AVIATION ROUTING WEATHER REPORT (METAR)
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Remarks Section for the METAR/
/SPECI Code
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Index
General
Remarks shall be included in all METAR and SPECI, if appropriate.
Note: The United States does not report remarks in the same manner as the WMO
standard.
Remarks shall be separated from the body of the report by a space and the
contraction RMK. If there are no remarks, the contraction RMK
is not required.
METAR/SPECI remarks fall into 2 categories:
(1) Automated, Manual, and Plain
Language, and (2) Additive and Maintenance Data.
Remarks shall be made in accordance with the following:
- Where plain language is called for, authorized contractions,
abbreviations, and symbols should be used to conserve time and space. However,
in no case should an essential remark, of which the observer is aware, be
omitted for the lack of readily available contractions. In such a case, the
only requirement is that the remark be clear.
- Time entries shall be made in minutes past the hour if the time
reported occurs during the same hour the observation is taken. Hours and
minutes shall be used if the hour is different, or this handbook prescribes the
use of the hour and minutes.
- Present weather coded in the body of the report as VC may be further
described, i.e., direction from the station, if known. Weather phenomena
beyond 10 statute miles of the point(s) of observation shall be coded as
distant (DSNT) followed by the direction from the station. For example,
precipitation of unknown intensity within 10 statute miles east of the station
would be coded as "VCSH E"; lightning 25 statute miles west of the station
would be coded as "LTG DSNT W".
- Distance remarks shall be statute miles except for automated lightning
remarks which are in nautical miles.
- Movement of clouds of weather, if known, shall be coded with respect to
the direction toward which the phenomena is moving. For example, a
thunderstorm moving toward the northeast would be coded as "TS MOV NE".
- Directions shall use the eight points of the compass coded in clockwise
order.
- Insofar as possible, remarks shall be entered in the order they are
presented in the following paragraphs.
Automated, Manual, and Plain
Language Remarks
These remarks generally elaborate on parameters reported in the body of the
report. Automated and manual remarks may be generated either by an automated
or manual station. Plain language remarks are only provided from manual
stations.
- Volcanic Eruptions (Plain Language). Volcanic eruptions shall be
coded. The remark shall be plain language and contain the following, if known:
- Name of volcano.
- Latitude and longitude or the direction and the approximate distance
from the station.
- Date/Time (UTC) of the eruption.
- Size description, approximate height, and direction of movement of the
ash cloud.
- Any other pertinent data about the eruption.
For example, a remark on a volcanic eruption would look like the following:
MT. AUGUSTINE VOLCANO 70 MILES SW ERUPTED 231505 LARGE ASH CLOUD EXTENDING TO
APRX 30000 FEET MOVING NR.
Pre-eruption volcanic activity shall not be coded. Pre-eruption refers to
unusual and/or increasing volcanic activity which could presage a volcanic
eruption.
- Funnel Cloud (Tornadic activity_B/E(hh)mm_LOC/DIR_(MOV)). At manual
stationS, tornadoes, funnel clouds, or waterspouts shall be coded in the format,
TORNADIC ACTIVITY_B/E(hh)mm_LOC/DIR_(MOV), where:
- TORNADO, FUNNEL CLOUD, or WATERSPOUT identifies the
specific tornadic activity,
- B/E denotes the beginning and/or ending time,
- (hh)mm is the time of occurrence (only the minutes are required if
the hour can be inferred from the time of the report),
- LOC/DIR is the location and/or direction of the phenomena from the
station, and
- MOV is the movement, if known, from the station.
Tornadic activity shall be coded as the first remark after the "RMK"
entry. For example, "TORNADO B13 6 NE" would indicate that a tornado,
which began at 13 minutes past the hour, was 6 statute miles northeast of the
station.
- Type of Automated Station (AO1 or AO2). AO1 or AO2
shall be coded in all METAR/SPECI from automated stations.
- AO1 - Automated stations without a precipitation discriminator.
- AO2 - Automated stations with a precipitation discriminator.
- Peak Wind (PK_WND_dddff(f)/(hh)mm). The peak wind shall be coded in
the format, PK_WND_dddff(f)/(hh)mm of the next METAR, where:
- PK_WND is the remark identifier,
- ddd is the direction of the peak wind,
- ff(f) is the peak wind speed since the last METAR, and
- (hh)mm is the time of occurrence (only the minutes are required if
the hour can be inferred from the report time).
There shall be a space between the two elements of the remark identifier and
the wind direction/speed group. A solidus "/" (without spaces) shall
separate the wind direction/speed group and the time. For example, a peak wind
of 45 knots from 280 degrees that occurred at 15 minutes past the hour would be
coded "PK WND 28045/15".
- Wind Shift (WSHFT_(hh)mm). A wind shift shall be coded in the
format WSHFT_(hh)mm, where:
- WSHFT is the remark identifier and
-
(hh)mm is the time the wind shift began (only the minutes are required
if the hour can be inferred from the report time).
The contraction FROPA may be entered following the time if it is
reasonably certain that the wind shift was the result of a frontal passage.
There shall be a space 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 after the hour would be coded as "WSHFT 30 FROPA".
- Tower or Surface Visibility (TWR_VIS_vvvvv or SFC_VIS_vvvvv). Tower
visibility or surface visibility shall be coded in the formats,
TWR_VIS_vvvvv or SFC_VIS_vvvvv, respectively, where:
- vvvvv is the observed tower/surface visibility value. A space shall
be coded between each of the remark elements. For example, the control tower
visibility of 1 1/2 statute miles would be coded "TWR VIS 1 1/2".
- Variable Prevailing Visibility (VIS_vnvn
vnvnVvxvxvx
vxvx). Variable
prevailing visibility shall be coded in the format VIS_vn
vnvnvnVvxvx
vxvxvx where:
- VIS is the remark identifier, vn
vnvnvn is the lowest visibility
evaluated,
- V denotes variability between two values, and
vxvxvxvxvx is the
highest visibility evaluated.
There shall be one space following the remark identifier; no spaces between the
letter V and the lowest/highest values. For example, a visibility that
was varying between 1/2 and 2 statute miles would be coded "VIS 1/2V2".
- Sector Visibility (VIS_[DIR]_vvvvv){Plain Language]. The sector
visibility shall be coded in the format VIS_[DIR]_vvvvv, where:
- VIS is the remark identifier,
- [DIR] defines the sector to 8 points of the compass, and
- vvvvv is the sector visibility in statute miles, using the
appropriate set of values in Table A-3.
For example, a visibility of 2 1/2 statute miles in the northeastern octant
would be coded "VIS NE 2 1/2".
- Visibility At Second Location (VIS_vvvvv_[LOC]). At designated
automated stations, the visibility at a second location shall be coded in the
format VIS_vvvvv_[LOC], where:
- VIS is the remark identifier,
- vvvvv is the measured visibility value, and
- [LOC] is the specific location of the visibility sensor(s) at the
station.
This remark shall only be generated when the condition is lower than that
contained in the body of the report. For example, a visibility of 2 1/2
statute miles measured by a second sensor located at runway 11 would be coded
"VIS 2 1/2 RWY11".
- Lightning (Frequency_LTG(type)_[LOC]).
- When lightning is observed at a manual station, the frequency,
type of lightning, and location shall be reported. The remark shall be coded
in the format Frequency_LTG(type)_[LOC]. The contractions for the type
and frequency of lightning shall be based on Table A-22. For example,
"OCNL LTGICCG OHD", "FRQ LTG VC", or "LTG DSNT W".
- When lightning is detected by an automated system:
- Within 5 nautical miles of the Airport Location Point (ALP),
it will be reported as TS in the body of the report with no remarks.
- Between 5 and 10 nautical miles of the ALP, it will be
reported as VCTS in the body of the report with no remarks.
- Beyond 10 but less than 30 nautical miles of the ALP, it
will be reported in remarks only as LTG DSNT followed by the direction from the
ALP.
Table A-22. Type and Frequency
of Lightning |
Type of Lightning |
Type |
Contraction |
Definition |
Cloud-ground |
CG |
Lightning occurring between cloud and ground. |
In-cloud |
IC |
Lightning which takes place within the cloud. |
Cloud-cloud |
CC |
Streaks of lightning reaching from one cloud
to another. |
Cloud-air |
CA |
Streaks of lightning which 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 per minute. |
Frequent |
FRQ |
About 1 to 6 flashes per minute. |
Continuous |
CONS |
More than 6 flashes per minute. |
- Beginning and Ending of Precipitation (w'w'B(hh)mmE(hh)mm). At
designated stations, the beginning and ending of precipitation shall be coded
in the format, w'w'B(hh)mmE(hh)mm, where:
- w'w' is the type of precipitation,
- B denotes the beginning,
- E denotes the ending, and
- (hh)mm is the time of occurrence (only the minutes are required if
the hour can be inferred from the report time).
There shall be no spaces between the elements. The coded
remarks are not required in SPECI and should be reported in the next
METAR.
Intensity qualifiers shall not be coded. For example, if rain began at 0005,
ended at 0030, and snow began at 0020, and ended at 0055, the remarks would be
coded "RAB05E30SNB20E55". If the precipitation were showery, the
remark would be coded "SHRABO5E30SHSNB20E55".
- Beginning and Ending of Thunderstorms (TSB(hh)mmE(hh)mm). The
beginning and ending of thunderstorm(s) shall be coded in the format,
TSB(hh)mmE(hh)mm, where:
- TS indicated thunderstorm,
- B denotes the beginning,
- E denotes the ending, and
- (hh)mm is the time of occurrence (only the minutes are required if
the hour can be inferred from the report time).
There shall be no spaces between the elements. For example, if a thunderstorm
began at 0159 and ended at 0230, the remark would be coded "TSB0159E30".
- Thunderstorm Location (TS_LOC_(MOV_DIR)) [Plain Language].
Thunderstorm(s) shall be coded in the format, TS_LOC_(MOV_DIR), where:
- TS identifies the thunderstorm activity,
- LOC is the location of the thunderstorm(s) from the station, and
- MOV_DIR is the movement with direction, if known.
For
example, a thunderstorm southeast of the station and moving toward the
northeast would be coded "TS SE MOV NE".
- Hailstone Size (GR_[size])[Plain Language]. At designated stations,
the hailstone size shall be coded in the format, GR_[size], where:
- GR is the remark identifier and
- [size] is the diameter of the largest hailstone. The
hailstone size shall be coded in 1/4 inch increments.
For example, "GR 1 3/4" would indicate that the largest hailstones were
1 3/4 inches in diameter. If GS is coded in the body of the report, no
hailstone size remark is required.
- Virga (VIRGA_(DIR)) [Plain Language]. Virga shall be coded in the
format, VIRGA_(DIR) where:
- VIRGA is the remark identifier and
- DIR is the direction from the station. The direction of the phenomena
from the station is optional, e.g., "VIRGA" or "VIRGA SW".
- Variable Ceiling Height (CIG_hnhn
hnVhxhxhx). The variable ceiling
height shall be coded in the format, CIG_hnhn
hnVhxhxhx, where:
- CIG is the remark identifier,
- hnhnhn is the lowest ceiling
height evaluated,
- V denotes variability between two values, and
- hxhxhx is the highest ceiling height
evaluated.
There shall be one space following the remark identifier; no spaces
between the letter V and the lowest/highest ceiling values. For example,
"CIG 005V010" would indicate a ceiling that was varying between 500
feet and 1,000 feet.
- Obscurations (w'w'_[NsNsNs]
hshshs) [Plain Language]. Obscurations
(surface-based or aloft) shall be coded in the format, w'w'_[Ns
NsNs]hshshs,
where:
- w'w' is the weather causing the obscuration at the surface or aloft,
-
NsNsNs, is the applicable sky cover
amount of the obscurations aloft (FEW, SCT,
BKN, OVC) or at the surface (FEW, SCT, BKN),
and
- hshshs is the applicable
height.
Surface-based obscurations shall have a height of "000". There shall
be a space separating the weather causing the obscuration and the sky cover
amount; there shall be no space between the sky cover amount and the height.
For example, fog hiding 3-4 oktas of the sky would be coded "FG SCT000";
a broken layer at 2,000 feet composed of smoke would be coded "FU BKN 020".
- Variable Sky Condition (NsNsNs
(hshshs)_V_
NsNsNs) [Plain Language]. The
variable sky condition remark shall be coded in the format,
NsNsNs
(hshshs)_V_
NsNsNs, where:
- NsNsNs
(hshshs) and
NsNsNs identifies the two
operationally significant sky conditions and V denotes the variability
between the two ranges. If there are several layers with the same sky condition amount,
the layer height (hshshs) of the
variable layer shall be coded. For example, a cloud layer at 1,400 feet that
is varying between broken and overcast would be
coded "BKN014 V OVC".
- Significant Cloud Types [Plain Language]. The significant cloud
type remark shall be coded in all reports in the folling manner:
- Cumulonimbus or Cumulonimbus Mammatus (CB or CBMAM_LOC_(MOV_DIR).
Cumulonimbus or cumulonimbus mammatus, as appropriate, (for which no
thunderstorm is being reported) shall be coded in the format,
CB or CBMAM_LOC_(MOV_DIR), where:
- CB or CBMAM is the cloud type,
- LOC is the direction from the station, and
- MOV_DIR is the movement with direction (if known).
The cloud type, location, movement, and direction entries shall be
separated from each other with a space. For example, a CB up to 10
statute miles west of the station moving toward the east would be coded
CB W MOV E. If the CB was more than 10 statute miles to the
west, the remark would be coded CB DSNT W.
- Towering Cumulus (TCU_[DIR]). Towering cumulus clouds shall be
coded in the format, TCU_[DIR], where:
-
TCU is the cloud type and
- DIR is the direction from the station.
The cloud type and direction entries shall be separated by a space. For
example, a towering cumulus cloud up to 10 statute miles west of the station
would be coded TCU W.
- Altocumulus castellanus (ACC_[DIR]). Altocumulus castellanus
shall be coded in the format, ACC_[DIR], where:
- ACC is the cloud type and
- DIR is the direction from the station.
The cloud type and direction entries shall be separated by a space. For
example, an altocumulus cloud 5 to 10 statute miles northwest of the station
would be coded ACC NW.
- Standing lenticular or Rotor clouds (CLD_[DIR]). Stratocumulus
(SCSL), altocumulus (ACSL), or cirrocumulus (CCSL), or
rotor clouds shall be
coded in the format, CLD_[DIR], where:
- CLD is the cloud type and
- DIR is the direction from the station.
The cloud type and direction entries shall be separated by a space. For
example, altocumulus standing lenticular clouds observed southwest through
west of the station would be coded ACSL SW-W; an apparent rotor cloud
5 to 10 statute miles northeast of the station would be coded APRNT ROTOR
CLD NE; and cirrocumulus clouds south of the station would be coded
CCSL S.
- Ceiling Height at Second Location (CIG_hhh_[LOC]). At designated
stations, the ceiling height at a second location shall be coded in the format,
CIG_hhh_[LOC], where:
- CIG is the remark identifier,
- hhh is the measured height of the ceiling, and
- [LOC] is the specific location of the ceilometer(s) at the
station.
This remark shall only be generated when the ceiling is lower than
that contained in the body of the report. For example, if the ceiling measured
by a second sensor located at runway 11 is broken at 200 feet, the remark would
be CIG 002 RWY 11.
- Pressure Rising or Falling Rapidly (PRESRR/PRESFR). At designated
stations, when the pressure is rising or falling rapidly at the time of the
observation, the remark PRESRR (pressure rising rapidly) or
PRESFR (pressure falling rapidly) shall be included in the report.
- Sea-Level Pressure (SLPppp). At designated stations, the sea-level
pressure shall be coded in the format SLPppp, where:
- SLP is the remark identifier and
- ppp is the tens, units, and tenths of the sea-level pressure in
hectopascals.
For example, a sea-level pressure of 998.2 hectopascals would be
coded as SLP982. For a METAR, if sea-level pressure is not
available, it is coded as .
- Aircraft Mishap (ACFT_MSHP) [Plain Language]. If a report is taken
to document weather conditions when notified of an aircraft mishap, the remark
ACFT_MSHP shall be coded in the report but not transmitted. The act of
non-transmission shall be indicated by enclosing the remark in parentheses in
the record, i.e., ACFT MSHP.
- No SPECI Reports Taken (NOSPECI) [Plain Language]. At manual stations
where SPECI's are not taken, the remark NOSPECI shall be coded to
indicate that no changes in weather conditions will be reported until the next
METAR.
- Snow Increasing Rapidly (SNINCR_[inches-hour/inches on ground]). At
designated stations, the snow increasing rapidly remark shall be reported, in
the next METAR, whenever the snow depth increases by 1 inch or more in
the past hour. The remark shall be coded in the format,
SNINCR_[inches-hour/inches on ground], where:
- SNINCR is the remark indicator,
- inches-hour is the depth
increase in the past hour, and
- inches on ground is the total depth of snow on
the ground at the time of the report.
The depth increase in the past hour and the total depth on the ground are
separated from each other by a solidus /.
For example, a snow depth increase of 2 inches in the past hour with a total
depth on the ground of 10 inches would be coded SNINCR2/10.
- Other Significant Information [Plain Language]. Agencies may add to
a report other information significant to their operations, such as information
on fog dispersal operations, runway conditions, FIRST or LAST
report from station, etc.
Additive Coded and Automated
Maintenance Data
Additive data groups are only reported at designated stations. The maintenance
data groups are only reported from automated stations.
- Precipitation
- Amount of Precipitation. The amount of liquid precipitation shall
be coded as the depth of precipitation that accumulates in an exposed vessel
during the time period being evaluated. The amount of freezing or frozen
precipitation shall be the water equivalent of the solid precipitation
accumulated during the appropriate time period.
- Units of Measure for Precipitation. Precipitation measurements
shall be in inches, tenths of inches, or hundredths of inches depending on the
precipitation being measured. See Table A-23.
Table A-23. Units of Measure of
Precipitation |
Type of Measurement |
Unit of Measure |
Liquid Precipitation |
0.01 inch |
Water Equivalent of Solid Precipitation |
0.01 inch |
Solid Precipitation |
0.1 inch |
Snow Precipitation |
1.0 inch |
- Depth of Freezing or Frozen Precipitation. The depth of freezing
and/or frozen precipitation shall be the actual vertical depth of the
precipitation accumulated on a horizontal surface during the appropriate time
period. If snow falls, melts, and refreezes, the depth of ice formed shall be
included in the measurement.
- Hourly Precipitation Amount (Prrrr). At designated
automated stations, the hourly precipitation amount shall be coded in the
format, Prrrr, where:
- P is the group indicator and
- rrrr is the water equivalent of all precipitation that has occurred
since the last METAR (METAR, not a SPECI).
The amount shall be coded in hundredths of an inch. For example, P0009
would indicate 9/100 of an inch of precipitation fell in the past hour;
P0000 would indicate that less than 1/100 of an inch of precipitation
(considered a trace) fell in the past hour.
This group is omitted if no precipitation occurred since the
last METAR.
- 3- and 6-hour Precipitation (6RRRR). At designated
stations, the 3- and 6-hourly precipitation group shall be coded in the format
6RRRR, where:
- 6 is the group indicator and
- RRRR is the amount of precipitation.
The amount of precipitation (water equivalent) accumulated in the past 3 hours
shall be reported in the 3-hourly report; the amount accumulated in the past 6
hours shall be reported in the 6-hourly report. The amount of precipitation
shall be coded in inches, using the tens, units, tenths and hundredths digits
of the amount. When an indeterminable amount of precipitation has occurred
during the period, 6RRRR shall be coded . For example,
2.17 inches of precipitation would be coded 60217. A trace shall be
coded 60000.
- 24-Hour Precipitation Amount (7R24R24
R24R24). At
designated stations, the 24-hour precipitation amount shall be coded in the
format, 7R24R24R24R24, where:
- 7 is the group indicator and
- R24R24R24R24 is the
24-hour precipitation amount.
The 24-hour precipitation amount shall be included in the 1200 UTC (or other
agency designated time) report whenever more than a trace of precipitation
(water equivalent) has fallen in the preceding 24 hours. The amount of
precipitation shall be coded by using the tens, units, tenths, and hundredths
of inches (water equivalent) for the 24-hour period. If more than a trace
(water equivalent) has occurred and the amount cannot be determined, the group
shall be coded 7////. For example, 1.25 inches of precipitation
(water equivalent) in the past 24 hours shall be coded 70125.
- Snow Depth on Ground (4/sss). At designated stations, the
total snow depth on the ground group shall be coded in the 0000 and 1200 UTC
observation whenever there is more than a trace of snow on the ground. It
shall be coded in the 0600 and 1800 UTC observation if there is more than a
trace of snow on the ground and more than a trace of precipitation (water
equivalent) has occurred within the past 6 hours. The remark shall be coded in
the format 4/sss, where:
- 4/ is the group indicator and
- sss is the snow depth in whole inches using three digits.
For example, a snow depth of 21 inches shall be coded as 4/021.
- Water Equivalent of Snow on Ground (933RRR). At designated
stations, the water equivalent of snow on the ground shall be coded each day,
in the 1800 UTC report, if the average snow depth is 2 inches or more. The
remark shall be coded in the format, 933RRR, where:
- 933 is the group indicator and
- RRR is the water equivalent of snow, i.e., snow, snow pellets,
snow grains, ice pellets, ice crystals, and hail, on the ground.
The water equivalent shall be coded in tens, units, and tenths of inches,
using three digits. If the water equivalent of consists entirely of hail, the
group shall not be coded. A water equivalent of 3.6 inches from snow would be
coded as 933036; a water equivalent of 12.5 would be coded as 933125.
- Cloud Types (8/CLCMCH). At
designated stations, the group, 8/CLCMCH,
shall be reported and coded in 3- and 6-hourly reports when clouds are
observed.
- The predominant low cloud (CL),
middle cloud (CM), and high cloud
(CH), shall be identified in accordance with the
WMO International Cloud Atlas, Volumes I and II, or the WMO Abridged
International Cloud Atlas or agency observing aids for cloud identification.
- A 0 shall be coded for the low, middle, or high cloud type if no
cloud is present in that classification.
- A solidus "/" shall be coded for layers above an overcast.
- If no clouds are observed due to clear skies, the
cloud type group shall not be coded.
For example, a report of 8/6// would indicate an overcast layer of
stratus clouds; a report of 8/903 would indicate cumulonimbus type
low cloud, no middle clouds, and dense cirrus high clouds.
- Duration of Sunshine (98mmm). At sunshine duration reporting sites,
the duration of sunshine that occurred the previous calendar day shall be coded
in the 0800 UTC report. If the station is closed at 0800 UTC, the group shall
be coded in the first 6-hourly METAR after the station opens. The
duration of sunshine shall be coded in the format, 98mmm, where:
- 98 is the group indicator and
- mmm is the total minutes of sunshine.
The minutes of sunshine shall be coded using the hundreds, tens, and units
digits. For examples, 96 minutes of sunshine would be coded 98096.
If no sunshine occurred, the group would be coded 98000.
- Hourly Temperature and Dew Point
(TsnT'T'T'snT'dT'dT'd).
At designated stations, the hourly temperature and dew point group shall be
coded to the tenth of a degree Celsius in the format,
TsnT'T'T'snT'dT'dT'd
where:
- T is the group indicator,
- sn is the sign of the temperature,
- T'T'T' is the temperature, and
- T'dT'dT'd is the dew point.
The sign of the temperature and dew point
shall be coded as 1 if the value is below 0oC and 0
if the value is 0oC or higher. The temperature and dew point shall
be reported in tens, units, and tenths of degree Celsius. There shall be no
spaces between the entries. For example, a temperature of 2.6oC
and dew point of -1.5oC would be reported in
the body of the report as 03/M01 and the
TsnT'T'T'snT'dT'dT'd
group as
T00261015. If dew point is missing, report the temperature; if the
temperature is missing, do not report the temperature/dew point group.
- 6-Hourly Maximum Temperature (1snTx
TxTx). At designated stations, the
6-hourly maximum temperature group shall be coded in the format,
1snTx
TxTx, where:
- 1 is the group indicator,
- sn is the sign of the temperature,
- TxTxTx is
the maximum temperature in tenths of degrees Celsius using three digits.
The sign of the maximum temperature shall be coded as 1 if the maximum
temperature is below 0oC and 0 if the maximum temperature is
0oC or higher. For example, a maximum temperature of
-2.1oC would be coded 11021; 14.2oC would be
coded 10142.
- 6-Hourly Minimum Temperature (2snTn
TnTn). At designated stations, the
6-hourly minimum temperature group shall be coded in the format,
2snTnTnTn,
where:
- 2 is the group indicator,
- sn is the sign of the temperature,
- TnTnTn is
the minimum temperature in tenths of degrees Celsius using three digits.
The sign of the minimum temperature shall be coded as 1 if the minimum
temperature is below 0oC and 0 if the minimum temperature is
0oC or higher. For example, a
minimum temperature of -0.1oC would be coded 21001;
1.2oC would be coded 20012.
- 24-hour Maximum and Minimum Temperature (4sn
TxTxTxsnTn
TnTn). At
designated stations, the 24-hour maximum temperature and the 24-hour minimum
temperature shall be coded in the format,
4snTxTxTxsn
TnTnTn, where:
- 4 is the group indicator,
- sn is the sign of the temperature,
- TxTxTx is the maximum
24-hour temperature, and
- TnTnTn is the 24-hour minimum
temperature.
TxTxTx and
TnTnTn shall be coded in tenths of
degrees Celsius using three digits. The sign of the maximum or minimum
temperature shall be coded as 1 if it is below
0oC and 0 if it is 0oC or higher. For example, a
24-hour maximum temperature of 10oC and a 24-hour minimum
temperature of -1.5oC would be coded 401001015;
a 24-hour maximum temperature of 11.2oC and a 24-hour minimum
temperature of 8.4oC would be coded as 401120084.
- 3-Hourly Pressure Tendency (5appp). At designated stations, the
3-hourly pressure tendency group shall be coded in the format, 5appp,
where:
- 5 is the group indicator,
- a is the character of pressure change over the past 3
hours and
- ppp is the amount of barometric change in tenths of hectopascals.
See table A-24.
The amount of barometric change shall be coded using the tens,
units, and tenths digits. For example, a steady increase of 3.2 hectopascals
in the past three hours would be coded 52032.
Table A-24. Characteristics of
Barometer Tendency |
Primary Requirement |
Description |
Code Figure |
Atmospheric pressure now higher
than 3 hours ago. |
Increasing, then decreasing |
0 |
Increasing, then then steady, or increasing then
increasing more slowly. |
1 |
Increasing steadily or unsteadily. |
2 |
Decreasing or steady, then increasing; or
increasing, then increasing more rapidly. |
3 |
Atmospheric pressure now same as
3 hours ago. |
Increasing, then decreasing |
0 |
Steady |
4 |
Decreasing, then increasing. |
5 |
Atmospheric pressure now lower
than 3 hours ago. |
Decreasing, then increasing. |
5 |
Decreasing then steady; or decreasing then
decreasing more slowly. |
6 |
Decreasing steadily or unsteadily. |
7 |
Steady or increasing, then decreasing; or
decreasing then decreasing moe rapidly. |
8 |
- Sensor Status Indicators. Sensor status indicators should be
reported as indicated below:
- If the Runway Visual Range should not be reported but is missing,
RVRNO shall be coded.
- When automated stations are equipped with a present weather identifier and
that sensor is not operating, the remark PWINO shall be coded.
- When automated stations are equipped with a tipping bucket rain
gauge and that sensor is not operating, PNO shall be coded.
- When automated stations are equipped when a freezing rain sensor
and that sensor is not operating, the remark FZRANO shall be coded.
- When automated stations are equipped with a lightning detection
system and that sensor is not operating, the remark TSNO shall be coded.
- When automated stations are equipped with a secondary visibility
sensor that sensor is not operating, the remark VISNO_LOC shall be coded.
- When automated stations are equipped with a secondary ceiling
height indicator and that sensor is not operating, the remark
CHINO_LOC shall be coded.
- Maintenance Indicator. A maintenance indicator sign, $,
shall be coded when an automated system detects that maintenance is needed on
the system.
The following shows examples of U.S. METAR formatted observation.
METAR KOXC 231155Z AUTO 34003KT 10SM BKN036 OVC042 17/13 A2994 RMK A01=
PKMJ 231155Z 00000KT 15SM FEW015TCU SCT050 BKN300 27/24 A2985 RMK TCU VC E
SLP110 60003 70015 8/801 T02720241 10290 20256 50002=
KTBN 231155Z 34004KT 2 1/2SM BR BKN002 BKN100 OVC250 21/20 A3007 RMK SLP172
70009 8/671 9/521 5////=
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