Temperatures rise slowly with the advance of the front, but more rapidly as the front passes and wind shifts in the clockwise direction. Then the cloud cover begins to break up but the fog often lingers. The front itself is usually marked by a line of towering cumulus and showers. In the most severe cases a line or wall of cumulonimbus marks the front and can be accompanied by thunderstorms and hail. The tops of the cumulonimbus often spread out ahead of the front into dense cirrus called an anvil.
Temperatures fall and the wind shifts in a clockwise direction while the front passes.
The band of cloud and rain is usually quite narrow and passes within a few hours. Afterwards, some non-frontal clouds, such as stratocumulus or cumulus , may develop but just as frequently the skies clear. The sun heating the ground in turn heats the air just above the ground. The warmer air becomes buoyant and rises and cools. As the air cools, the water vapour begins to condense and small fluffy cumulus clouds form.