METAR Tutorial
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-TYPE
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 is met
such as low visibility, low clouds, frozen precipitation, or
thunderstorms.
KORD-Station ID
In this example, K refers to a
US Station and ORD is the three letter id for O' Hare (from Old
Orchard, it's 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 (Universal Time Code).
19020G26KT-Winds
- 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 350, 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 is 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.
6SM-Visibility
- 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 that 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.
|
QUALIFIER |
WEATHER PHENOMENA |
|
INTENSITY OR PROXIMITY
1
|
DESCRIPTOR 2
|
PRECIPITATION 3
|
OBSCURATION 4
|
OTHER 5
|
|
- Light Moderate (see
note 2)
+ Heavy
VC In the Vicinity
(see note 3)
|
MI Shallow
PR Partial
BC Patches
DR Low Drifting
BL Blowing
SH Shower(s)
TS Thunderstorm
FZ Freezing
|
DZ Drizzle
RA Rain
SN Snow
SG Snow Grains
IC Ice Crystals
PL Ice Pellets
GR Hail
GS Small Hail and/or
Snow Pellets
UP Unknown
Precipitation
|
BR Mist
FG Fog
FU Smoke
VA Volcanic Ash
DU Widespread Dust
SA Sand
HZ Haze
PY Spray
|
PO Well-Developed
Dust/Sand Whirls
SQ Squalls
FC Funnel Cloud
Tornado Waterspout (see note 3)
SS Sandstorm
SS Duststorm
|
- 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.
|
BKN070-Sky Condition
- 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 indefinate 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 indefinate ceiling.
- Significant Clouds such as
TCU (Towering Cumulus), CB, (Cumulonimbus, or a
shower/thunderstorm), or ACC (Altocumulus Castellanus) will be
found on the en 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.
30.16-Altimeter/Pressure
- A simply stands for
Altimeter
- 3016 means 30.16 inches of
mercury for the pressure.
RMK AO2-REMARKS
- RMK simply means REMARKS
and marks the end of the standard metar observation and the
beginning of the remarks that are put in as necessay.
- 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###)
- T=Temp
- 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=RVR
- 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
|
Primary
Requirement |
Description
|
Code Figure
|
Atmospheric
pressure
now higher than
3 hours ago. |
Increasing, then decreasing. |
0 |
Increasing, 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 more rapidly. |
8 |
|
|
|
Ken
Caryl - NDS Weather
