Winter Weather Terms You Should Know
With winter weather in full swing in many areas of Canada, it's a good idea to brush up on some of the winter weather terms we may have either forgotten or wish we could forget.
Arctic Outflow- this warning is issued when any combination of wind speed and temperature giving a wind chill of -20 or lower for 6 hours or more. A separate Wind Warning is not required.
Blizzard- a blizzard warning is issued when winds of 40 km/h or greater are expected to cause widespread reductions in visibility to 400 metres or less, due to blowing snow, or blowing snow in combination with falling snow, for at least 4 hours.
Freezing Rain- rain that freezes on contact with the ground or solid objects.
Frost- a deposit of small white ice crystals formed on the ground or other surfaces when the temperature falls below freezing.
Flash Freeze- when significant ice is expected to form on roads, sidewalks or other surfaces over much of a region because of the freezing of residual water from either melted snow or falling/fallen rain due to a rapid drop in temperatures.
Graupel- is precipitation that forms when supercooled water droplets are collected and freeze on falling snowflakes, forming 2–5 mm balls of rime.
Ice Pellets- are a type of solid precipitation that has a diameter of less than 5mm. They are spherical or irregular and rarely conical. Ice pellets form when snowflakes start to melt as they fall from the cloud, then fall through sub-freezing air where they re-freeze into grain-like particles.
Nor’easter - is a macro-scale extratropical cyclone in the western North Atlantic Ocean. The name derives from the direction of the winds that blow from the northeast.
Polar Vortex- is an upper-level low-pressure area lying near one of the Earth's poles. There are two polar vortices in the Earth's atmosphere, overlying the North and South Poles.
Snowsquall- a sudden moderately heavy snowfall with blowing snow and strong, gusty surface winds. It is often referred to as a whiteout and is similar to a blizzard but is localized in time or in location and snow accumulations may or may not be significant.