dddff(f)Gfmfm(fm)KT and dndndnVdXdXdX. The first
wind data group includes reported true wind direction,
wind speed, and wind character; the second group is
used to report variable wind direction. While the wind
direction and speed must be included in every METAR
report even when the wind is calm, the wind character
and wind direction variability are only reported when
WIND SPEED, DIRECTION, AND CHAR-
ACTER.dddffGfmfmKT. The true wind direction,
ddd, is reported to the nearest 10 degrees, and may be
encoded as VRB when wind speed is less than 6 knots.
For example: Wind from 90° is reported "090." The ff is
the 2-minute average wind speed in knots. If no gusts
are reported, the identifier KT follows without a space.
Calm winds are encoded "00000KT." Wind speeds
exceeding 99 knots are reported in three figures. Gusts
are only reported if winds exceed the average wind
speed by 10 knots or greater. The G is the indicator for
wind gusts, and fmfm is the maximum gust speed
observed during the last 10-minute period. Gusts
exceeding 99 knots are also reported in three figures; for
example, a wind from 270 at 25 knots with gusts to 40
knots would be encoded as 27025G40KT.
While KT is the indicator for wind speed (in knots)
as used in the United States, wind speeds may be
reported by other countries in kilometers per hour or in
meters per second.
KMH indicates wind speed in
kilometers per hour, and MPS indicates wind speed in
meters per second.
VARIABLE WIND DIRECTION GROUP.
dndndnVdxdxdx. The variable wind direction group is
only reported if the winds vary by 60° or more and the
winds are >6 knots. The dndndn is the "left" direction
limit (in true [T] azimuth degrees), while the V is an
indicator for "variable," and dxdxdx is the "right" limit.
For example, if the winds are variable between 123°T
and 191°T, the group would be encoded 120V190.
Wind direction may also be reported as variable if the
wind speed is less than 6 knots, for example,
T h e v i s i b i l i t y g r o u p s , V V V V V S M ,
R DR DR / VR VR VR VR F T , o r R DR DR
/VNVNVNVNVVXVXVXVXFT are used to report
horizontal surface visibility and runway visual range,
HORIZONTAL SURFACE VISIBILITY.
VVVVVSM group is the minimum significant surface
horizontal visibility and is reported by VVVVV in statute
miles (SM) with reportable increments, as described in
chapter 1. This element is reported in meters by
R U N W A Y V I S U A L R A N G E .
R DR DR / VR VR VR VR F T o r R DR DR /
VNVNVNVNVVXVXVXVXFT. Runway visual range
(RVR) is only reported when the RVR on any active
runway is 6,000 feet or less or the visibility is less than 1
mile. Groups may be repeated as required for each
runway. The R is the indicator for RVR, while DRDR is
the runway identifier, plus designator L (left), C
(center), or R (right) as appropriate. The VRVRVRVR is
the average touchdown RVR during the 10-minute
observation period, in hundreds of feet.
If the Runway visual range is variable, the second
RVR group, RDRDR/VNVNVNVNVVXVXVXVXFT,
is used in place of the first. To be considered variable, 1-
minute average readings must differ by more than
50 meters or, more than 20% of the mean value during
the 10-minute observation period. The lowest
reportable 1-minute mean minimum and the highest
reportable 1-minute mean maximum visual ranges,
respectively, are reported during variable RVR
When an observed RVR is less than the RVR
sensors established accurate minimum reading, the
minimum accurate reading is reported and preceded by
the letter M. Example: The sensor reports a 40-meter
visibility but the sensors minimum limit is 50 meters;
VRVRVRVR is encoded M0050FT. Likewise, if the
observed RVR is greater than the established accurate
RVR-sensor maximum, then the sensors accurate
maximum reading is reported and preceded by the letter
P. Again, OCONUS stations will report RVR using
Present Weather Groups
This group is used to report present weatherw'w'.
This group is only reported when significant weather is
occurring at the station or in the vicinity (within 10
miles of the station) at the time of the observation.
The aviation present weather group may be used
three times to include all significant weather. Each
usage consists of from two to nine characters to describe
present weather. Each group may contain, in order, an
intensity symbol "+" for heavy or "-" for light (no
intensity symbol means the precipitation is moderate)
or the indicator VC for vicinity, a two-letter qualifier