NDV= No Directional Variation....of visibility sensors. Used if its an automated station.
/// denotes that the 'automated' station cannot detect the 'type' of cloud group at this level.
cl12pv2s
FYI:
o Although all possible types of present weather cannot be coded automatically, equipment is developing and new
codes are appearing in the METAR AUTO: DZ or FG or BR or RA or SN or FZFG or SHRA or SHSN or FZRA or FZDZ.
o The abbreviation UP is used to indicate when it has not been possible to identify precipitation using the automatic observation
system.
o The attribute VC (vicinity) is not normally used by automatic systems; however certain sites can code VCTS (thunderstorms
close to airfield, i.e. between 8 and 16 km from the airfield).
o The symbol /// is inserted after the cloud code group to show that the type of cloud cannot be observed by the automatic
system.
o The abbreviation NCD is inserted in place of the cloud code group when no cloud has been detected by the automatic
system and when the system is not capable of detecting the absence of CB or TCU.
o The abbreviation NSC is inserted in place of the cloud code group when the automatic system has not detected any
cloud and the system is capable of detecting the absence of CB or TCU.
o The symbol ////// is used in front of CB (or TCU) where the automatic system has detected a CB (or TCU) and where
the coverage (or height) of these clouds has not been measured.
o The abbreviation REUP should be used to indicate that the automatic system has been unable to identify a recent precipitation.