Winds & Temperatures Aloft (FBs)

Winds and Temperatures Aloft forecasts aid pilots in determining atmospheric conditions at various altitudes for use in flight planning and performance calculations.


Winds & Temperatures Aloft

Winds & Temperatures Aloft Introduction

  • Winds and Temperatures Aloft, also called "FBs," are computer-prepared forecasts for specific locations in the contiguous U.S. and a network of locations in Alaska and Hawaii.
  • These forecasts (versus observed) aid pilots in the planning and execution of cross-country (non-local) flights by providing wind direction, wind speed, and temperatures at specified times, altitudes, and locations.

Winds & Temperatures Aloft

Winds & Temperatures Aloft Purpose

  • Various models culminate in the winds and temperature aloft forecast.
  • Pilots need to know how to read winds and temperatures aloft charts and graphics to aid in planning.
    • While cross-country flight planning and execution are primary reasons pilots look at winds and temperatures aloft, these reports can also apply to local flights.
  • Specifically, winds & temperatures aloft forecasts aid pilots in:
    • Determining the most favorable altitude based on winds and the direction of flight.
    • Provide data with which to calculate aircraft performance (fuel consumption, time of flight, etc.).
    • Identifying areas of possible aircraft icing by noting air temperature of +2°C to -20°C, and temperature inversions.
    • Predicting turbulence by observing abrupt changes in wind direction and speed at different altitudes.

Winds & Temperatures Aloft

Winds & Temperatures Aloft Issuance & Validity

  • Winds and Temperatures Aloft Forecast Stations
    Winds and Temperatures Aloft Forecast Stations
  • Winds and Temperature Aloft Forecast (FB) Periods
    Aviation Weather Handbook
    Winds and Temperature Aloft Forecast (FB) Periods

  • Winds & Temperatures Aloft Issuance:

  • Winds & Temperatures Aloft Validity:

    • Amendments are not issued to winds aloft forecasts.
      • Data can therefore be up to six hours old.
      • If the scheduled forecast is delayed, the existing valid forecast based on the earlier 6-hourly data can be used until a new forecast is transmitted.
  • Winds and Temperature Aloft Forecast (FB) Periods
    Aviation Weather Handbook
    Winds and Temperature Aloft Forecast (FB) Periods

Winds & Temperatures Aloft

Winds & Temperatures Aloft Forecast Elements

  • Textual Winds and Temperatures Aloft Forecast Example
    Textual Winds and Temperatures Aloft Forecast Example
  • GFA Displayed Winds Over California
    GFA Displayed Winds Over California
  • Aviation Weather Handbook, NWS Surface Analysis Chart Sample Wind Symbols
    Aviation Weather Handbook,
    NWS Surface Analysis Chart Sample Wind Symbols
  • GFA Displayed Temperatures Over California
    GFA Displayed Temperatures Over California
  • Pilots can locate textual reports on the Aviation Weather Center Website under the "Products"/"Wind/temp data" drop-down.
  • Textual and graphical formats are available.

  • Textual Winds & Temperatures Elements:

    • Textual Wind and Temperature Aloft forecasts consist of two elements: the header and the forecasted data chart. [Figure 3]

    • Textual FB Header:

      • "FD" indicates a wind and temperatures aloft forecast.
      • "FD1US1" is a standard line regardless of the reported region.
      • The date and time group (DTG) of data collection is listed.
        • "DATA BASED ON: 131800Z:" Data is presented based on the 13th day of the month, 1800Z.
      • Valid at the "FOR USE" times listed.
        • "FOR USE: 2000-0300Z:" for use between 2000Z and 0300Z.
      • "TEMPS NEG ABOVE 24000" is a standard line.
        • Since temperatures above 24,000' are always negative, reports omit the negative ("-") sign.
    • Textual Winds and Temperatures Aloft Forecast Example
      Textual Winds and Temperatures Aloft Forecast Example

    • Textual FB Forecasted Data (body):

      • Winds & temperature forecast data for 3000, 6000, 9000, 1200, 18000, 24,000, 30000, 34,000, and 39000 feet.
        • Hawaii and the Western Pacific data include winds for 1,000, 1,500, and 2,000-foot altitudes.
      • "FT" indicates the levels of the wind and temperature data.
      • A four-digit group shows wind direction in tens of degrees, and the second two are wind speed in knots.
      • Altitude data up to and including 15,000 feet are true altitudes (references to MSL).
      • Altitude data at or above 18,000 feet are pressure altitudes (references to FL).
      • The symbolic form of the forecasts is DDff+TT, in which:
        • DD is the wind direction (True North).
        • ff the wind speed (knots).
        • TT the temperature (Celsius).
      • Forecasted Winds Aloft:
        • No winds forecasted within 1,500' AGL of station elevation.
        • Forecasted winds display in tens of degrees (two digits) from True North with wind speed in knots (two digits).
          • 2022: 200@22 knots.
        • If forecasted wind speeds are to be less than 5 knots, the wind group reads 9900, which means "light and variable."
          • 990012: winds are light and variable, temperature 12°C.
        • If forecast speed is greater than 100 knots, subtract 100 from the wind speed and add 50 to the wind direction.
          • 731960:
            • Step 1: 73-50 = 23 or 230.
            • Step 2: 19 + 100 = 119.
            • Result: 230@119 (temperature -60°C).
        • If forecasted wind speeds are to be 200 knots or greater, the wind group reads 99 knots.
          • 189960: 180@200+ (temperature -60°C).
      • Forecasted Temperatures Aloft:
        • Forecasts omit temperatures within 2,500' AGL of station elevation.
        • A six-digit group includes forecast temperatures in degrees Celsius.
          • 192832: The last two digits show 32°C for the temperature, but remember that above 24,000 feet, reports exclude the negative ("-") sign.

  • Graphical Winds & Temperatures Aloft Reports:

    • Pilots can locate graphical winds and temperatures aloft forecasts on the >Aviation Weather Center's Website under the "Weather/Winds/Temperatures" drop-down. [Figure 4]
    • The graphical chart displays various layers simultaneously or not at all.
    • An altitude chart allows the pilot to select the desired altitude for viewing forecasted data.
    • A validity bar allows the pilot to read the forecast data timeframe in the standard 6-hour increment.

    • Graphical Forecasted Winds Aloft:

      • Wind data displays with a wind flag and a "heat map." [Figure 4/5]
        • Don't misinterpret the term heat map or the color display to represent temperatures when only viewing winds.
      • Interpreting Wind Flags:
        • A point depicts stations from which a line extends.
        • The line represents the direction of the wind (i.e., follow the line down to the station for direction).
        • At the end of the line are barbs with a short line indicating 5 knots, a longer line indicating 10 knots, and a triangle indicating 50 knots.
          • Wind barbs are additive, so two long lines are 20 knots.
          • If no flag is present, winds are calm (less than 5 knots).
        • Gusts, if forecast, are written at the end of the flag with the letter G to represent gusts and the number reflecting speed in knots.
      • Interpreting Wind Speeds:
        • A heat map overlay provides wind speed data at a glance, especially over vast areas.
        • The brighter the color, the higher the wind speed.
        • Terrain displays in those mountainous areas at elevations higher than those selected by the elevation slider.
      • Clicking on the station also provides the wind direction and wind speed forecast at that station.
      • Unlike the textual report, which provides winds at 1,000, 1,500, and 2,000 feet for Hawaii and the Western Pacific, the graphical tool elevation chart does not display below 3,000 feet.
      • GFA Displayed Winds Over California
        GFA Displayed Winds Over California
      • Aviation Weather Handbook, NWS Surface Analysis Chart Sample Wind Symbols
        Aviation Weather Handbook,
        NWS Surface Analysis Chart Sample Wind Symbols
      • Graphical Forecasted Temperatures Aloft:
        • Temperature data displays with a color map (legend in the bottom right of the web tool). [Figure 6]
        • Unlike wind flags, temperature data displays with colors only per the legend.
        • GFA Displayed Temperatures Over California
          GFA Displayed Temperatures Over California

Winds & Temperatures Aloft

Winds & Temperatures Aloft Conclusion

  • The winds & temperatures aloft forecast chart provides a concise means to interpret winds across a wide span of locations and altitudes.
  • Pilots need to learn how to read wind and temperature aloft forecasts, primarily for longer-distance flight planning, but occasionally for local flights as well.
  • For more information, a paper copy of the Federal Aviation Administration (FAA-H-8083-28) Aviation Weather Handbook [Amazon] is available for purchase.
  • Textual reports provide simple, low-bandwidth solutions for pilots, while graphical reports are more interactive and intuitive, especially over wide areas.
  • Winds and temperatures aloft have long validity times for conditions that can often fluctuate.
  • Winds and temperatures are not forecasted within 1500 and 2500 feet, respectively, meaning these blocks will appear blank for some stations in mountainous areas.
  • Check out the aircraft icing and atmosphere pages to learn more about how winds and temperatures aloft is applied.
  • Improve your weather skills with FAA-provided (and WINGS-credited) resources by going to https://www.faasafety.gov/ and typing "weather" into the search bar.
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Winds & Temperatures Aloft

Winds and Temperatures Aloft References