Radar Summary Chart

• Solid lines enclose precipitation areas
• Symbols specify the forums and types of precipitation
• A mix is indicated by the use of two pertinent symbols separated by a slash
• Areas of continuous precipitation is shaded as well as precipitation covering more than half of the area
• A bold dashed line is used to separate precipitation with contrasting characteristics
• A dashed line would be used to separate an area of similar characteristics (snow and rain)

Weather Flying Categories:

Ceiling and visibility determine the category

VFR: Visual Flight Rules:

• VFR areas are those areas not enclosed by either dashed or solid lines

MVFR: Marginal Visual Flight Rules:

• MVFR areas are enclosed by dashed lines

IFR: Instrument Flight Rules:

• IFR areas are enclosed by solid lines

Freezing Levels:

• Freezing levels are depicted by a zigzag line labeled as "SFC"
• Freezing levels aloft are depicted by thin, short dashed lines
• Lines are drawn at 4,000 ft intervals (80 = 8,000 ft)
• Lines are discontinued where they intersect corresponding altitudes of the Rocky Mountains
• Areas with multiple freezing levels have lines drawn to the highest freezing level

Turbulence:

• Areas of moderate or greater turbulence are enclosed by bold, long dashed lines
• Turbulence intensities are identified by symbols
• The vertical extend of turbulence layers are specified by top and base heights
• Areas of thunderstorms do not include indications of turbulence because it is implied
• Added emphasis is included if the turbulence is form the surface to above 24,000' having thunderstorms covering more than half of the area
• Intensity symbols and layer altitudes appear within or adjacent to the forecast areas

Conclusion:

• A clear radar display (no echoes) does not mean that there is no significant weather within the coverage of the radar site
  • Clouds and fog are not detected by the radar
  • However, when echoes are present, turbulence can be implied by the intensity of the precipitation, and icing is implied by the presence of the precipitation at temperatures at or below zero degrees Celsius
  • Used in conjunction with other weather products, radar provides invaluable information for weather avoidance and flight planning
  • A digital copy of Advisory Circular (00-45), Aviation Weather Services is available from the FAA's website

  References:

  • Federal Aviation Administration (FAA-H-8083-28) Aviation Weather Handbook
  • Federal Aviation Administration - Pilot/Controller Glossary
  • Advisory Circular (00-45) Aviation Weather Services
  • Aviation Weather.gov - Radar Summary Chart
  • CFI Notebook.net - Atmosphere