restricted to three reportable layers except when CB or
TCU are present, in which case a fourth layer may be
used.
SURFACE-BASED OBSCURATIONS.—
Surface-based obscurations will also use NSNSNShShShS
group. However, hShShS will be encoded as 000 for
heights of less than 50 feet. Stations overseas will
encode 000 as ///.
When the sky is totally obscured, the VVhshshs
group is used in place of the NsNsNshshshs group, with
Wthe indicator for an indefinite ceiling, and hShShS the
vertical visibility into the ceiling.
CAVOK STATEMENT.—In many countries, a
statement for Ceiling And Visibility O.K. (CAVOK)
may be substituted for the visibility, weather, and sky
coverage when (1) the visibility is 10 km or greater, (2)
there are no clouds below 5,000 feet (1,500 m) and no
CB clouds, and (3) there is no significant weather
occurring. This statement is NOT acceptable for use by
Navy and Marine Corps activities.
Temperature
The temperature and dew-point temperature group
T'T'/T'dT'd is always included in a METAR observation
report. T'T' is the temperature rounded up to the nearest
whole degree Celsius, while T'dT'd is the dew-point
temperature rounded up to the nearest whole degree
Celsius. Prefix single-digit temperatures with a zero.
Negative temperatures are preceded by an M. For
example, -9°C is encoded M09. If the temperature is not
available, omit the entire group. If only the dew point is
not available, use a single solidus after the temperature
(10/).
REMARKS (RMK)
Element
METAR
SPECI
Volcanic Eruptions
X
X
Tornadic Activity
X
X
Type of Station
X
X
Peak Wind
X
Wind Shift, FROPA
X
X
Tower Visibility
X
X
Variable
Prevailing
X
X
Visibility
Sector Visibility
X
X
Lightning
X
X
Beginning/Ending
o f
X
X
Thunderstorms
and/or
Precipitation
Thunderstorm Location
X
X
Hailstone Size
X
X
Virga
X
X
Variable Ceiling
X
X
Obscuration(s)
X
X
Variable Sky Condition
X
X
Significant Cloud Types
X
X
Pressure Rising/Falling
X
X
Rapidly
Sea Level Pressure
X
X
Aircraft Mishap
X
X
No SPECI Taken
X
Snow Increasing Rapidly
X
Runway Condition
X
X
Breaks or Thin Spots in
X
X
Overcast
First and Last Remark
X
X
X
indicates
element
included at all stations
Altimeter Setting
The altimeter setting group APHPHPHPH is always
included in a METAR observation report. The altimeter
setting following the A indicator is reported in inches of
mercury rounded to the nearest hundredth of an inch.
Do not use a decimal point. For example, an altimeter
setting of 29.242 inches is encoded A2924.
REMARKS AND ADDITIVE DATA
In addition to the regularly reported data identified
in table 3-1, the METAR code may also contain many
remarks. Some of the remarks are required at different
scheduled observation times, while others are required
to provide amplification for certain significant
meteorological events. Some remarks may be in the
format of coded data groups (known as additive data
groups and supplemental data groups), or as
abbreviated plain language. NAVMETOCCOMINST
3141.2 and NAVMETOCCOMINST 3144.1 provide
general guidance for plain language remarks and the
proper abbreviations to use. FAA Order 7340.1,
Contractions, contains a word-to-contraction encoding
and contraction-to-word decoding listing for all
allowable contractions. See table 3-3 for a listing of
reportable remarks.
Table 3-3.—METAR and SPECI Code Remarks
3-9
