AIM
4/20/23
7
−
1
−
70
Meteorology
(e) Obstructions to visibility.
There are eight types of obscuration phenomena in the METAR code
(obscurations are any phenomena in the atmosphere, other than precipitation, that reduce horizontal visibility):
FG
fog (vsby less than
5
/
8
mile)
. . . . . . . . . .
HZ
haze
. . . . . . . . . .
FU
smoke
. . . . . . . . . .
PY
spray
. . . . . . . . . .
BR
mist (vsby
5
/
8
−
6 miles)
. . . . . . . . . .
SA
sand
. . . . . . . . . .
DU
dust
. . . . . . . . . .
VA
volcanic ash
. . . . . . . . . .
NOTE
−
Fog (FG) is observed or forecast only when the visibility is less than five
−
eighths of mile, otherwise mist (BR) is observed
or forecast.
(f) Other.
There are five categories of other weather phenomena which are reported when they occur:
SQ
squall
. . . . . . . . . . .
SS
sandstorm
. . . . . . . . . . .
DS
duststorm
. . . . . . . . . . .
PO
dust/sand whirls
. . . . . . . . . .
FC
funnel cloud
. . . . . . . . . . .
+FC
tornado/waterspout
. . . . . . . . .
Examples:
TSRA
thunderstorm with moderate rain
. . . . . . . . .
+SN
heavy snow
. . . . . . . . . .
−
RA FG
light rain and fog
. . . . . . .
BRHZ
mist and haze (visibility
5
/
8
mile or greater)
. . . . . . . .
FZDZ
freezing drizzle
. . . . . . . . .
VCSH
rain shower in the vicinity
. . . . . . . .
+SHRASNPL
heavy rain showers, snow, ice pellets (intensity indicator refers to the predominant rain)
. .
9. Sky Condition.
The sky condition as reported in METAR represents a significant change from the way
sky condition is currently reported. In METAR, sky condition is reported in the format:
Amount/Height/(Type) or Indefinite Ceiling/Height
(a) Amount.
The amount of sky cover is reported in eighths of sky cover, using the contractions:
SKC
clear (no clouds)
. . . . . . . . .
FEW
>
0 to
2
/
8
. . . . . . . .
SCT
scattered (
3
/
8s
to
4
/
8s
of clouds)
. . . . . . . . .
BKN
broken (
5
/
8s
to
7
/
8s
of clouds)
. . . . . . . . .
OVC
overcast (
8
/
8s
clouds)
. . . . . . . . .
CB
Cumulonimbus when present
. . . . . . . . . .
TCU
Towering cumulus when present
. . . . . . . . .
NOTE
−
1.
“SKC” will be reported at manual stations. “CLR” will be used at automated stations when no clouds below 12,000 feet
are reported.
2.
A
ceiling layer is not designated in the METAR code. For aviation purposes, the ceiling is the lowest broken or overcast
layer, or vertical visibility into an obscuration. Also there is no provision for reporting thin layers in the METAR code. When
clouds are thin, that layer must be reported as if it were opaque.
(b) Height.
Cloud bases are reported with three digits in hundreds of feet above ground level (AGL).
(Clouds above 12,000 feet cannot be reported by an automated station).