Winds & Temperatures Aloft

Conditions at altitude can differ significantly from what pilots observe on the surface. Understanding winds and temperatures aloft forecasts helps pilots anticipate changes in groundspeed, fuel burn, and aircraft performance during climb and cruise.


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.
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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