Those conditions must be sustained for at least three hours to constitute a real blizzard. Earlier definitions had a temperature requirement as well, but recent updates have removed that parameter and defined a blizzard only in terms of snowfall rates and wind speeds.

Bracing for the Polar Vortex

One term that has gotten considerably more use in the last few years is polar vortex. Like many weather terms, its strict definition is often lost in conversational use. The polar vortex is not an outbreak of cold. The polar vortex exists--at both poles--all year. When it expands during the winter, it can contribute to significantly colder temperatures further away from the poles. Think of it as the tide at the beach: It's always there, but sometimes it reaches farther.

Feeling the Wind Chill

Wind chill is the wintertime cousin of the heat index. Both tools measure the impact of a second factor on the "feels like" temperature of the air. The heat index incorporates humidity, while the wind chill accounts for the effects of wind. The idea is simple: When you're in still air, it takes longer for your body to become colder because your body heat is creating a tiny blanket of warm air around you. As winds increase, this blanket is broken up more rapidly, allowing your body to chill as if the air temperature was colder, and that "as if" temperature is the wind chill.

Dropping the "Bomb Cyclone"

This term is an excellent example of how terminology can be confusing. Most people think of a massive warm-weather storm as a cyclone, but the term refers to any sprawling storm system, regardless of temperature. In this case, the cyclone is shortened from "cyclogenesis," a word that simply means the formation (genesis) of a storm (cyclone). The word "bomb" has been added to characterize the rapid speed at which certain storms come together, so we end up with the term "bomb cyclone" for nor'easters and other fast-forming storm systems.

Advisories, Watches, Warnings...What's What?

It seems like only yesterday that we were entering the spring severe weather season and thinking about watches and warnings. Now it's time to think about them from the winter perspective. The general rules still stand; a watch means that conditions favor certain events, while a warning means that the particular event is underway. An advisory also means that the event is underway but that it is not as severe as those that earn a warning. Those definitions hold true no matter what type of specific event is on the horizon.

There's Nothing Black About Black Ice

A common winter hazard is black ice. It forms when water on roadways freezes as nighttime temperatures drop below 32 degrees Fahrenheit. This situation is often a result of the daytime melting of snow, followed by an overnight freeze. Whatever the exact circumstances, don't let the name fool you. "Black" ice is so named because it freezes in a nearly transparent form, allowing you to see the black asphalt under it. The critical thing to remember about black ice is that it can form on otherwise dry roads and that it's most likely on bridges and overpasses.

Know It All About a Snow Squall

In weather, the term squall refers to a sudden outbreak of precipitation. These events are typically brief but may feature very heavy precipitation during that short time. When temperatures are low enough, that precipitation will fall as snow, resulting in a snow squall. Snow squalls can lead to a rapid accumulation that creates hazardous driving conditions. Coupled with the resulting loss of visibility, this accumulation can lead to multi-vehicle pileups. The situation is often made worse by the surprise arrival of the squalls, which often occur repeatedly throughout the day with breaks of sunshine in between.

Sleet, Snow, and Freezing Rain

Ice storms are a result of freezing rain, but that's just one thing that can fall from the winter sky. Winter precipitation is all about a delicate balancing act between temperature, dew point, and moisture. Depending on the interaction of these three elements, precipitation can be snow, sleet, rain, freezing rain, or nothing at all. Sleet occurs when precipitation begins its descent as water, then freezes before reaching the surface, where it arrives as tiny pellets of ice. Sleet can cause treacherous driving conditions, but you should also be alert to changing forms of precipitation. Sleet often takes place on a boundary between colder and warmer air, so your sleet may quickly become rain or snow. Monitor temperatures and be prepared for what's next.

How to Weather an Ice Storm

Ice storms are among the most destructive winter weather events. They occur when warm rain falls onto cold surfaces, freezing and accumulating on trees, power lines, and roadways. Unlike snow, which is more likely to fall apart on impact, the precipitation on an ice storm just gets thicker and thicker on everything it touches. Conditions only improve when temperatures surge back above freezing or, ironically, if it gets colder and the precipitation turns into snow. An ice storm will bring down trees and, with them, utility lines like electrical and phone cables. This can quickly leave thousands without heat and communication.

The Amazing Power of Lake-Effect Snow

The Great Lakes Region of North American experiences one of the most unique weather phenomena: lake-effect snow. As cold air surges across the slightly warmer water of the lakes, moisture is drawn up and forms clouds that quickly return that moisture to the ground in the form of heavy snow. Rates of two to three inches per hour are typical, and a prolonged period of lake-effect snow can quickly pile up snowfall that can measure in feet. At the same time, areas just a couple miles away from the path of the system can be sunny with no snowfall at all. This makes it critically important to monitor local weather authorities in this part of the world.

Staying safe in changing weather requires that you keep up with current and expected weather conditions. There's no shortage of information online, on TV, and the radio, but none of it will help you if you don't understand the terminology that the meteorologist uses.

The purpose of this guide is to educate you about common weather terms so that when you hear a meteorologist using them, you'll know what steps will be necessary to keep your home and family safe.

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