Reading and Interpreting METARs


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METAR KPIT 020256Z 02003KT 10SM TSRA OVC01OCB SCT100 BKN130 18/17 A2996

METAR's will always be published in the same order

The METAR code uses International Civil Aviation Organization (ICAO) four-letter station identifiers that follow the type of report. In the continious United States, the three-letter identifier is prefixed with K. For example SEA (Seattle) becomes KSEA. Elsewhere, the first one or two letters of the ICAO identifier indicate in which region of the world and country (or state) the station is located. Pacific locations such as Alaska, Hawaii, and the Mariana Islands start with P followed by an A, H, or G respectively. The last two letters reflect the specific reporting station identification. If the location’s three-letter identification begins with an A, H, or G, the P is added to the beginning. If the location’s three-letter identification does not begin with an A, H, or G, the last letter is dropped and the P is added to the beginning.

METAR KPIT 202253Z AUTO 00000KT 1SM R35L/4500V6000FT -RA BR BKN030 10/10 A2990 RMK AO2

The date and time the observation is taken are transmitted as a six-digit date/time group appended with Z to denote Coordinated Universal Time (UTC). The first two digits are the date (day 20 of current month) followed with two digits for hour and two digits for minutes (2253, translates to 1753 (5:53pm) Eastern). If a report is a correction to a previously disseminated erroneous report, the time entered on the corrected report shall be the same time used in the report being corrected.

METAR KPIT 140651Z AUTO 00000KT 1SM R35L/4500V6000FT -RA BR BKN030 10/10 A2990 RMK AO2

The modifier element, if used, follows the date/time element. The modifier, AUTO, identifies a METAR/SPECI report as an automated weather report with no human intervention. If AUTO is shown in the body of the report, AO1 or AO2 will be encoded in the remarks section of the report to indicate the type of precipitation sensor used at the station. A remark of AO1 indicates a report from a station that does not have a precipitation discriminator, and an AO2 remark indicates a report from a stationwhich has a precipitation discriminator. The absence of AUTO indicates that the report was made manually or the automated report had human augmentation/backup.

The modifier, COR, identifies a corrected report that is sent out to replace an earlier report with an error.

WIND

METAR KPIT 140651Z AUTO 01004KT 1SM R35L/4500V6000FT -RA BR BKN030 10/10 A2990 RMK AO2

The wind element is reported as a five-digit group (six digits if speed is over 99 knots). The first three digits (010) are the direction from which the wind is blowing in tens of degrees referenced to true north (in the above case; 10°). Directions less than 100 degrees are preceded with a zero. The next two digits (04) are the average speed in knots (in the above case; 04 knots), measured or estimated, or if over 99 knots, the next three digits.

Example:
  • 340105KT
If the wind speed is less than 3 knots, the wind is reported as calm, 00000KT. If the wind is gusty, 10 knots or more between peaks and lulls, 'G' denoting gust, is reported after the speed followed by the highest gust reported. The abbreviation KT is appended to denote the use of knots for wind speed. Other countries may use kilometers per hour or meters per second.

If the wind direction is variable by 60 degrees or more and the speed is greater than 6 knots, a variable group consisting of the extremes of the wind directions separated by V will follow the wind group.

Example:
  • 08012G25KT 040V120
The wind direction may also be considered variable if the wind speed is 6 knots or less and is varying in direction (60-degree rule does not apply). This is indicated with the contraction VRB.

Example:
  • VRB04KT
WIND REMARKS
At facilities that have a wind recorder or at automated weather reporting systems, whenever the peak wind exceeds 25 knots, PK WND will be included in the Remarks element in the next report. The peak wind remark includes three digits for direction and two or three digits for speed followed by the time in hours and minutes of occurrence. If the hour can be inferred from the report time, only the minutes are reported.

Example:
  • PK WND 28045/15
When a windshift occurs, WSHFT will be included in the Remarks element followed by the time the windshift began (with only minutes reported, if the hour can be inferred from the time of observation). A windshift is indicated by a change in wind direction of 45 degrees or more in less than 15 minutes with sustained winds of 10 knots or more throughout the windshift. The contraction, FROPA, may be entered following the time if the windshift is the result of a frontal passage.

VRB - This code represent winds that are less than 6 knots, and variable in direction.

VISIBILITY:
The visibility portion of the METAR can be coded in many different ways.
  • Statute miles
  • Meters
  • Runway Visual Range
METAR KPIT 140651Z AUTO 00000KT 08 5SM R35L/4500V6000FT -RA BR BKN030 10/10 A2990 RMK AO2

Prevailing visibility is reported in statute miles followed by a space, fractions of statute miles, as needed, and the letters SM (08 5SM = 08.5 statute miles). Other countries may use meters or kilometers. Prevailing visibility is considered representative of the visibility conditions at the observing site. Prevailing visibility is the greatest visibility equaled or exceeded throughout at least half the horizon circle, which need not be continuous. When visibilities are less than 7 miles, the restriction to visibility will be shown in the weather element. The only exception to this rule is that if volcanic ash, low drifting dust, sand, or snow is observed, it is reported, even if it does not restrict visibility to less than 7 miles.

VISIBILITY REMARKS
If tower or surface visibility is less than 4 statute miles, the lesser of the two will be reported in the body of the report; the greater will be reported in the Remarks element.

Example:
  • TWR VIS 1 1/2 or SFC VIS 1 1/2
Automated reporting stations will show visibility less than 1/4 statute mile as M1/4SM and visibility 10 or greater than 10 statute miles as 10SM.

For automated reporting stations having more than one visibility sensor, site-specific visibility (which is lower than the visibility shown in the body) will be shown in the Remarks element.

Example:
  • VIS 2 1/2 RWY 11
When the prevailing visibility rapidly increases or decreases by 1/2 statute mile or more during the observation, and the average prevailing visibility is less than 3 statute miles, the visibility is variable. Variable visibility is shown in the Remarks element with the minimum and maximum visibility values separated by a V.

Example:
  • VIS 1/2V2
Sector visibility is shown in the Remarks element when it differs from the prevailing visibility and either the prevailing or sector visibility is less than 3 miles.

Example:
  • VIS NE 2 1/2
WEATHER PHENOMENA
METAR KPIT 140651Z AUTO 00000KT 1SM R35L/4500V6000FT -RA BR BKN030 10/10 A2990 RMK AO2

Weather phenomena is broken into two categories: qualifiers and weather phenomena.

Intensity may be shown with most precipitation types.
A "-" denotes a light intensity level, no symbol denotes a moderate intensity level, and a "+" denotes a heavy intensity level. When more than one type of precipitation is present, the intensity refers to the first precipitation type (most predominant). In the above METAR "-RA BR" would translate as Light Rain, Mist, Limited (restricted) Visibility.

Example:
  • +SHRASN indicates heavy rainshowers and snow.
Proximity
Proximity is applied to and reported only for weather phenomena occurring in the vicinity of the airport. Vicinity of the airport is defined to be between 5 and 10 miles of the usual point of observation for obscuration and just beyond to point of observation to 10 miles for precipitation. It is denoted by VC. Intensity and VC will never be shown in the same group.

Examples:
  • VCSH indicates showers in the vicinity of the airport.
  • VCFG indicates fog in the vicinity of the airport.
Descriptor
The eight descriptors shown below further identify weather phenomena and are used with certain types of precipitation and obscurations. Although TS and SH are used with precipitation and may be preceded with an intensity symbol, the intensity still applies to the precipitation and not the descriptor.

Example:
  • +TSRA is a thunderstorm with heavy rain and not a heavy thunderstorm with rain.
Descriptor Qualifiers
Descriptor
MI1Shallow
BC2Patches
DR3Low Drifting
BL4Blowing
SHShowers
TSThunderstorm
FZFreezing
PRPartial
  • 1MI shall be used only to further describe fog that has little vertical extent (less than 6 feet).
  • 2BC shall be used only to further describe fog that has little vertical extent and reduces horizontal visibility.
  • 3DR shall be used when dust, sand, or snow is raised by the wind to less than 6 feet.
  • 4BL shall be used when dust, sand, snow, and/or spray is raised by the wind to a height of 6 feet or more.
If more than one significant weather phenomenon is observed, entries will be listed in the following order: Tornadic activity, thunderstorms, and weather phenomena in order of decreasing predominance (i.e., the most dominant type is reported first).

If more than one significant weather phenomenon is observed, except precipitation, separate weather groups will be shown in the report. No more than three weather groups will be used to report weather phenomena at or in the vicinity of the station. If more than one type of precipitation is observed, the appropriate contractions are combined into a single group with the predominant type being reported first. In such a group, any intensity will refer to the first type of precipitation in the group.

Examples:
  • TSRA indicates thunderstorm with moderate rain.
  • +SHRA indicates heavy rainshowers.
  • -FZRA indicates light freezing rain.
Precipitation
The types of precipitation in the METAR code are shown in Table 2-4. Precipitation is any form of water particle, whether liquid or solid, that falls from the atmosphere and reaches the ground.

Examples:
  • GR is used to indicate hail ¼ inch in diameter or larger.
  • GS is used to indicate hail less than ¼ inch in diameter.
  • UP is unknown precipitation and is used only at automated sites. This occurs when light precipitation is falling but the precipitation discriminator cannot determine the precipitation type. This situation usually occurs when rain and snow are falling at the same time.
Obscurations
The types of obscuration phenomena in the METAR code are shown in Table below. They are any phenomena in the atmosphere, other than precipitation, that reduce horizontal visibility.

Examples:
  • BR is used to indicate mist restricting visibility and is used only when the visibility is from 5/8 mile to 6 miles.
  • FG is used to indicate fog restricting visibility and is used only when visibility is less than 5/8 mile.
Other
The other weather phenomena, shown in the table, are reported when they occur.

Examples:
  • SQ is a sudden increase in wind speed of at least 16 knots, the speed rising to 22 knots or more, and lasting at least 1 minute.
  • +FC is used to denote a tornado or waterspout.
  • FC is used to denote a funnel cloud.
Weather Phenomena
PrecipitationObscurationOther
DZ Drizzle
RA Rain
SN Snow
SG Snow grains
IC Ice crystals
PL Ice pellets
GR Hail
GS Small hail or Snow pellets
UP Unknown precipitation
BR Mist
FG Fog
DU Dust
SA Sand
HZ Haze
PY Spray
VA Volcanic ash
FU Smoke
PO Dust/Sand whirls
SQ Squalls
FC Funnel cloud
+FC Tornado or Waterspout
SS Sandstorm
DS Dust storm

Weather Begins/Ends
When weather begins or ends, the Remarks element will show the beginning and ending times of any type of precipitation or thunderstorms. Types of precipitation may be combined if beginning or ending times are the same.

Example:
  • RAB05E30SNB30E45 This means that rain began at 5 minutes past the hour and ended at 30 minutes past the hour, snow began at 30 minutes past the hour and ended at 45 minutes past the hour.
Example:
  • TSB05E45 This means a thunderstorm began at 5 minutes past the hour and ended at 45 minutes past the hour.
Hailstone Size
When hailstones, GR, are shown in the body of a report, the largest hailstone size is shown in the remarks element in 1/4-inch increments and identified with the contraction GR. Hailstones less than 1/4 inch are shown in the body of a report as GS and no remarks are entered indicating hailstone size.

Example:
  • GR 1 ¾
SKY CONDITION
METAR KPIT 140651Z AUTO 00000KT 1SM R35L/4500V6000FT -RA BR BKN030 10/10 A2990 RMK AO2

Sky condition is reported in the following format:
Amount/Height/Type (as required) or Indefinite Ceiling/Height (Vertical Visibility)

AMOUNT
A clear sky, a layer of clouds, or an obscuring phenomenon is reported by one of the six sky cover contractions. When more than one layer is reported, they are reported in ascending order of height. The above METAR (BKN030) reports Broken Cloud cover at 30,000 Feet. For each layer above a lower layer or layers, the sky cover for that higher layer will be the total sky cover that includes that higher layer and all lower layers. In other words, the summation of the cloud layers from below and at that higher level determines what sky cover is reported. This summation includes . both clouds and obscuration. The amount of sky cover is reported in eighths of the sky, using the contractions in the table below.

Reportable Contractions for Sky Cover
Reportable ContractionsMeaningSummation Amount
*SKC or CLRClear0 or 0 below 12,000
FEWFew>0 but 2/8
SCTScattered3/8-4/8
BKNBroken5/8-7/8
OVCOvercast8/8
VVVertical Visibility (indefinite ceiling)8/8

*SKC will be reported at manual stations. The abbreviation CLR shall be used at automated stations when no clouds below 12,000 feet are detected.

Note: For aviation purposes, the ceiling is defined as the height (AGL) of the lowest broken or overcast layer aloft or vertical visibility into an obscuration.

HEIGHT
Cloud bases are reported with three digits in hundreds of feet above ground level.

Example:
  • SCT020
Clouds above 12,000 feet cannot be detected by automated reporting systems. At reporting stations located in the mountains, if the cloud layer is below the station level, the height of the layer will be shown as three solid slashes (///).

Example:
  • SCT///
TYPE (AS REQUIRED)
If towering cumulus clouds, TCU, or cumulonimbus clouds, CB, are present, they are reported after the height that represents their base.

Example:
  • BKN025CB or SCT040TCU
INDEFINITE CEILING/HEIGHTS (VERTICAL VISIBILITY)
The height into an indefinite ceiling is preceded with VV followed by three digits indicating the vertical visibility in hundreds of feet above ground level. The layer is spoken as "indefinite ceiling" and indicates total obscuration.

Example:
  • VV002
Partial Obscurations
The amount of obscuration is reported in the body of the METAR when the sky is partially obscured by a surface-based phenomenon by indicating the amount of obscuration as FEW, SCT, or BKN followed with three zeros (000). The type of obscuring phenomenon is stated in the Remarks element and precedes the amount of obscuration and three zeros. For example, if fog is hiding >1/8 to 2/8 of the sky, it will be coded in the body of the METAR as "FEW000." Because the fog is partially obscuring the sky, a remark is required.

  • Example of Remark: FG FEW000.
The sky cover and ceiling, as determined from the ground, represent as nearly as possible what the pilot should experience in flight. In other words, a pilot flying at or above a reported ceiling layer (BKNOVC) should see less than half the surface below. A pilot descending through a surface-based total obscuration should first see the ground directly below from the height reported as vertical visibility into the obscuration. However, due to the differing viewing points of the pilot and the observer, the observed values and what the pilot sees do not always exactly agree.

ADDITIONAL SKY CONDITION REMARKS
Whenever the ceiling is below 3,000 feet and is variable, the remark CIG will be shown in the Remarks element followed with the lowest and highest ceiling heights separated with a V.

Example:
  • CIG 005V010
When an automated station uses meteorological discontinuity sensors, site-specific sky conditions that differ from the ceiling height in the body of the report will be shown in the Remarks element.

Example:
  • CIG 002 RWY 11
When a layer is varying in sky cover, the variability range will be shown in the Remarks element. If there is more than one cloud layer of the same coverage, the variable layer will be identified by including the layer height.

Example:
  • BKN014 V OVC
When significant clouds are observed, they are shown in the Remarks element. The following cloud types are shown:

Towering cumulus, TCU, and direction from the station.

Example:
  • TCU W
Cumulonimbus, CB; or cumulonimbus mammatus, CBMAM; direction from the station; and direction of movement (if known). If the clouds are beyond 10 miles from the airport, DSNT will indicate that they are distant.

Examples:
  • CB DSNT E or CBMAM E MOV NE
Altocumulus castellanus, ACC; standing lenticular (stratocumulus, SCSL; altocumulus, ACSL; or cirrocumulus, CCSL); or rotor clouds, ROTOR CLD, will show a remark describing the clouds (if needed) and the direction from the station.

Examples:
  • ACC NW or ACSL SW
TEMPERATURE/DEW POINT GROUP
METAR KPIT 140651Z AUTO 00000KT 1SM R35L/4500V6000FT -RA BR BKN030 M01/M04 A2990 RMK AO2

Temperature/dew point are reported in a two-digit form in whole degrees Celsius separated by a solidus (/). Temperatures below zero are prefixed with M (The above example reports: Temp: -1°C and Dewpoint: -4°C). If the temperature is available but the dew point is missing, the temperature is shown followed by a slash and a blank space (M01/ ). If the temperature is missing, the group is omitted from the report.

ALTIMETER
METAR KPIT 140651Z AUTO 00000KT 1SM R35L/4500V6000FT -RA BR BKN030 10/10 A2990 RMK AO2

The altimeter (barometric pressure) element follows the temperature/dew point group and is the last element in the body of a METAR or SPECI report. It is reported in a four-digit format representing tens, units, tenths, and hundredths of inches of mercury prefixed with A (above METAR reports: 1013 hPa (29.90 inHg)). The decimal point is not reported or stated.

ALTIMETER REMARKS
When the pressure is rising or falling rapidly at the time of observation, Remarks element will show PRESRR or PRESFR respectively.

Some stations also include the sea-level pressure (which is different from altimeter). It is shown in the Remarks element as SLP being the remark identifier followed by the sea-level pressure in hectopascals (h/Pa), a unit of measurement equivalent to millibar (mb).

Example:
  • SLP982
REMARKS (RMK) (AS REQUIRED)

METAR KPIT 140651Z AUTO 00000KT 1SM R35L/4500V6000FT -RA BR BKN030 10/10 A2990 RMK AO2 SLP135 T10061039

Remarks will be included in all observations, when appropriate, in the order as presented in the table below. The contraction RMK follows the altimeter in the body and precedes the actual remarks. Time entries will be shown as minutes past the hour if the time reported occurs during the same hour the observation is taken. If the hour is different, hours and minutes will be shown. Location of phenomena within 5 statute miles of the point of observation will be reported as at the station. Phenomena between 5 and 10 statute miles will be reported as in the vicinity, VC. Phenomena beyond 10 statute miles will be shown as distant, DSNT. Direction of phenomena will be indicated with the eight points of the compass (i.e., N, NE, E, SE, S, SW, W, NW). Distance remarks are in statute miles except for automated lightning remarks that are in nautical miles. Movement of clouds or weather will be indicated by the direction toward which the phenomenon is moving.

There are two categories of remarks: automated, manual, and plain language; and additive and automated maintenance data.

AUTOMATED, MANUAL, AND PLAIN LANGUAGE REMARKS CATEGORY
This group of remarks may be generated from either manual or automated weather reporting stations and generally elaborate on parameters reported in the body of the report.

Automated, Manual, and Plain Language Remarks
RemarksExamples of Remarks
1. Volcanic EruptionsMT. AUGUSTINE VOLCANO 70 MILES SW ERUPTED 231505 LARGE ASH CLOUD EXTENDING TO APRX 30000 FEET MOVING NE
2. Tornado, Funnel Cloud, or WaterspoutTORNADO B13 6 NE
3. Automated Station TypeAO1 (Automated Station w/ Precip. Discriminator)
AO2 (Automated Station w/o Precip. Discriminator)
4. Peak WindPK WND 28045/15
5. WindshiftWSHFT 30 FROPA
6. Tower Visibility or Surface VisibilityTWR VIS 1 ½ or SFC VIS 1 ½
7. Variable Prevailing VisibilityVIS 1/2V2
8. Sector VisibilityVIS NE 2 ½
9. Visibility at Second SiteVIS 2 ½ RWY 11
10. LightningOCNL LTGICCG OHD or FRQ LTGICCCCG W
11. Beginning and Ending of PrecipitationRAB05E30SNB20E55
12. Beginning and Ending of ThunderstormTSB05E30
13. Thunderstorm LocationsTS SE MOV NE
14. Hailstone SizeGR 1 ¾
15. VirgaVIRGA NE
16. Variable Ceiling HeightCIG 005V010
17. ObscurationsFU BKN000
18. Variable Sky ConditionBKN014 V OVC
19. Significant Cloud TypesCB W MOV E or CBMAM S MOV E or TCU W or ACC NW or ACSL SW-W
20. Ceiling Height at Second LocationCIG 002 RWY 11
21. Pressure Rising or Falling RapidlyPRESRR or PRESFR
22. Sea-Level PressureSLP982
23. Aircraft Mishap(ACFT MSHP)
24. No SPECI Report TakenNOSPECI
25. Snow Increasing RapidlySNINCR 2/10
26. Other Significant InformationAny other information that will impact aviation operations

Interesting Weather Facts
? LIGHTENING
The air located around a lightning bolt is heated to around 54,032°F (30,000°C). This is 5 times hotter than the surface of the sun.