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Weather Charts – Surface Analysis Chart

in Aviation Weather Services

The surface analysis chart depicts an analysis of the current surface weather. [Figure 12-14] This chart is a computer prepared report that is transmitted every 3 hours and covers the contiguous 48 states and adjacent areas. A surface analysis chart shows the areas of high and low pressure, fronts, temperatures, dew points, wind directions and speeds, local weather, and visual obstructions.


Figure 12-14. Surface analysis chart.

Figure 12-14. Surface analysis chart.

Surface weather observations for reporting points across the United States are also depicted on this chart. Each of these reporting points is illustrated by a station model. [Figure 12-15] A station model includes:

Figure 12-15. Sample station model and weather chart symbols.

Figure 12-15. Sample station model and weather chart symbols.

  • Type of observation—a round model indicates an official weather observer made the observation. A square model indicates the observation is from an automated station. Stations located offshore give data from ships, buoys, or offshore platforms.
  • Sky cover—the station model depicts total sky cover and is shown as clear, scattered, broken, overcast, or obscured/partially obscured.
  • Clouds—represented by specific symbols. Low cloud symbols are placed beneath the station model, while middle and high cloud symbols are placed directly above the station model. Typically, only one type of cloud will be depicted with the station model.
  • Sea level pressure—given in three digits to the nearest tenth of a millibar (mb). For 1,000 mbs or greater, prefix a 10 to the three digits. For less than 1,000 mbs, prefix a 9 to the three digits.
  • Pressure change/tendency—pressure change in tenths of mb over the past 3 hours. This is depicted directly below the sea level pressure.
  • Precipitation—a record of the precipitation that has fallen over the last 6 hours to the nearest hundredth of an inch.
  • Dew point—given in degrees Fahrenheit.
  • Present weather—over 100 different weather symbols are used to describe the current weather.
  • Temperature—given in degrees Fahrenheit.
  • Wind—true direction of wind is given by the wind pointer line, indicating the direction from which the wind is coming. A short barb is equal to 5 knots of wind, a long barb is equal to 10 knots of wind, and a pennant is equal to 50 knots.

515G+mn0RuL._SX331_BO1,204,203,200_Learn more about aviation weather with Weather Flying by Robert Buck. Regarded as the bible of weather flying, this aviation classic not only continues to make complex weather concepts understandable for even the least experienced of flyers, but has now been updated to cover new advances in technology.

 

 

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