National Weather Service weather thresholds (e.g. conditions change from visual meteorological conditions to instrument meteorological conditions). The basic weather elements observed are: sky condition, visibility, present weather, obstructions to vision, pressure, temperature, dew point, wind direction and speed, precipitation accumulation, and selected significant remarks. The coded observations are issued as METARs and look similar to this: Getting more information on the atmosphere, more frequently, and from more locations is the key to improving forecasts and warnings. Due to the large installation and operating costs associated with ASOS, the stations are widely spaced. Therefore, the Cooperative Observer Program (COOP), a network of approximately 11,000
Significant weather advisory 58 miles per hour. The product is mainly used by forecast offices located in the National Weather Service's Southern Region Headquarters. A significant weather advisory or warning is not an official National Weather Service product, instead it is issued within a special weather statement. Special weather statements are also used for any type of weather approaching watch/warning/advisory levels. Many NWS offices do not use significant weather advisories, instead issue normal special weather statements mentioning much of the same text used in such an advisory. If severe weather is detected, alerts (mainly a severe thunderstorm or tornado warning) are issued by