ATS/ESS 452: Synoptic Meteorology
Friday “Lab” 08/29/2014
- METAR
- The Station Model
What is a METAR?
• Acronym for METeorological Aviation Report
• Generated at least once an hour (usually right
prior to the end) or when a significant change
in weather occurs
• Composed of two parts: Body and Remarks
• Information contained within is added in a
specific order and format
Example
KHSV 121553Z 22010KT 3SM -RA BR OVC010 09/08 A2969 RMK AO2 RAB01E11B45 CIG
007V012 SLP053 P0000 T00940078
• Information ALWAYS given includes:
• Station ID
• Date/Time
• Wind Speed/Direction
• Visibility
• Current Observed Weather
• Sky conditions
• Temperature/Dewpoint
• Altimeter Reading (Pressure)
• Any information given after RMK are referred to as remarks, and this information can vary
Web Resources
Station ID Look-up:
http://www.nws.noaa.gov/tg/siteloc.shtml
Federal Meteorological Handbook Chapter on
METAR:
http://www.ofcm.gov/fmh-1/pdf/L-CH12.pdf
Station ID
• Example = KABC
• 4 character identifier for reporting stations
• The first letter identifies the country. All US
stations begin with ‘K’, Canadian stations
begin with ‘C’
• Next 3 characters identify the station.
– KJAN is Jackson, MS for example
Date/Time
• Example = 121553Z
• Given in Greenwich Mean Time, or Zulu
• First two numbers are the day of the month.
Single dates are reported with a 0
• Next 4 numbers are the time.
Report Modifier
• Example = AUTO
• 3 possibilities: None, AUTO and COR
• AUTO means the observation was taken
without human interaction or oversight
• COR indicates a correction to a previous
report
• If nothing, then a human took the observation
Wind Direction and Speed
• Example = 21016G24KT 180V240
• First three numbers denote the direction given
in degrees.
• The next two numbers are speed in knots
• In this example, the G indicates that a gust
occurred.
• The second group, 180V240, indicates a wind
shift occurred or it is variable
• Calm winds are reported as 00000KT
Wind Direction/Speed Examples
27005KT indicates a wind that is blowing from
270 degrees (i.e. from the west) at a speed of
5 knots
16018G35KT indicates a wind that is blowing
from 160 degrees (i.e. from the southsoutheast) at a speed of 18 knots with gusts to
35 knots.
Visibility
• Example = 1SM
• ‘SM’ is Statute Miles
• 10SM would indicate a visibility of 10 statute
miles
• 2 1/2SM would indicate a visibility of 2.5
statute miles
• M at the beginning would mean less than the
reported number
– M1/4SM indicates a visibility of less than 0.25
statute miles
Runway Visual Range
• Example = R11/P6000FT
• The first number indicates the runway
• Range is given, after the slash, in feet
Present Weather
• Example = -RA BR
• The weather occurring at, or in the vicinity of,
the observation point at the time of reporting
• There are 5 categories, constructed in
sequences, to consider: Intensity, Descriptor,
Precipitation, Obscuration, Other Weather
Present Weather - Intensity
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Example = -RA BR
Intensity: -, +, VC
- = Light (.10”/hour or .01” in 6 minutes)
+ = Heavy (.30”/hour or .03” in 6 minutes)
VC = in the vicinity of station
Moderate precip has no symbol
Present Weather - Descriptors
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MI = Shallow
PR = Partial
BC = Patches
DR = Low Drifting
BL = Blowing
TS = Thunderstorm
FZ = Freezing
SH = Shower
Present Weather - Precipitation
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Example = -RA BR
DZ = Drizzle
RA = Rain
SN = Snow
SG = Snow Grains
IC = Ice Crystals
PE = Ice Pellets
GR = Hail
GS = Small Hail/Snow Pellets
UP = Unknown Precip
Present Weather - Obscurations
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Example = -RA BR
BR = Mist
FG = Fog
FU = Smoke
VA = Volcanic Ash
SA = Sand
HZ = Haze
PY = Spray
DU = Widespread Dust
Present Weather - Other
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SQ = Squalls
FC = Funnel Cloud, Tornado or Waterspout
SS = Sandstorm
DS = Duststorm
Present Weather Examples
-TSRA indicates a thunderstorm with light rain.
-RA FG indicates light rain and fog.
Sky Conditions
• Example = SCT060
• First three letters represent the amount the
sky is covered
• Next three numbers are the height of the
cloud base in hundreds of feet
• Up to 3 cloud layers may be reported to a
height of 12,000 feet
Sky Conditions Cont.
FEW
SCT
BKN
OVC
CLR
indicates 1/8 to 2/8 sky coverage.
indicates 3/8 to 4/8 sky coverage.
indicates 5/8 to 7/8 sky coverage.
indicates 8/8 sky coverage.
indicates clear conditions
Sky Conditions Example
SCT060 indicates 3/8 to 4/8 sky (scattered)
coverage by a layer of clouds at 6000 feet
above the surface.
BKN039 OVC100 indicates 5/8 to 7/8 (broken)
sky coverage at 3900 feet and 8/8 (overcast)
sky coverage at 10,000 feet.
Temperature/Dewpoint
• Example = 06/04
• Temperature is given first, followed by the
dewpoint. Both are rounded to the nearest
whole Celsius degree
• Negative readings are coded with a ‘M.’
Example, 01/M01 is temp = 1C, dew = -1C
Altimeter
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•
•
•
Example = A2990
Always coded with an ‘A’
Given in inches of mercury
It is the barometric pressure of the location if
it were at sea level
• A2990 = 29.90 inches of mercury
The Remarks Section
• Added only when appropriate
• Up to 26 different items can be reported in
this section
• ‘RMK’ indicates the beginning of the Remarks
section
Example Remarks
• TORNADO B13 6 NE
– Means a tornado began 13 minutes after the hour
and was located 6 miles northeast of the station
• PK WND 20032/25
– Indicates the strongest (peak) wind since the last
observation
– Direction (200), speed of gust (32 knots) and time
of gust (25)
Example Remarks
• Precip Start/Stop Times
– RAB07
– Coded with type of precip, followed by a B for
began or E for ended
– Last numbers indicate minute of the hour the
precip began/end
– May be coded together (RAB07E24)  indicates
rain began at 7 after and ended at 24 after the
hour
Example Remarks
• Sea Level Pressure
– SLP125
– Given in millibars
– SLP stands for sea-level pressure, followed by the last
three digits of the reading
– A decimal point is placed between the last two digits
– Rule of thumb: If the number is less than 500, place a
10 in front. If more than 500, place a 9 in front
– SLP125  1012.5 mb
– SLP955  995.5 mb
Example Remarks
• Hourly Precip Amount
– P0003
– Given in hundredths of an inch. Amount recorded
since the last observation
– Trace of precip is reported as P0000
• 6-Hour Precip
– Similarly to hourly, but 60009
• 24-Hour Precip
– Coded with a 7 in front  70009
– Reported at 12Z, amount recorded in last 24 hours
Example Remarks
• Precise Temp/Dewpoint
– T00640036
– Exact temperature and dewpoint reading to the
tenth of a degree
– Begins with a T followed by two 4 digits groups,
the first is temp and the second is dewpoint
– The first digit is always the sign; if 0, then the
reading is positive, if 1, then it is negative
– In the example, the exact temp = 6.4 degrees C
and dewpoint = 3.6 degrees C