Chapter 24, Observations 24-17
Clouds at 1,200 ft obscure 2/8 of the sky (FEW). Higher clouds at 3,000 ft obscure an additional 1/8 of the
sky, and because the observer cannot see above the 1,200-ft layer, they are to assume that the higher 3,000-ft
layer also exists above the lower layer (SCT). The highest clouds at 5,000 ft obscure 2/8 of the sky, and ,
again, since the observer cannot see past the 1,200 and 3,000 -ft layers, they are to assume the higher
5,000-ft layer also exists above the lower layers (BKN). The sky condition group wo uld be coded
as: FEW012 SCT030 BKN050.
Figure 24-4. METAR/SPECI Sky Condition Coding
At manual stations, cumulonimbus ( CB) or towering cumulus ( TCU) is appended to the associated layer.
For example, a scattered layer of towering cumulus at 1,500 ft would be coded SCT015TCU and would be
followed by a space if there were additional higher layers to code.
Examples:
SKC No layers are present.
CLR No layers are detected at or below 12,000 ft AGL.
FEW004 Few at 400 ft AGL.
SCT023TCU Scattered layer of towering cumulus at 2,300 ft AGL.
BKN100 Broken layer (ceiling) at 10,000 ft AGL.
OVC250 Overcast layer (ceiling) at 25,000 ft AGL.
VV001 Indefinite ceiling with a vertical visibility of 100 ft AGL.
FEW012 SCT046 Few clouds at 1,200 ft, scattered layer at 4,600 ft AGL.
SCT033 BKN085 Scattered layer at 3,300 ft, broken layer (ceiling) at 8,500 ft AGL.
Chapter 24, Observations 24-18
SCT018 OVC032CB Scattered layer at 1,800 ft AGL, overcast layer (ceiling) of cumulonimbus
at 3,200 ft AGL.
SCT009 SCT024 BKN048 Scattered layer at 900 ft AGL, scattered layer at 2,400 ft AGL, broken layer
(ceiling) at 4,800 ft AGL.
24.4.3.10 Temperature/Dewpoint Group
METAR KOKC 011955Z AUTO 22015G25KT 180V250 3/4SM R17L/2600FT +TSRA BR OVC010CB
18/16 A2992 RMK AO2 TSB25 TS OHD MOV E SLP132
Temperature is the degree of hotness or coldness of the ambient air, as measured by a suitable instrument.
Dewpoint is the temperature to which a given parcel of air must be cooled at constant pressure and constant
water vapor content for the air to become fully saturated.
Temperature and dewpoint are coded as two digits rounded to the nearest whole degree Celsius. For
example, a temperature of 0.3°C would be coded at 00. Sub-zero temperatures and dewpoints are prefixed
with an M. For example, a temperature of 4 °C with a dewpoint of -2°C would be coded as 04/M02; a
temperature of -2°C would be coded as M02.
If temperature is not available, the entire temperature/dewpoint group is not coded. If dewpoint is not
available, temperature is coded followed by a solidus (/) and no entry is made for dewpoint. For example,
a temperature of 1.5°C and a missing dewpoint would be coded as 02/.
24.4.3.11 Altimeter Group
METAR KOKC 011955Z AUTO 22015G25KT 180V250 3/4SM R17L/2600FT +TSRA BR OVC010CB
18/16 A2992 RMK AO2 TSB25 TS OHD MOV E SLP132
The altimeter setting group codes the current pressure at elevation. This setting is then used by aircraft
altimeters to determine the true altitude above a fixed plane of MSL.
The altimeter group always starts with an A and is followed by the four-digit group representing the pressure
in tens, units, tenths, and hundredths of inches of mercury. The decimal point is not coded. For example,
an altimeter setting of 29.92 inHg would be coded as A2992.
24.4.3.12 Remarks (RMK)
METAR KOKC 011955Z AUTO 22015G25KT 180V250 3/4SM R17L/2600FT +TSRA BR OVC010CB
18/16 A2992 RMK AO2 TSB25 TS OHD MOV E SLP132
Remarks are included in METAR and SPECI, when appropriate.
Remarks are separated from the body of the report by the contraction RMK. When no remarks are
necessary, the contraction RMK is not used.
METAR/SPECI remarks fall into two categories (see Table 24-6):
• Automated, Manual, and Plain Language; and
• Additive and Automated Maintenance Data.
Chapter 24, Observations 24-19
Table 24-6. METAR/SPECI Order of Remarks
Automated, Manual, and Plain Language Additive and Automated
Maintenance Data
1. Volcanic Eruptions 14. Hailstone Size 27. Precipitation Amount Within a
Specified Time Period*
2. Funnel Cloud 15. Virga 28. Cloud Types*
3. Type of Automated
Station 16. Variable Ceiling Height 29. Duration of Sunshine*
4. Peak Wind 17. Obscurations 30. Hourly Temperature and Dewpoint
5. Wind Shift 18. Variable Sky Condition 31. 6-Hourly Maximum Temperature*
6. Tower or Surface
Visibility 19. Significant Cloud Types 32. 6-Hourly Minimum Temperature*
7. Variable Prevailing
Visibility 20. Ceiling Height at Second
Location 33. 24-Hour Maximum and Minimum
Temperature*
8. Sector Visibility 21. Pressure Rising or Falling
Rapidly 34. 3-Hourly Pressure Tendency*
9. Visibility at Second
Location 22. Sea Level Pressure 35. Sensor Status Indicators
10. Lightning 23. Aircraft Mishap 36. Maintenance Indicator
11. Beginning and Ending of
Precipitation 24. No SPECI Reports Taken NOTE: Additive data is primarily used by
the NWS for climatological purposes.
*These groups should have no direct impact
on the aviation community and will not be
discussed in this document.
12. Beginning and Ending of
Thunderstorms 25. Snow Increasing Rapidly
13. Thunderstorm Location 26. Other Significant
Information
Remarks are made in accordance with the following:
• Time entries are made in minutes past the hour if the time reported occurs during the same hour the
observation is taken. Hours and minutes are used if the hour is different.
• Present weather coded in the body of the report as VC may be further described (e.g., direction
from the station, if known). Weather phenomena beyond 10 SM of the point(s) of observation are
coded as distant (DSNT) followed by the direction from the station. For example, precipitation of
unknown intensity within 10 SM east of the station would be coded as VCSH E; lightning 25 SM
west of the station would be coded as LTG DSNT W.
• Distance remarks are in statute miles, except for automated lightning remarks, which are in nautical
miles.
• Movement of clouds or weather, when known, is coded with respect to the direction toward which
the phenomena are moving. For example, a thunderstorm moving toward the northeast would be
coded as TS MOV NE.
Chapter 24, Observations 24-20
• Directions use the eight points of the compass coded in a clockwise order.
• Insofar as possible, remarks are entered in the order they are presented in the following sections
(and Table 24-6).
24.4.3.13 Automated, Manual, and Plain Language Remarks
These remarks generally elaborate on parameters reported in the body of the report. An automated station
or observer may generate automated and manual remarks. Only an observer can provide plain language
remarks.
24.4.3.13.1 Volcanic Eruptions
Volcanic eruptions are coded in plain language and contain the following, when known:
• Name of volcano;
• Latitude and longitude, or the direction and approximate distance from the station;
• Date/time (UTC) of the eruption;
• Size description, approximate height, and direction of movement of the ash cloud; and
• Any other pertinent data about the eruption.
For example, a remark on a volcanic eruption would look like the following:
RMK MT. AUGUSTINE VOLCANO 70 MILES SW ERUPTED AT 231505 LARGE ASH CLOUD EXTENDING
TO APRX 30000 FEET MOVING NE.
Pre-eruption volcanic activity is not coded. Pre -eruption refers to unusual and/or increasing volcanic
activity that could presage a volcanic eruption.
24.4.3.13.2 Funnel Cloud
At manual or augmented stations, when a certified weather observer is on duty , tornadoes, funnel clouds,
and waterspouts are coded in the following format: tornadic activity; followed by TORNADO, FUNNEL
CLOUD, WATERSPOUT, or DUST/SAND WHIRL (DUST DEVIL); followed by the beginning and/or
ending time; followed by the location and/or direction of the phenomena from the station, and/or movement,
when known. For example, TORNADO B13 6 NE would indicate that a tornado began at 13 minutes past
the hour and was 6 SM northeast of the station.
24.4.3.13.3 Type of Automated Station
AO1 or AO2 is coded in all METAR s/SPECIs from automated stations. Automated stations without a
precipitation discriminator are identified as AO1; automated stations with a precipitation discriminator are
identified as AO2.
24.4.3.13.4 Peak Wind
Peak wind is coded in the following format: the remark identifier PK WND, followed by the direction of
the wind (first three digits), peak wind speed (next two or three digits) since the last METAR, and the time
of occurrence. A space is between the two elements of the remark identifier and the wind direction/speed
group; a solidus (/), without spaces, separates the wind direction/speed group and the time. For example, a
peak wind of 45 kt from 280° that occurred at 15 minutes past the hour is coded PK WND 28045/15.
Chapter 24, Observations 24-21
24.4.3.13.5 Wind Shift
Wind shift is coded in the following format: the remark identifier WSHFT, followed by the time the wind
shift began. The contraction FROPA is entered following the time if there is reasonable data to consider
the wind shift was the result of a frontal passage. A space is between the remark identifier and the time and,
if applicable, between the time and the frontal passage contraction. For example, a remark reporting a wind
shift accompanied by a frontal passage that began at 30 minutes past the hour would be coded
WSHFT 30 FROPA.
24.4.3.13.6 Tower or Surface Visibility
Tower or surface visibility is coded in the following format: tower (TWR VIS) or surface (SFC), followed
by the observed tower/surface visibility value. A space is coded between each of the remark elements. For
example, the control tower visibility of 1½ SM would be coded TWR VIS 1 1/2.
24.4.3.13.7 Variable Prevailing Visibility
Variable prevailing visibility is coded in the following format: the remark identifier VIS, followed by the
lowest and highest visibilities evaluated, separated by the letter V. A space follows the remark identifier ,
and no spaces are between the letter V and the lowest/highest values. For example, a visibility that was
varying between ½ and 2 SM would be coded VIS 1/2V2.
24.4.3.13.8 Sector Visibility
Sector visibility is coded at manual stations in the following format: the remark identifier VIS, followed by
the sector referenced to eight points of the compass, and the sector visibility in statute miles. For example,
a visibility of 2½ SM in the northeastern octant is coded VIS NE 2 1/2.
24.4.3.13.9 Visibility at Second Location
At designated automated stations, the visibility at a second location is coded in the following format: the
remark identifier VIS, followed by the measured visibility value and the specific location of the visibility
sensor(s) at the station. This remark will only be generated when the condition is lower than that contained
in the body of the report. For example, a visibility of 2½ SM measured by a second sensor located at
Runway 11 is coded VIS 2 1/2 RWY11.
24.4.3.13.10 Lightning
When lightning is observed at a manual station, the frequency, type of lightn ing, and location are
reported. The contractions for the type and frequency of li ghtning are based on Table 24-7
(e.g., OCNL LTGICCG NW, FRQ LTG VC, or LTG DSNT W).
When lightning is detected by an automated system:
• Within 5 NM of the Airport Location Point (ALP), it is reported as TS in the body of the report
with no remark.
• Between 5 –10 NM of the ALP, it is reported as VCTS in the body of the report with no remark.
• Beyond 10 NM but less than 30 NM of the ALP, it is reported in remarks only as LTG DSNT,
followed by the direction from the ALP.
Chapter 24, Observations 24-22
Table 24-7. METAR/SPECI Type and Frequency of Lightning
Type of Lightning
Type Contraction Definition
Cloud-Ground CG Lightning occurring between cloud and ground.
In-Cloud IC Lightning that takes place within the cloud.
Cloud-Cloud CC Streaks of lightning reaching from one cloud to another.
Cloud-Air CA Streaks of lightning that pass from a cloud to the air but do
not strike the ground.
Frequency of Lightning
Frequency Contraction Definition
Occasional OCNL Less than 1 flash/minute.
Frequent FRQ About 1 to 6 flashes/minute.
Continuous CONS More than 6 flashes/minute.
24.4.3.13.11 Beginning and Ending of Precipitation
At designated stations, the beginning and ending times of precipitation are coded in the following format:
the type of precipitation, followed by either a B for beginning or an E for ending, and the time of occurrence.
No spaces are coded between the elements. The coded times of the precipitation start and stop times are
found in the remarks section of the next METAR. The times are not required to be in the SPECI. The
intensity qualifiers are coded. For example, if rain began at 0005 and ended at 0030, and then snow began
at 0020 and ended at 0055, the remark would be coded RAB05E30SNB20E55. If the precipitation was
showery, the remark is coded SHRAB05E30SHSNB20E55. If rain ended and snow began at 0042, the
remark would be coded as RAESNB42.
24.4.3.13.12 Beginning and Ending of Thunderstorms
The beginning and ending times of thunderstorms are coded in the following format: the thunderstorm
identifier TS, followed by either a B for beginning or an E for ending, and the time of occurrence. No
spaces are between the elements. For example, if a thunderstorm began at 0159 and ended at 0230, the
remark is coded TSB0159E30.
24.4.3.13.13 Thunderstorm Location
Thunderstorm locations are coded in the following format: the thunderstorm identifier TS, followed by the
location of the thunderstorm(s) from the station, and the direction of movement, when known. For example,
a thunderstorm southeast of the station and moving toward the northeast is coded TS SE MOV NE.
Chapter 24, Observations 24-23
24.4.3.13.14 Hailstone Size
At designated stations, the hailstone size is coded in the following format: the hail identifier GR, followed
by the size of the largest hailstone. The hailstone size is coded in ¼ in increments. For example, GR 1 3/4
would indicate that the largest hailstones were 1¾ in in diameter. When small hail with a size less than ¼ in
is occurring, the hailstone size is reported in the remarks as GR LESS THAN 1⁄4 in.
24.4.3.13.15 Virga
At designated stations, virga is coded in the following format: the identifier VIRGA, followed by the
direction from the station. The direction of the phenomena from the station is optional (e.g., VIRGA or
VIRGA SW).
24.4.3.13.16 Variable Ceiling Height
The variable ceiling height is coded in the following format: the identifier CIG, followed by the lowest
ceiling height recorded, V denoting variability between two values, and ending with the highest ceiling
height. A single space follows the identifier with no other spaces between the letter V and the lowest/highest
ceiling values. For example, CIG 005V010 would indicate a ceiling is variable between 500–1,000 ft.
24.4.3.13.17 Obscurations
Obscurations, surface-based or aloft, are coded in the following format: the weather identifier causing the
obscuration at the surface or aloft, followed by the sky cover of the obscuration aloft ( FEW, SCT, BKN,
OVC) or at the surface ( FEW, SCT, BKN), and the height. Surface -based obscurations have a height
of 000. A space separates the weather causing the obscuration and the sky cover; no space is between the
sky cover and the height. For example, fog hiding 3/8 to 4/8 of the sky is coded FG SCT000; a broken
layer at 2,000 ft composed of smoke is coded FU BKN020.
24.4.3.13.18 Variable Sky Condition
Variable sky condition remarks are coded in the following format: the two operationally significant sky
conditions (FEW, SCT, BKN, and OVC), separated by spaces, and V denoting the variability between the
two ranges. If several layers have the same condition amount, the layer height of the variable layer is coded.
For example, a cloud layer at 1,400 ft varying between broken and overcast is coded BKN014 V OVC.
24.4.3.13.19 Significant Cloud Types
At manual stations, significant cloud type remarks are coded in all reports.
24.4.3.13.19.1 Cumulonimbus
Cumulonimbus not associated with thunderstorms is coded as CB, followed by the direction from the
station, and the direction of movement, when known. The location, direction, and direction of movement
entries are separated from each other by a space. For example, a cumulonimbus up to 10 SM west of the
station moving toward the east would be coded CB W MOV E. If the cumulonimbus was more than 10 SM
to the west, the remark is coded CB DSNT W.
24.4.3.13.19.2 Towering Cumulus
Towering cumulus clouds are coded in the following format: the identifier TCU, followed by the direction
from the station. The cloud type and direction entries are separated by a space. For example, a towering
cumulus cloud up to 10 SM west of the station is coded TCU W.