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How to Read Aviation Weather Charts

Aviation weather charts provide crucial information for pilots. Pilots use them to plan flights around expected weather conditions, select a departure time that will have decent weather conditions, avoid areas of bad weather and discover what to expect at altitude. In most cases, pilots flight plan with a "weather depiction chart," a type of aviation weather chart that shows sky conditions, fronts, areas of icing, areas of instrument flight rules and areas of turbulence. This chart is a snapshot of current weather conditions.

Things You'll Need

Weather depiction chart
Aviation weather services handbook

Instructions

- 1
  Identify the fronts. Fronts are boundaries between air masses, and most adverse weather conditions occur along frontal boundaries. Weather depiction charts show fronts as long, notched lines of different colors. Warm fronts are red with round notches, cold fronts are blue with triangular notches and stationary fronts are a combination of warm and cold front symbols.
- 2
  Find areas of high and low pressure. A high pressure system appears as a large, blue "H," while a low pressure system appears as a large, red "L" and is usually attached to a front. Although there are exceptions, high pressure is typically associated with good weather, while low pressure systems are usually attached to fronts and bring bad weather.
- 3
  Locate areas of icing and turbulence, which are hazardous to flying. The symbol for icing is a large "U" with vertical lines running through it. One line is for light icing, two lines for moderate icing and three lines for severe icing. Turbulence is depicted as an upside-down "V" that is stacked based on the severity of the turbulence. One "V" is for light turbulence, two "Vs" are for moderate turbulence and three "Vs" stand for severe turbulence.
- 4
  Look up the plotted data. The weather depiction chart shows plotted data for each airport, showing sky condition (clear, partly cloudy or overcast), wind strength and direction, temperature and areas of marginal visual flight rules (visibility is 3 to 5 miles, ceilings are 1,000 to 3,000 feet above ground level) instrument flight and low instrument flight rules (ceilings are less than 500 feet, visibility is less than 1 mile). Weather depiction charts have a legend that shows you how to decipher the data. To practice, find your local airport and look up the plotted symbols.
  
  (Note to CE: weather depiction charts show areas of visual and instrument flight rules. It's kind of hard to explain to someone with no aviation background, but instrument flight rules is when visibility is less than 3 miles and ceilings are less than 1000' feet above ground level. Anyone with ANY experience in aviation (even a pre-solo student pilot) will know the meaning of VFR and IFR. Still, I added an explanation into the intro for IFR. VFR is defined as "not IFR.")

Aviation