Spring & Summer Terms

Apparent Temperature - See Heat Index.

Coastal Flooding - Prolonged strong onshore flow of wind and/or high astronomical tides causing a rise in sea level that floods coastal areas.

Cooling Degree Day - A form of degree day used to estimate the required energy for cooling. one cooling degree day occurs for each degree the daily mean temperature is above 65 degrees Fahrenheit.

Dew - Water that forms on objects close to the ground when its temperature falls below the dew point of the surface air.

Dew Point - The temperature of which air must be cooled for it to be saturated.

Drizzle - Precipitation in the form of liquid drops. It's diameter is less than .5 millimeters. Drizzle falls at a much slower rate than rain does.

Dry Line - A boundary which separates warm, dry air from warm, moist air. The differences in the two air masses may be significant. The dry line is usually a boundary of instability along which thunderstorms form.

Dust Devils - A small but rapidly rotating column of wind of short duration that is made visible by dust, sand, and debris picked up from the ground. Diameter usually ranges from 10 to 100 feet and develop best on clear, dry, hot afternoons. Fairly uncommon in this part of the country.

Excessive Heat Warning - Issued within 12 hours of the onset of the heat conditions listed in the excessive heat watch.

Excessive Heat Watch - Issued for the potential of the following conditions within 12 to 36 hours: heat index of at least 105 degrees Fahrenheit for more than 3 hours per day for 2 consecutive days or heat index more than 115 degrees Fahrenheit for any period of time.

Flash Flood - A flood which is caused by heavy or excessive rainfall in a short period of time, generally under 6 hours, leading to water that rises and falls quite rapidly. The term may also be used to alert the public of non life threatening flooding of small streams, streets, storm drains, and low lying urban areas. A flash flood can also be caused by the failure of a dam or from ice jams on waterways.

Flash Flood Warning - Issued to inform the public, emergency management, and other cooperating agencies that flash flooding is in progress, imminent, or highly likely.

Flash Flood Watch - Issued to indicate current or developing hydrologic conditions that are favorable for flash flooding in and close to the watch area, but the occurrence is neither certain or imminent.

Flood - The condition that occurs when water overflows the artificial or natural boundaries of a stream, river, or other body of water. Also issued for the ponding of water at or near where the rain is falling or has fallen. The term may also be used to alert the public of non life threatening flooding of small streams, streets, storm drains and low lying urban areas. It may also be used if small streams in rural areas reach or exceed bank full.

Flood Crest - Maximum height of a flood wave as it passes a certain location.

Flood Stage - The level at which a stream, river or other body of water begins to or will begin to leave its banks.

Flood Warning - Issued to inform the public, emergency management, and other cooperating agencies that flooding is in progress, imminent, or highly likely. The

Fujita Tornado Damage Scale - A scale correlating the damage from a tornado with wind speed of the tornado. View Fujita Scale.

Funnel Cloud - A rapidly rotating column of air extending from a cumulonimbus cloud with a circulation that does not reach the ground. once a funnel cloud reaches the ground it is then called a tornado.

Growing Degree Day - A form of degree day to estimate the approximate dates when a crop will be ready to harvest. one growing degree day occurs when the daily mean temperature is one degree above the minimum temperature required for the growth of that specific crop.

Hail - Precipitation in the form of transparent or partially opaque balls or irregular lumps of concentric ice. Hail is normally defined as having a diameter of 5 millimeters or more and is produced by thunderstorms.

Heat Advisory - Issued within 12 hours of the onset of the following conditions: heat index of at least 105 degrees but less than 115 degrees for less than 3 hours per day. Nighttime lows remain above 80 degrees for 2 consecutive days.  

Heat Index - (Apparent Temperature) - This index is an accurate measure of how hot it feels (in degrees) when moisture (relative humidity) is added to the actual air temperature.  View Heat Index Chart

Rain - Precipitation in the form of liquid drops the diameter of which must be .5 millimeters or greater. Implies a steady precipitation that might last for several hours.

Severe Thunderstorm - A thunderstorm with winds of 58 mph or greater and/or with hail 3/4 inches diameter or larger.

Severe Thunderstorm Warning - Issued to warn the public, emergency management and other cooperating agencies when a severe thunderstorm is forecast to occur or is occurring. The warning will include where the storm was occurring, its direction of movement and the primary threat from the storm.

Severe Thunderstorm Watch - Issued when conditions are favorable for the development of severe thunderstorms in and close to a defined area.

Shower - Intermittent rainfall of short duration that falls from a cumulus cloud. Heavy precipitation is possible. Implies more of a scattered rainfall.

Squall Line - A line of solid or nearly solid thunderstorms or strong winds that might extend for several hundred miles.

Supercell - A severe thunderstorm whose updrafts and downdrafts are in near balance allowing the storm to maintain itself for several hours. Supercells often produce large hail and tornados.

Tornado - A rapidly rotating column of air extending from a cumulonimbus cloud with a circulation that reaches the ground. However, the visible portion might not extend all the way to the ground.

Tornado Warning - Issued to warn the public, emergency management and other cooperating agencies when a tornado is forecast to occur or is occurring. The warning will include where the storm was occurring and its direction of movement.

Tornado Watch - Issued when conditions are favorable for the development of severe thunderstorms and possible tornados in and close to a defined area.

Wall Cloud - An area of clouds that extends beneath a severe thunderstorm. If a wall cloud rotates, it might precede tornado development.

Waterspout - A rapidly rotating column of air extending from a cumulonimbus cloud with a circulation that reaches the surface of the water, (i.e. a tornado over water).