KEY TO DECODE AN ASOS (METAR) OBSERVATION
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METAR KABC 121755Z AUTO 21016G24KT 180V240 1SM R11/P6000FT
-RA BR BKN015 OVC025 06/04 A2990 RMK AO2 PK WND 20032/25 WSHFT 1715 VIS
3/4V1 1/2 VIS 3/4 RWY11 RAB07 CIG 013V017 CIG 017 RWY11 PRESFR SLP125
P0003 60009 T00640036 10066 21012 58033 TSNO $
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TYPE OF REPORT
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METAR: hourly (scheduled) report; SPECI: special (unscheduled)
report.
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METAR
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STATION IDENTIFIER
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Four alphabetic characters; ICAO location identifier.
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KABC
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DATE/TIME
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All dates and times in UTC using a 24-hour clock; two-digit date and
four-digit time; always appended with Z to indicate UTC.
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121755Z
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REPORT MODIFIER
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Fully automated report, no human intervention; removed when observer
signed-on.
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AUTO
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WIND DIRECTION AND SPEED
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Direction in tens of degrees from true north (first three digits); next
two digits: speed in whole knots; as needed Gusts (character)
followed by maximum observed speed; always appended with KT to
indicate knots; 00000KT for calm; if direction varies by 60° or more
a Variable wind direction group is reported.
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21016G24KT
180V240
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VISIBILITY
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Prevailing visibility in statute miles and fractions (space between
whole miles and fractions); always appended with SM to indicate
statute miles; values <1/4 reported as M1/4.
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1SM
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RUNWAY VISUAL RANGE
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10-minute RVR value in hundreds of feet; reported if prevailing
visibility is £
one mile or RVR
£
6000 feet; always appended with FT to indicate feet; value
prefixed with M or P to indicate value is lower or higher
than the reportable RVR value.
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R11/P6000FT
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WEATHER PHENOMENA
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RA: liquid precipitation that does not freeze; SN: frozen precipitation
other than hail; UP: precipitation of unknown type; intensity prefixed
to precipitation: light (-), moderate (no sign), heavy (+); FG: fog;
FZFG: freezing fog (temperature below 0°C); BR: mist; HZ: haze; SQ:
squall; maximum of three groups reported; augmented by observer: FC
(funnel cloud/tornado/waterspout); TS (thunderstorm); GR (hail); GS
(small hail; <1/4 inch); FZRA (intensity; freezing rain); VA
(volcanic ash).
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-RA BR
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SKY CONDITION
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Cloud amount and height: CLR (no clouds detected below 12000 feet);
FEW (few); SCT (scattered); BKN (broken); OVC (overcast); followed by
3-digit height in hundreds of feet; or vertical visibility (VV)
followed by height for indefinite ceiling.
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BKN015 OVC025
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TEMPERATURE/DEW POINT
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Each is reported in whole degrees Celsius using two digits; values are
separated by a solidus; sub-zero values are prefixed with an M
(minus).
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06/04
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ALTIMETER
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Altimeter always prefixed with an A indicating inches of mercury;
reported using four digits: tens, units, tenths, and hundredths.
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A2990
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REMARKS IDENTIFIER: RMK
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RMK
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TORNADIC ACTIVITY: Augmented; report should
include TORNADO, FUNNEL CLOUD, or WATERSPOUT, time begin/end, location,
movement; e.g.
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TORNADO B25 N MOV E.
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TYPE OF AUTOMATED STATION: AO2; automated
station with precipitation discriminator.
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AO2
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PEAK WIND: PK WND dddff(f)/(hh)mm; direction
in tens of degrees, speed in whole knots, and time.
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PK WND 20032/25
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WIND SHIFT: WSHFT (hh)mm
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WSHFT 1715
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TOWER OR SURFACE VISIBILITY: TWR VIS vvvvv:
visibility reported by tower personnel, e.g., TWR VIS 2; SFC VIS vvvvv:
visibility reported by ASOS, e.g.
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SFC VIS 2
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VARIABLE PREVAILING VISIBILITY: VIS
vnvnvnvnvnVv
xvxvxvxvx; reported
if prevailing visibility is < 3 miles and variable.
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VIS 3/4V1 1/2
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VISIBILITY AT SECOND LOCATION: VIS vvvvv
[LOC]; reported if different than the reported prevailing visibility in
body of report.
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VIS 3/4 RWY11
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LIGHTNING: [FREQ] LTG [LOC]; when detected
the frequency and location is reported, e.g.
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FRQ LTG NE.
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BEGINNING AND ENDING OF PRECIPITATION AND THUNDERSTORMS:
w'w'B(hh)mmE(hh)mm; TSB(hh)mmE(hh)mm
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RAB07
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VIRGA: Augmented; precipitation not reaching
the ground, e.g.
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VIRGA
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VARIABLE CEILING HEIGHT: CIG hn
hnhnVhxhxhx;
reported if ceiling in body of report is < 3000 feet and variable.
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CIG 013V017
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CEILING HEIGHT AT SECOND LOCATION: CIG hhh
[LOC]; Ceiling height reported if secondary ceilometer site is different
than the ceiling height in the body of the report.
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CIG 017 RWY11
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PRESSURE RISING OR FALLING RAPIDLY: PRESRR or
PRESFR; pressure rising or falling rapidly at time of observation.
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PRESFR
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SEA-LEVEL PRESSURE: SLPppp; tens, units,
and tenths of SLP in hPa.
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SLP125
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HOURLY PRECIPITATION AMOUNT: Prrrr; in .01
inches since last METAR; a trace is P0000.
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P0003
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3- AND 6-HOUR PRECIPITATION AMOUNT: 6RRRR;
precipitation amount in .01 inches for past 6 hours reported in 00, 06,
12, and 18 UTC observations and for past 3 hours in 03, 09, 15, and 21
UTC observations; a trace is 60000.
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60009
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24-HOUR PRECIPITATION AMOUNT: 7R24
R24R24R24; precipitation amount in .01
inches for past 24 hours reported in 12 UTC observation.
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70015
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HOURLY TEMPERATURE AND DEW POINT: Tsn
TaTaTasnT'a
T'aT'a; tenth of degree Celsius; sn:
1 if temperature below 0°C and 0 if temperature 0°C or higher.
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T00640036
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6-HOUR MAXIMUM TEMPERATURE: 1sn
TxTxTx; tenth of degree Celsius; 00,
06, 12, 18 UTC; sn: 1 if temperature below 0°C and 0 if
temperature 0°C or higher.
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10066
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6-HOUR MINIMUM TEMPERATURE: 2sn
TnTnTn; tenth of degree Celsius; 00,
06, 12, 18 UTC; sn: 1 if temperature below 0°C and 0 if
temperature 0°C or higher.
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21012
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24-HOUR MAXIMUM AND MINIMUM TEMPERATURE:
4snTxTxTxsn
TnTnTn; tenth of degree Celsius;
reported at midnight local standard time; 1 if temperature below
0°C and 0 if temperature 0°C or higher, e.g.
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400461006
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PRESSURE TENDENCY: 5appp; the character
(a) and change in pressure (ppp; tenths of hPa) the past 3 hours.
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58033
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SENSOR STATUS INDICATORS: RVRNO: RVR
missing; PWINO: precipitation identifier information not available;
PNO: precipitation amount not available; FZRANO: freezing rain
information not available; TSNO: thunderstorm information not available;
VISNO [LOC]: visibility at secondary location not available, e.g.,
VISNO RWY06; CHINO [LOC]: (cloud-height-indicator) sky condition at
secondary location not available, e.g., CHINO RWY06.
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TSNO
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MAINTENANCE CHECK INDICATOR: Maintenance
needed on the system.
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$
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If an element or phenomena does not occur, is missing, or cannot be
observed, the corresponding group and space are omitted (body and/or
remarks) from that particular report, except for Sea-Level Pressure
(SLPppp). SLPNO shall be reported in a METAR when the SLP is not
available.
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