Upper Air

200 mb Plot learn more

200 mb Plot

The 200 millibar (mb) map plots a variety of information collected by weather balloons and represents atmospheric conditions at an altitude of approximately 12,000 meters (39,000 feet). The map displays:
  • The air temperature (degrees Celsius) in red
  • The dew point temperature (degrees Celsius) in green
  • The height of the 200 mb level (decameters) in black. For example, "1188" means 11,880 meters.
  • Winds (knots) – The wind barb is an "arrow" that depicts the wind speed and direction. The "feathers" of the arrow indicate the wind speed while the blank end of the arrow indicates the direction the wind is blowing toward.
Also shown on the map as brown lines are contours of the height of the 200 mb level (decameters). These are at intervals of 120 meters.

This map is updated twice a day.
500 mb Plot learn more

500 mb Plot

The 500 millibar (mb) map plots a variety of information collected by weather balloons and represents atmospheric conditions at an altitude of approximately 5,500 meters (18,000 feet). The map displays:
  • The air temperature (degrees Celsius) in red
  • The dew point temperature (degrees Celsius) in green
  • The height of the 500 mb level (decameters) in black. For example, "558" means 5,580 meters.
  • Winds (knots) – The wind barb is an "arrow" that depicts the wind speed and direction. The "feathers" of the arrow indicate the wind speed while the blank end of the arrow indicates the direction the wind is blowing toward.
Also shown on the map as brown lines are contours of the height of the 500 mb level (decameters). These are at intervals of 60 meters.

This map is updated twice a day.
850 mb Plot learn more

850 mb Plot

The 850 millibar (mb) map plots a variety of information collected by weather balloons and represents atmospheric conditions at an altitude of approximately 1,500 meters (5,000 feet). The map displays:
  • The air temperature (degrees Celsius) in red
  • The dew point temperature (degrees Celsius) in green
  • The height of the 850 mb level (decameters) in black. For example, "154" means 1,540 meters.
  • Winds (knots) – The wind barb is an "arrow" that depicts the wind speed and direction. The "feathers" of the arrow indicate the wind speed while the blank end of the arrow indicates the direction the wind is blowing toward.
Also shown on the map as brown lines are contours of the height of the 850 mb level (decameters). These are at intervals of 30 meters.

This map is updated twice a day.
RUC Model Critical Thickness Plot learn more

RUC Model Critical Thickness Plot

The RUC Model Critical Thickness Plot denotes the locations of the 1000-500 mb, 1000-700 mb, and 850-700 mb critical thickness lines across the United States. Areas to the north of all of these lines indicate an atmospheric temperature profile that will most likely result in snow. Areas to the south of all of these lines indicate an atmospheric temperature profile that will most likely result in rain. Areas in between will typically have mixed precipitation (rain, sleet, and snow). This map is updated hourly.