Understanding weather terms, Your Local Weather Authority’s glossary

Confused by some weather terms we use? This glossary can help!

Coming to Terms with the Weather

ROANOKE, Va. – There are many weather terms that have caught you be surprised in recent years. To help make things easier for you, here’s what they mean:

Fear not, we’ll be adding more terms, but we published this now to get a head start.

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Barometer: A weather instrument that measures air pressure.

Blizzard: A winter storm that’s accompanied by falling/blowing snow, sustained wind of at least 35 mph and visibility of 0.25 miles or less for at least three consecutive hours.

Bombogenesis/”bomb cyclone”: When the pressure in the center of a storm system drops at least 24 millibars in 24 hours. Implies a rapidly intensifying storm.



Derecho: A widespread storm that produces damaging straight-line winds. Damage must occur consistently, or intermittently along a path length of at least 400 miles and path width of at least 60 miles.


Enhanced Fujita Scale: A scale that grades the intensity of a tornado, based on the amount of damage and the structure damaged. It goes from EF-0 (weaker) to EF-5 (violent).


Front: A boundary between two air masses. This can separate cold from warm, wet from dry or humid from less humid (or all three).

Funnel Cloud: A rotating column of air that has yet to make contact with the ground.



Heat index: A measure of how the air feels when factoring the air temperature and humidity levels.

High pressure: A type of weather system that results in sinking air. Typically associated with more sunshine, drier air and pleasant days.



Jet Stream: An area of intense wind around airplane level. This separates cold air to the north from warm air to the south. This is also a region where storm systems typically develop.



Low pressure: A type of weather system that results in rising air. Typically associated with more clouds, wind and precipitation.



Nor’Easter: A type of storm that typically forms along the East Coast of the United States. Winds over the coastal region come in from the northeast.



Polar Vortex: Semi-permanent area of low pressure (24,000 to 180,000 feet in altitude) located in or near the Arctic. Pieces of this can break off, resulting in bitter cold in the eastern half of the U.S.




Saharan Dust: A plume of dust that moves east to west from the Sahara Desert. Enters the tropical Atlantic at least 3-5 times per season. Creates beautiful sunrises/sunsets, reduces odds of tropical systems but can produce poor air quality depending on the amount.


Tornado: A violently rotating column of air that comes into contact with the ground. Different from a funnel cloud.




Warning: A hazardous type of weather is likely or already happening.

Watch: A hazardous type of weather is possible. Can be issued more than a day in advance in winter weather, flooding, wind or heat.

Wind Chill: A measure of how the air feels when factoring cold air and gusty wind.




Is there a term we use that’s not on the list? Shoot me an email at cmichaels@wsls.com and I’ll add it!

About the Author

Meteorologist Chris Michaels is an American Meteorological Society (AMS) Certified Broadcaster, forecasting weather conditions in southwest Virginia on WSLS 10 News from 5 a.m. to 7 a.m. weekdays on Virginia Today.

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