Page 37 - AFMAN 15-111, 12 MAR 2019

AFMAN15-111 12 MARCH 2019 37

7.4.1. Wind direction is determined by averaging the direction the wind is coming from with
regards to true north, over a 2-minute period. Wind direction is reported using a 3-digit
compass heading rounded to the nearest 10 degrees, or when meeting criteria below, may be
reported as variable (VRB). Note: At OCONUS locations where the host nation is responsible
for the airfield observation, winds may be reported using a different standard (i.e. 10-minute
average instead of 2-minute).
7.4.2. Wind Speed is determined by averaging the speed over a 2-minute period and is reported
in whole knots.
7.4.3. Wind gusts are determined by evaluating the most recent 10-minutes of wind speed data
for rapid fluctuation in speed with a variation of 10 knots or more between peaks and lulls. The
speed of a gust shall be the maximum instantaneous wind speed.
7.4.4. Peak Wind Speed is the highest instantaneous wind speed measured within the
aerodrome during the specified reporting period. The hourly peak wind data is only reported
in the remarks of a METAR when the speed is greater than 25 knots; see Attachment 3 for
remark format. The daily peak wind data is reported in the summary of the day regardless of
speed. For incomplete wind records, data may still be used if it is determined by the weather
technician that the peak wind speed occurred outside the period of missing data; otherwise,
treat the element as missing.
7.4.5. Wind Shifts are a change in direction by at least 45 degrees that occurs in less than 15
minutes and has sustained winds of at least 10kts throughout the shift. See Attachment 3 for
remark format.

Table 7.1. Wind Observing Standards.