AMC1 MET.TR.205(e)(1) Reporting
of meteorological elements
CLOUD
In local routine report, local special report, METAR and SPECI:
(a) the cloud amount should be reported using
the abbreviations ‘FEW’ (1 to 2 oktas), ‘SCT’ (3 to 4 oktas), ‘BKN’ (5 to7 oktas) or
‘OVC’ (8 oktas);
(b) cumulonimbus clouds and towering cumulus
clouds should be indicated as ‘CB’ and ‘TCU’, respectively;
(c) the vertical visibility should be
reported in steps of 100 ft (30 m) up to 2 000 ft
(600 m);
(d) if there are no clouds of operational
significance and no restriction on vertical visibility and the abbreviation
‘CAVOK’ is not appropriate, the abbreviation ‘NSC’ should be used;
(e) when several layers or masses of cloud of
operational significance are observed, their amount and height of cloud base
should be reported in increasing order of the height of cloud base, and in
accordance with the following criteria:
(1) the lowest layer or mass, regardless of
the amount to be reported as FEW, SCT, BKN or OVC, as appropriate;
(2) the next layer or mass, covering more than
2/8 to be reported as SCT, BKN or OVC, as appropriate;
(3) the next higher layer or mass, covering
more than 4/8 to be reported as BKN or OVC, as appropriate; and
(4) cumulonimbus and/or towering cumulus
clouds, whenever observed and not reported in (1) to (3).
(f) when the cloud base is diffuse or ragged
or fluctuating rapidly, the minimum height of cloud base or cloud fragments,
should be reported; and
(g) when an individual layer (mass) of cloud
is composed of cumulonimbus and towering cumulus clouds with a common cloud
base, the type of cloud should be reported as cumulonimbus only.
EASA aviation regulations require specific cloud reporting in METAR, SPECI, and local reports. Cloud amount is reported in oktas using FEW, SCT, BKN, or OVC. Cumulonimbus (CB) and towering cumulus (TCU) clouds must be indicated. Vertical visibility is reported in 100ft increments. Report cloud layers by height and amount.
* Summary by Aviation.Bot - Always consult the original document for the most accurate information.
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