Weather explained

Sequence of Elements:

  1. location indicator and time stamp

  2. wind direction and speed, gusts if applicable

  3. visibility

  4. runway visual range, if applicable

  5. weather phenomena, if applicable

  6. cloud conditions

  7. air temperature

  8. dew point

  9. QNH

  10. recently observed weather phenomena, if applicable

  11. trend forecast

Location Indicator:
The place where the observation has been made is indicated by the ICAO location indicator.
Wind Direction and Speed, Gusts:
Wind direction is reported in compass degrees in three digits and rounded up or down to the nearest 10 degrees. If the wind is variable, the letters VRB are reported instead of the direction. If the wind is calm, the display indicates 000 for direction and 00 for speed.
Gusts are indicated by the letter "G"; the gust speed appears after the "G". Speed or gusts are followed by the abbreviation of unit of measurement (kt, kmh, or mps).
Additional Regulations:
If during the last 10 minutes the wind speed has exceeded 3 knots and the direction has varied by at least 60 degrees, the variation of direction is reported additionally.
Example: 140V220 spoken as: variable between one four zero and two two zero
Visibility:
Visibility is the ability, as determined by atmospheric conditions and expressed in units of distance, to see and identify prominent unlighted objects by day, and prominent lighted objects by night.
Runway Visual Range (RVR):
The runway visual range is the maximum distance along a runway or landing strip, in the direction of landing or take off, in which the runway lights are still visible. It is reported if the visibility or the runway visual range is below 2000 ft, and is identified by the letter "R".
Together with the runway visual range the tendency is reported:
U=upward N=no change D=downward
Weather Phenomena:
Weather phenomena are entered by means of their abbreviations. If several weather phenomena are observed at the same time, up to 3 phenomena can be reported.
The following table shows all abbreviations, some of which may be combined:
If weather phenomena are combined the prevailing one precedes the others. 
If combinations consist of both qualifier and phenomena the sequence is:
Intensity/Proximity – Descriptor – Weather Phenomena
QUALIFIER WEATHER PHENOMENA
Intensity/Proximity Descriptor Precipitation /  Obscuration /  Others / 
- Light /  MI Shallow /  DZ Drizzle /  BR Mist /  PO Dust- Sand-Whirls / 
  BC Patches / RA Rain /  FG Fog / 
DR Low / 
SN Snow /  FU Smoke / 
SG Snow Grains /  VA Volcanic Ash / 
SQ
Squalls / 
+ Heavy /  BL Blowing /  PL Ice Pellets /
VC In the
Vicinity /
SH Shower /  GR Hail /  DU Dust /  FC Funnel clouds / 
TS Thunderstorm /  GS Snow Pellets /  SA Sand /  SS Sandstorm / 
FZ Freezing /  IC Ice Crystals /  HZ Haze /  DS Duststorm / 
PR Partial / 
MI, PR and BC are only reported in the combination MIFG (shallow Fog), BCFG (Fog Patches) and PRFG (Partial Fog) !!
Cloud Conditions:
Clouds are reported in the sequence of their vertical position, beginning with the lowest, up to four cloud layers can be reported:
1st layer = lowest layer regardless of the coverage  
2nd layer = next cloud layer which has at least a coverage of 3/8  
3rd layer = next layer above which has a coverage of at least 5/8  
4th layer = Cumulonimbus or towering cumulus regardless of the coverage, if not already reported  
Cloud Coverage:
The amount of cloud coverage is determined in eighth, but reported as sky clear, few, scattered, broken or overcast.
No clouds sky clear (SKC)  
1/8 – 2/8 few (FEW)  
3/8 – 4/8 scattered (SCT)  
5/8 – 7/8 broken (BKN)  
8/8 overcast (OVC)  
Cloud Type:
Only cumulonimbus (CB) and towering cumulus (TCU) are reported. The abbreviation follows the cloud base.
Vertical Visibility:
If sky or clouds are not visible due to an obstruction of vision (dense fog or heavy precipitation) vertical visibility (VV) in hundreds of feet is reported instead of cloud coverage and cloud base.
CAVOK:
CAVOK is spoken as "CAV- o-k" and is reported instead of visibility, RVR, weather phenomena and cloud conditions if the following conditions are observed simultaneously:
Visibility: at least 10 km  
No weather phenomena  
Cloud conditions: -no cumulonimbus  
-no clouds below 5000 ft or below highest sector minimum height  
Air Temperature and Dew Point:
Air temperature and dew point are reported in full degrees Celsius (ºC). Values below 0º are indicated by the letter "M"
Air Pressure:
The reported air pressure is called QNH and measured in full hPa (hecto Pascal). Some countries (esp. USA) report air pressure in inches and hundreds of inches mercury. Air pressure in hPa is identified by the letter "Q", in inches by the letter "A".

Conversion Table

 hPa   Inch    hPa  Inch    hPa  Inch    hPa  Inch 
 0990   29.24    1000  29.53    1010  29.83    1020  30.12
 0991  29.27    1001 29.56   1011 29.86   1021  30.15
 0992  29.30   1002 29.59   1012 29.89   1022  30.18
 0993  29.33   1003 29.62   1013 29.92   1023  30.21
 0994  29.36   1004 29.65   1014 29.95   1024  30.24
 0995  29.39   1005 29.68   1015 29.98   1025  30.27
 0996  29.42   1006 29.71   1016 30.01   1026  30.30
 0997  29.44   1007 29.74   1017 30.04   1027  30.33
 0998  29.47   1008 29.77   1018 30.06   1028  30.36
 0999  29.50   1009 29.80   1019 30.09   1029  30.39
Recently Observed Weather Phenomena:
Recently observed weather phenomena are to be reported preceded by "RE"
Example: RETS = recent thunderstorm
Trend Forecast:
If during the next two hours significant weather changes are expected they are forecast by the use of the following terms:
BECMG = becoming
TEMPO = temporary
Together with the time (UTC)
A significant change concerns wind, visibility, weather phenomena and cloud conditions. If a development results in no significant weather "NSW" (no significant weather) is reported.
If no significant change is expected at all, "NOSIG" is reported instead of the trend forecast.
Runway Conditions:
If necessary, runway conditions can be reported by an 8-digit code following the trend forecast.
1st and 2nd digit = number of runway concerned
3rd digit = code for the precipitation type covering the runway
4th digit = code for the extent of precipitation coverage
5th and 6th digit = code for the depth of precipitation coverage
7th and 8th digit = braking action
If the airport is closed due to snow conditions, "SNOCLO" is reported. 
Weather colour state and forecast thereof
The supplementary group is disseminated by meteorological offices at aerodromes of the Bundeswehr.
Weather colour state is a colour state of the current meteorological conditions depending on ground visibility and height of ceiling.
Colour state forecast is a forecast concerning ground visibility and height of ceiling for a period of two hours after the time of observation. Variations or change to another colour state are indicated by change groups (BECMG, TEMPO, FMGG).

 

 

Blue + BLU + no ceiling 8 km below 20000 ft GND
Blue BLU 2500 ft 8 km
White WHT 1500 ft 5 km
Green GRN 700 ft 3.7 km
Yellow YLO 300 ft 1.6 km
Amber AMB 200 ft 0.8 km
Red RED below 200 ft below 0.8 km
Black BLACK Runway not usable for other reasons than
ceiling and / or visibility minima.
Aerodrome Weather Colour Code of the Bundeswehr
( Weather Minima)

Colourstate abbr. Ceiling(5/8) Ground Vis. 1)

Colour state "Black" precedes the current weather colour state.

1) When determing colour states, only ground visibility is
considered - not the runway visual range.

NOTE:
The applicable approach minima for instrument- / radar approach procedures or the failure of landing aids will not be considered when determing the colour states.

Blue + BLU +  
Blue BLU  
White WHT  
Green GRN  
Yellow YLO  
Amber AMB  
Red RED  
Black BLACK  

 

Even though all frequencies and codes SHOULD be real,
they are only for use with ProController, SquawkBox and Flight Simulators,
and should NOT be used for real life aviation.

© 2001
IVAO TH
All Rights Reserved

 Last updated Saturday, 08. June 2002