Chapter 24, Observations 24-9
Figure 24-2. ICAO Continental Codes
24.4.3.3 Date and Time of Report
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 date and time are coded in all reports as follows: the day of the month is the first two digits ( 01),
followed by the hour (19), and the minutes (55).
The coded time of observations is the actual time of the report or when the criteria for a SPECI is met or
noted.
If the report is a correction to a previously disseminated report, the time of the corrected report is the same
time used in the report being corrected.
The date and time group always ends with a Z, indicating Zulu time (or Coordinated Universal Time
(UTC)).
For example, METAR KOKC 011955Z would be disseminated as the 2,000-hour routine report for station
KOKC, taken on the 1st of the month at 1955 UTC.
24.4.3.4 Report Modifier (as appropriate)
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 report modifier AUTO identifies the METAR/SPECI as a fully automated report with no human
intervention or oversight. In the event of a corrected METAR or SPECI, the report modifier “COR” is
substituted for “AUTO.”
Chapter 24, Observations 24-10
24.4.3.5 Wind 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
Wind is the horizontal motion of air past a given point. It is measured in terms of velocity, which is a vector
that includes direction and speed. It indicates the direction the wind is coming from.
In the wind group, the wind direction is coded as the first three digits (220) and is determined by averaging
the recorded wind direction over a two-minute period. It is coded in tens of degrees relative to true north
using three figures. Directions less than 100 degrees are preceded with a 0. For example, a wind direction
of 90° is coded as 090. A wind from the north is coded as 360.
Immediately following the wind direction is the wind speed coded in two or three digits ( 15). Wind speed
is determined by averaging the speed over a two-minute period and is coded in whole knots using the units,
tens digits, and, when appropriate, the hundreds digit. When wind speeds are less than 10 kt, a leading 0 is
used to maintain at least a two-digit wind code. For example, a wind speed of 8 kt will be coded 08KT. The
wind group is always coded with a KT to indicate wind speeds are reported in knots. Other countries may
use km/h or meters per second (m/s) instead of knots.
Examples:
05008KT Wind 50° at 8 kt
15014KT Wind 150° at 14 kt
340112KT Wind 340° at 112 kt
24.4.3.5.1 Wind Gust
Wind speed data for the most recent 10 minutes is examined to evaluate the occurrence of gusts. Gusts are
defined as rapid fluctuations in wind speed with a variation of 10 kt or more between peaks and lulls. The
coded speed of the gust is the maximum instantaneous wind speed.
Wind gusts are coded in two or three digits immediately following the wind speed. Wind gusts are coded
in whole knots using the units, tens, and, when appropriate, the hundreds digit. For example, a wind out of
the west at 20 kt with gusts to 35 kt would be coded 27020G35KT.
24.4.3.5.2 Variable Wind Direction (speed 6 kt or less)
Wind direction may be considered variable when, during the previous two-minute evaluation period, the
wind speed was 6 kt or less. In this case, the wind may be coded as VRB in place of the three -digit wind
direction. For example, if the wind speed was recorded as 3 kt, it would be coded VRB03KT.
24.4.3.5.3 Variable Wind Direction (speed greater than 6 kt)
Wind direction may also be considered variable when, during the two-minute evaluation period, it varies
by 60° or more and the speed is greater than 6 kt. In this case, a variable wind direction group immediately
follows the wind group. The directional variability is coded in a clockwise direction and consists of the
extremes of the wind directions separated by a V. For example, if the wind is variable from 180 to 240 ° at
10 kt, it would be coded 21010KT 180V240.
24.4.3.5.4 Calm Wind
When no motion of air is detected, the wind is reported as calm. A calm wind is coded as 00000KT.
Chapter 24, Observations 24-11
24.4.3.6 Visibility 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
Visibility is a measure of the opacity of the atmosphere. It is defined as the greatest horizontal distance at
which selected objects can be seen and identified , or its equivalent derived from instrumental
measurements.
Prevailing visibility is the reported visibility considered representative of recorded visibility conditions at
the manual station during the time of observation. It is the greatest distance that can be seen throughout at
least half of the horizon circle, not necessarily continuous.
Surface visibility is the prevailing visibility from the surface at manual stations or the visibility derived
from sensors at automated stations.
The visibility group is coded as the surface visibility in s tatute miles. A space is coded between whole
numbers and fractions of reportable visibility values. The visibility group ends with SM to indicate that the
visibility is in statute miles. For example, a visibility of 1½ SM is coded 1 1/2SM. Most other countries use
meters.
U.S. automated stations use an M to indicate “less than.” For example, M1/4SM means a visibility of less
than ¼ SM.
24.4.3.7 Runway Visual Range (RVR) 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 RVR is an instrument -derived value representing the horizontal distance a pilot may see down the
runway.
RVR is reported whenever the station has RVR equipment and prevailing visibility is 1 SM or less, and/or
the RVR for the designated instrument runway is 6,000 ft or less. Otherwise, the RVR group is omitted.
RVR is coded in the following format: The initial R is code for runway and is followed by the runway
number. When more than one runway is defined with the same runway number, a directional letter is coded
on the end of the runway number. Next is a solidus (/) followed by the visual range in feet , and then FT
completes the RVR report. For example, an RVR value for Runway 01L of 800 ft would be coded
R01L/0800FT. Most other countries use meters.
In the United States, RVR values are coded in increments of 100 ft up to 1,000 ft, increments of 200 ft from
1,000–3,000 ft, and increments of 500 ft from 3,000–6,000 ft. Manual RVR is not reported below 600 ft.
For U .S. airports only, the touchdown zone ’s (TDZ) RVR is reported. For U .S. airports with multiple
runways, the operating runway with the lowest touchdown RVR is reported. RVR may be reported for up
to four designated runways in other countries.
When the RVR varies by more than one reportable value, the lowest and highest values will be shown with
V between them, indicating variable conditions. For example, the 10-minute RVR for Runway 01L varying
between 600 and 1,000 ft would be coded R01L/0600V1000FT.
If RVR is less than its lowest reportable value, the visual range group is preceded by M. For example, an
RVR for Runway 01L of less than 600 ft is coded R01L/M0600FT.
If RVR is greater than its highest reportable value, the visual range group is preceded by a P. For example,
an RVR for Runway 27 of greater than 6,000 ft will be coded R27/P6000FT.
Note: The link to the RVR website is located in Appendix G.
Chapter 24, Observations 24-12
24.4.3.8 Present Weather 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
Present weather includes precipitation, obscurations, and other weather phenomena. The appropriate
notations found in Table 24-3 are used to code present weather.
Table 24-3. METAR/SPECI Notations for Reporting Present Weather1
Qualifier Weather Phenomena
Intensity or
Proximity Descriptor Precipitation Obscuration Other
1 2 3 4 5
- Light
Moderate2
+ Heavy
VC In the
Vicinity3
MI Shallow
PR Partial
BC Patches
DR Low
Drifting
BL Blowing
SH Shower(s)
TS Thunderstorms
FZ Freezing
DZ Drizzle
RA Rain
SN Snow
SG Snow
Grains
IC Ice Crystals
(Diamond
Dust)
PL Ice
Pellets
GR Hail
GS Snow Pellets
UP Unknown
Precipitation
BR Mist
FG Fog
FU Smoke
VA Volcanic
Ash
DU Widespread
Dust
SA Sand
HZ Haze
PY Spray
PO Dust/Sand
Whirls
SQ Squalls
FC Funnel
Cloud,
Tornado, or
Waterspout4
SS Sandstorm
DS Dust Storm
1. The weather groups are constructed by considering columns 1 through 5 in Table 24-3 in
sequence (i.e., intensity followed by description, followed by weather phenomena ). For
example, heavy rain shower(s) is coded as +SHRA.
2. To denote moderate intensity, no entry or symbol is used.
3. See text for vicinity definitions.
4. Tornadoes and waterspouts are coded as +FC.
Separate groups are used for each type of present weather. Each group is separated from the other by a
space. METARs/SPECIs contain no more than three present weather groups.
Chapter 24, Observations 24-13
When more than one type of present weather is reported at the same time, present weather is reported in the
following order:
• Tornadic activity (tornado, funnel cloud, or waterspout).
• Thunderstorm(s) (with and without associated precipitation).
• Present weather in order of decreasing dominance (i.e., the most dominant type reported first).
• Left to right in Table 24-3 (columns 1 through 5).
Qualifiers may be used in various combinations to describe weather phenomena. Present weather qualifiers
fall into two categories:
• Intensity or proximity, and
• Descriptors.
24.4.3.8.1 Intensity Qualifier
The intensity qualifiers are light, moderate, and heavy. They are coded with precipitation types, except ice
crystals (IC) and hail ( GR), including those associated with a thunderstorm ( TS) and those of a showery
nature ( SH). Tornadoes and waterspouts are coded as heavy ( +FC). No intensity is ascribed to the
obscurations of blowing dust (BLDU), blowing sand (BLSA), and blowing snow (BLSN). Only moderate
or heavy intensity is ascribed to sandstorm (SS) and dust storm (DS).
When more than one form of precipitation is occurring at a time, or precipitation is occurring with an
obscuration, the reported intensities are not cumulative. The reported intensity will not be greater than the
intensity for each form of precipitation. For example, -FZRAPL is light freezing rain and light ice pellets,
not light freezing rain and moderate ice pellets.
24.4.3.8.2 Proximity Qualifier
Weather phenomena occurring beyond the point of observation (between 5 –10 SM) are coded as in the
vicinity ( VC). VC can be coded in combination with thunderstorm ( TS), fog ( FG), shower(s) ( SH),
well-developed dust/sand whirls ( PO), blowing dust ( BLDU), blowing sand ( BLSA), blowing snow
(BLSN), sandstorm (SS), and dust storm (DS). Intensity qualifiers are not coded in conjunction with VC.
For example, VCFG can be decoded as meaning some form of fog is between 5 –10 SM of the point of
observation. If VCSH is coded, showers are occurring between 5–10 SM of the point of observation.
Weather phenomena occurring at the point of observation (at the station) or in the vicinity of the point of
observation are coded in the body of the report. Weather phenomena observed beyond 10 SM from the
point of observation (at the station) is not coded in the body but may be coded in the remarks section.
24.4.3.8.3 Descriptor Qualifier
Descriptors are qualifiers that further amplify weather phenomena and are used in conjunction with some
types of precipitation and obscurations. The descriptor qualifiers are shallow ( MI), partial ( PR), patches
(BC), low drifting (DR), blowing (BL), shower(s) (SH), thunderstorm (TS), and freezing (FZ).
Only one descriptor is coded for each weather phenomena group (e.g., FZDZ).
The descriptors shallow (MI), partial (PR), and patches (BC) are only coded with fog (FG) (e.g., MIFG).
Mist (BR) is not coded with any descriptor.
The descriptors low drifting ( DR) and blowing ( BL) will only be coded with dust ( DU), sand ( SA), and
snow (SN) (e.g., BLSN or DRSN). DR is coded with DU, SA, or SN for raised particles drifting less than
6 ft above the ground.
Chapter 24, Observations 24-14
When blowing snow is observed with snow falling from clouds, bot h phenomena are reported
(e.g., SN BLSN). If blowing snow is occurring and the observer cannot determine whether or not snow is
also falling, then BLSN is reported. Spray (PY) is coded only with blowing (BL).
The descriptor for showery -type precipitation ( SH) is coded only with one or more of the precipitation
qualifiers for rain (RA), snow (SN), ice pellets (PL), or hail (GR). When any type of precipitation is coded
with VC, the intensity and type of precipitation is not coded.
The descriptor for thunderstorm (TS) may be coded by itself when the thunderstorm is without associated
precipitation. A thunderstorm may also be coded with the precipitation types of rain ( RA), snow (SN), ice
pellets (PL), snow pellets (GS), or hail (GR). TS is not coded with SH.
The descriptor freezing ( FZ) is only coded in combination with fog ( FG), drizzle ( DZ), or rain ( RA)
(e.g., FZRA). FZ is not coded with SH.
24.4.3.8.4 Precipitation
Precipitation is any form of water particle, whether liquid or solid, that falls from the atmosphere and
reaches the ground. The precipitation types are drizzle (DZ), rain (RA), snow (SN), snow grains (SG), ice
crystals ( IC), ice pellets ( PL), hail ( GR), snow pellets ( GS), and unknown precipitation ( UP). UP is
reported if an automated station detects the occurrence of precipitation, but the precipitation sensor cannot
recognize the type.
Up to three types of precipitation may be coded in a single present weather group. They are coded in order
of decreasing dominance based on intensity.
24.4.3.8.5 Obscuration
Obscurations are any phenomenon in the atmosphere, other than precipitation, that reduces the horizontal
visibility in the atmosphere. The obscuration types are mist ( BR), fog ( FG), smoke ( FU), volcanic ash
(VC), widespread dust (DU), sand (SA), haze (HZ), and spray (PY). Spray (PY) is coded only as BLPY.
With the exception of volcanic ash, low drifting dust, low drifting sand, low drifting snow, shallow fog,
partial fog, and patches (of) fog, an obscuration is coded in the body of the report if the surface visibility is
less than seven miles or if the obscuration is considered operationally significant. Volcanic ash is always
reported when observed.
24.4.3.8.6 Other Weather Phenomena
Other weather phenomen on types include well -developed dust/sand whirls ( PO), sandstorms ( SS), dust
storms (DS), squalls (SQ), funnel clouds (FC), and tornados and waterspouts (+FC).
Examples:
-DZ Light drizzle.
-RASN Light rain and (light) snow.
SN BR (Moderate) snow, mist.
-FZRA FG Light freezing rain, fog.
SHRA (Moderate) rain shower.
VCBLSA Blowing sand in the vicinity.
-RASN FG HZ Light rain and (light) snow, fog, haze.
TS Thunderstorm (without precipitation).
Chapter 24, Observations 24-15
+TSRA Thunderstorm, heavy rain.
+FC TSRAGR BR Tornado, thunderstorm, (moderate) rain, hail, mist.
24.4.3.9 Sky Condition 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
Sky condition is a description of the appearance of the sky. It includes cloud cover, vertical visibility, or
clear skies.
The sky condition group is based on the amount of cloud cover (the first three letters) followed by the height
of the base of the cloud cover (final three digits). No space is between the amount of cloud cover and the
height of the layer. The height of the layer is recorded in feet AGL.
Sky condition is coded in ascending order and ends at the first overcast layer. At mountain stations, if the
layer is below station level, the height of the layer will be coded with three solidi (///).
Vertical visibility is coded as VV, followed by the vertical visibility into the indefinite ceiling . An
“indefinite ceiling” is a ceiling classification applied when the reported ceiling value represents the vertical
visibility upward into surface-based obscuration. No space is between the group identifier and the ver tical
visibility. Figure 24-3 illustrates the effect of an obscuration on the vision from a descending aircraft.
The ceiling is 500 ft in both examples, but the indefinite ceiling example (bottom) produces a more
adverse impact to landing aircraft. This is because an obscuration (e.g., fog, blowing dust, snow)
limits runway acquisition due to reduced slant range visibility. This pilot would be able to see the
ground but not the runway. If the pilot was at approach minimums, the approach could not be
continued, and a missed approach would need to be executed.
Figure 24-3. Obscuration Effects on Slant Range Visibility
Chapter 24, Observations 24-16
Clear skies are coded in the format SKC or CLR. When SKC is used, an observer indicates no layers are
present; CLR is used by automated stations to indicate no layers are detected at or below 12,000 ft.
Each coded layer is separated from the others by a space. Each layer reported is coded by using the
appropriate reportable contraction seen in Table 24-4. A report of clear skies (SKC or CLR) is a complete
layer report within itself. The abbreviations FEW, SCT, BKN, and OVC will be followed (without a space)
by the height of the layer.
Table 24-4. METAR/SPECI Contractions for Sky Cover
Reportable
Contraction Meaning Summation
Amount of Layer
VV Vertical Visibility 8/8
SKC or CLR1 Clear 0
FEW2 Few 1/8 – 2/8
SCT Scattered 3/8 – 4/8
BKN Broken 5/8 – 7/8
OVC Overcast 8/8
1. The abbreviation CLR will be used at automated stations when no layers at or below 12,000 ft are
reported; the abbreviation SKC will be used at manual stations when no layers are reported.
2. Any layer amount less than 1/8 is reported as FEW.
The height is coded in hundreds of feet above the surface using three digits in accordance with Table 24-5.
Table 24-5. METAR/SPECI Increments of Reportable Values of Sky Cover Height
Range of Height Values (ft) Reportable Increment (ft)
Less than or equal to 5,000 To nearest 100
5,001 to 10,000 To nearest 500
Greater than 10,000 To nearest 1,000
The ceiling is the lowest layer aloft reported as broken or overcast. If the sky is totally obscured with
ground-based clouds, the vertical visibility is the ceiling.