Forecast the weather from looking at the sky:

High Cloud (16,500 – 45,000 feet)
Cirrus (Ci) – mare’s tails, thin wisps, precipitation possible within 20 – 30 hours (1)
Cirrocumulus (Cc) – often referred to as a “mackerel” sky – often precedes cold or unstable warm fronts – precipitation possible 15 – 20 hours later (2)
Cirrostratus (Cs) – gauzy sheets of cloud often with halos around the sun and moon – precipitation possible within 15 – 25 hours

Middle Clouds (6,500 – 23,000 feet)
Altostratus (As) – “Leaden sky” appearance – precipitation possible
within 10 – 20 hours
Altocumulus (Ac) – clouds appear as large grey rolls, usually precedes a cold
front – precipitation possible within 15 – 20 hours

Low Clouds (6,500 feet and less)
Stratocumulus (Sc) – appears as layers of grey rolls of cloud. These clouds are usually seen during frontal weather and may turn to Stratocumulus (associated with rain and often wind)
Stratus (St) – low grey fog-like cloud usually an indicator of unsettled weather.
Nimbostratus (Ns) – clouds often appear as dark grey towers, with streaks of rain and often associated with wind.
Cumulus (Cu) – Clouds appear as puffs of cauliflower and if there is no vertical movement of cumulus then these are an indicator of fair weather. Cumulus can change in to cumulonimbus
Cumulonimbus (Cb) – Strom clouds, thunderheads often with anvil tops. Precipitation often heavy with wind expected in the near future.