SPECI shall be issued if since the latest issued special or routine report, the mean surface wind and/or speed changed. SPECI shall be issued, when the onset (Start), cessation (End) or change in intensity of the weather phenomena occurs.

Wind

Wind direction and wind speed are determined by averaging a period 10 minute.


Visibility

If visibility is different in different direction, then in METAR (VVVV) visibility reported will be Prevailing visibility.


Weather Group

In w'w' group, prevailing weather over aerodrome is reported.


Clouds

Height of the base of cloud layers is reported in steps and only significant convective clouds (i.e CB & TCU) are reported by mentioning its type to the cloud group.

Temperatures

In METAR/SPECI:Observed Air temperature and Dew point temperature is reported.

 

Precipitation

In METAR/SPECI: Rain, Showers, drizzle, snow and etc.

 

QNH

In METAR/SPECI:Prevailing air pressure on aerodrome is reported

 

Highest Minimum Sector Altitude (HSMA)

The lowest altitude for emergency conditions.