The following is an example of a METAR, a surface observation, from O' Hare Airport. Just click on any of the cells to go to the help dealing with that particular section.
METAR is the scheduled observation taken at the end of each hour. SPECI is an observation taken at an unscheduled time due to certain criteria that are met such as low visibility, low clouds, frozen precipitation, or thunderstorms.
In this example, K refers to a US Station and ORD is the three letter id for O' Hare (from Orchard Field, its original name). Other examples are KRFD (Rockford Il), KAMA (Amarillo, TX) and KDEN (Denver, Co).
041656Z-Time and Date
- The 04 represents the day of the month.
- The 1656 represents the time at which the observation went out.
- The Z represents that the time is in ZULU or UTC (Coordinated Universal Time).
- The 190 (the first three numbers) is the direction of the winds in degrees from 0 to 360 degrees (although you will never see 360 because after 359, it goes back to 0).
- The 20 (next two numbers) is the speed of the winds in knots.
- the G26 represents the wind gusts. In this case the gusts are 26 knots. Gust will not always be on here...there are criteria which must be met in order to have a gust. Simply, unless it's windy, you are not going to see gusts in the obsevation.
- the KT simply means knots. It will always be at the end.
- For winds speeds below 7 knots, you might see VRB005KT which means the wind direction is variable. This is the idea of "light and variable" that you might see in a forecast.
- For winds greater than 6 knots you might see 18015KT 150V210. The winds are from 180 degrees at 15 knots, but the direction is actually variable between 150 degrees and 210 degrees. In order to be variable above 6 knots, the winds must have at least a 60 degree variation.
- The 6SM simply means 6 Statute Miles. Occasionally you might see visibility up to 20 or 30 SM but for the most part it will go from < 1/4 (vis below 1/4 SM) up to 10 SM.
(-SHRA)-Present Weather and Obscurations
- (-) is the designator for light. Precipitation will either be light (-), moderate ( ), or heavy (+) based on certain criteria that must be met. For more info on those criteria, please see the FMH-1 link at the bottom of this page. For now, just understand that it is simply the intensity of the snow, rain, hail, sleet, or freezing rain.
- SH means showers and RA means rain. So the present weather is a light rain shower.
- The following is from the FMH-1 HANDBOOK. The entire handbook is linked at the bottom of this page.
INTENSITY OR PROXIMITY 1
- Light Moderate (see note 2)
VC In the Vicinity (see note 3)
DR Low Drifting
SG Snow Grains
IC Ice Crystals
PL Ice Pellets
GS Small Hail and/or Snow Pellets
UP Unknown Precipitation
VA Volcanic Ash
DU Widespread Dust
PO Well-Developed Dust/Sand Whirls
FC Funnel Cloud Tornado Waterspout (see note 3)
- The weather groups shall be constructed by considering columns 1 to 5 in the table above in sequence, i.e. intensity, followed by description, followed by weather phenomena, e.g. heavy rain shower(s) is coded as +SHRA
- To denote moderate intensity no entry or symbol is used.
- Tornados and waterspouts shall be coded as +FC.
- BKN represents a broken sky. (The clouds cover 5/8 to 7/8 of the sky)
- 110 represents the clouds are at 11,000 feet (simply add 2 zeroes to get the height)
- The cloud cover will either be FEW (1/8 TO 2/8 cloud coverage), SCT (SCATTERED, 3/8 TO 4/8 cloud coverage, BKN (5/8-7/8 coverage), and OVC (OVERCAST, 8/8 Coverage).
- You will often have more than 1 designator (i.e. SCT035 BKN090 OVC140)
- An indefinite ceiling caused by fog, rain, snow, etc., will require a designator as VV (Vertical Visibility). VV is the how high you can see vertically into the indefinite ceiling.
- Significant Clouds such as TCU (Towering Cumulus), CB, (Cumulonimbus, or a shower/thunderstorm), or ACC (Altocumulus Castellanus) will be found on the end of a category (i.e. SCT035TCU)
12/08-Temperature and Dewpoint
- 12represents the temperature in Celcius
- 08represents the dewpoint in Celcius
- If the temperature or dewpoint falls below 0 there will be an "M" before it (i.e. 03/M02). "M" means minus.
- A simply stands for Altimeter
- 3016 means 30.16 inches of mercury for the pressure.
- RMK simply means REMARKS and marks the end of the standard metar observation and the beginning of the remarks that are put in as necessary.
- A02 means that the site is automated and HAS a precipitation sensor. If it were AO1, there would be no precip sensor. This does not mean the site is un-manned. If there is an AUTO after the ID in the metar ob, then there is no observer.
There are many remarks, and the FMH-1 (Federal Meteorological Handbook-1) at the bottom will give you a full listing of them. Here are only a few of the important and common remarks:
- Volcanic Eruptions are in plain english
- TORNADO, FUNNEL CLOUD, or WATERSPOUT
- Peak Wind (PK_WND)
- Wind Shift (WSHFT_time)
- BINOVC (Breaks in Overcast)
- BINOVC denotes a few, small clear patches in the overcast sky
- Tower or Surface Visibility (TWR_VIS SFC_VIS)
- CIG (Ceiling=Lowest BKN/OVC layer or height of VV)
- V (Variable)
- i.e. BKN V SCT, VIS 2V3 [2 variable 3 miles], CIG 025V030 [2500 ft-3000ft])
- Lightning (Frequency_LTG-type)
- CG: Cloud to ground
- IC: Intracloud
- CC: Cloud to Cloud
- CA: Cloud to Air
- OCNL: Occasional
- FRQ: Frequent
- CONS: Continuous
- Beginning/Ending of Thunderstorms/Rain/Snow (TSB, SNE, RAB, etc)
- Thunderstorm Location (TS_LOC_(MOV_DIR)
- LOC=Location (N, NE, S, VC, OHD [Overhead], ALQDS [All Quadrants])
- DIR=Direction (N, NE, S, etc)
- Hailstone Size (GR_[size])
- Virga (VIRGA_[ DIR])
- Cumulonimbus or Cumulonimbus Mammatus (CB or CBMAM_LOC_(MOV_DIR).
- Towering cumulus (TCU_[DIR])
- Altocumulus castellanus (ACC_[DIR])
- Standing lenticular or Rotor clouds (CLD_[DIR])
- Pressure Rising or Falling Rapidly (PRESRR/PRESFR)
- Sea-Level Pressure (SLP###)
- Aircraft Mishap (ACFT_MSHP)
- Snow Increasing Rapidly (SNINCR_amount this hour/total)
- Hourly Precipitation Amount (P####).
- 3- and 6-Hour Precipitation Amount (6####)
- 24-Hour Precipitation Amount (7####).
- Snow Depth on Ground (4/###)
- Water Equivalent of Snow on Ground (9####)
- Hourly Temperature and Dewpoint (Tsn###sn###)
- sn=Type (0=above zero celcius, 1=below zero celcius)
- ###=celcius temperature to nearest tenth of a degree
- 6-Hourly Maximum Temperature (1sn###)
- 6-Hourly Minimum Temperature (2sn###)
- 24-Hour Maximum and Minimum Temperature (4sn######)
- First three numbers=maximum temp to nearest tenth of a degree celcius
- Last three numbers=mimimum temp to nearest tenth of a degree celcius
- -Hourly Pressure Tendency (5a###)--see table 12-7 at the bottom for a (type)
- RVR (Runway Visual Range, Rrrr/####ft)--will eventually be in the body!
- r=runway, i.e. 31C, 21L, etc.
- ####ft=Distance of visual range (i.e. 6000ft, P6000ft [plus], m600ft [minus])
Table 12-7. Characteristics of Barometer Tendency
now higher than
3 hours ago.
|Increasing, then decreasing.
|Increasing, then steady, or increasing then
increasing more slowly.
|Increasing steadily or unsteadily.
|Decreasing or steady, then increasing; or
increasing then increasing more rapidly.
same as 3 hours
|Increasing, then decreasing.
|Decreasing then increasing.
lower than 3
|Decreasing, then increasing.
|Decreasing, then steady, or decreasing then
decreasing more slowly.
|Decreasing steadily or unsteadily.
|Steady or increasing, then decreasing; or
decreasing then decreasing more rapidly.