Sleet - Precipitation consisting of transparent pellets of ice, 5 millimeters or less in diameter. Snow Shower - A short duration of light to moderate snowfall. No measurable accumulation of snow occurs. Snow Flurries - Intermittent snowfall of short duration. Snow Advisory - Issued when snowfall is expected to exceed 2 inches but not expected to exceed 5 inches. Snowflake - White ice crystals that have combined in a complex branched hexagonal form.
Snow - Precipitation composed of white or translucent ice crystals, through direct phase change of water vapor to ice. Ice Storm Warning - Issued when damaging accumulations of ice-at least ½”- are expected during a freezing rain event. Ice Fog - Fog composed of ice crystals instead of water droplets. Ice Crystals – According to the Glossary Of Meteorology, 2 nd Edition, “any one of a number of macroscopic, crystalline forms in which ice appears, including hexagonal columns, hexagonal platelets, dendritic crystals, ice needles, and combinations of these forms.” Also issued when snowfall totaling 9 inches or more in 24 hours or less is expected. Heavy Snow Warning – In northern New England, issued when snowfall totaling 7 inches or more in 12 hours or less is expected. One additional heating degree day occurs for each degree the daily mean temperature is less than 65° F. It may be indexed to any temperature the most common is 65° F. Heating Degree Day – An parameter used to estimate the required energy for heating. Air temperatures are usually in the mid 30s Fahrenheit at eye level.įrost Point - When the temperature to which air must be cooled to saturation is below freezing.įrozen Dew – Dew that changes into tiny beads of ice when the temperature of the surface on which it formed drops to or below the freezing point. Large amounts can pull down power lines and tree branches.įrost - A covering of ice that forms on exposed surfaces when the air temperature falls below the frost point.įrost Advisory - Issued during the growing season when widespread frost formation is expected over an extensive area. Even in small amounts, freezing rain can cause traveling problems. Even in small amounts, freezing drizzle may cause traveling problems.įreezing Rain - Rain that falls in liquid form and then freezes upon impact with the ground or an item with a temperature of 32 degrees Fahrenheit or less.
However, even small amounts of freezing rain or freezing drizzle may cause traveling problems.įreezing Drizzle - Drizzle that falls in liquid form and then freezes upon impact with the ground or an item with a temperature of 32 degrees Fahrenheit or less. If the snow is lifted more than 6 feet above the ground, it is termed ‘blowing snow’.įreeze - A condition occurring over a large area when the surface air temperature remains below 32 degrees Fahrenheit for an extended period of time.įreeze Warning - Issued during the growing season when surface temperatures are expected to drop below freezing over a large area for an extended period of time, regardless if frost develops or not.įreezing Drizzle/Rain Advisory - When freezing rain or freezing drizzle is forecast but a significant amount of it is not expected. Drifting snow may occur during or after a snowfall. There are no temperature criteria in the definition of a blizzard but freezing temperatures and 35 mph winds will create sub-zero wind chills.īlowing Snow Advisory – Issued when widespread blowing snow with winds 25 to 35 mph (40 to 56 km/h), occasionally reducing visibility to 1/4 mile (400 m) or less, is expected.ĭrifting Snow - An uneven distribution of snowfall or existing snow caused by strong surface wind. Eye on the Sky Home > Glossary of Weather Terms Glossary of Weather Terms Weather Terms Winter & Fall // Spring & Summer // Commonly Used Winter & Fallīlizzard Warning - Sustained winds or frequent gusts of 35 mph (56 km/h) or greater, considerable falling and/or blowing snow reducing visibility frequently to 1/4 mile (0.4 km) or less for a period of three hours or more.
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