Sky Condition Group
To help explain the different parts of the cloud group, we will use the example SCT015
The numbers in the above example indicate the height of the cloud layer or vertical
visibility into the layer. This number is in hundreds of feet above ground level (AGL), so
the number 015 would be 1,500 feet AGL and the 030 would be 3,000 feet AGL.
Sky cover classifications describe cloud layers or obscuring phenomena. Classifications
such as SCT and OVC indicate sky cover. To determine the correct classification,
weather personnel divide the sky into eighths, figure out how much of the sky is
covered, and then select the correct classification. Table 1-18 provides the
classification, its meaning, and the associated amount of sky coverage.
Sky Cover Amount
SKC or CLR (1)
Clear Sky without clouds or
A few clouds are present
>0/8 to and including 2/8
Scattered clouds are present
3/8 to and including 4/8
Broken More than half, but not all of
5/8 to and including 7/8
the sky is covered
Overcast The sky is covered by
Vertical visibility The sky is totally
obscured by obscuring phenomena
(1) CLR is used by ASOS when no clouds below 12,000 feet are detected; SKC is used
when a manual observation determined there are no clouds present.
(2) A partial obscuration could make up part or all of these classifications.
Table 1-18 -- Sky cover classification
Temperature and Dew Point Group
The temperature and the dew point are encoded to the nearest whole degree Celsius
using two digits. If either the temperature or dew point is below zero, it is preceded by a
capital letter "M."
For example, a temperature of 2°C with a dew point of -8°C is encoded as "02/M08."