They are generally seen when a warm or occluded front is approaching.

Later in their life cycle, cyclones form what is called an occluded front.

Occluded fronts usually form around mature low pressure areas.

Precipitation may last for several days, depending on the speed of the occluded front it accompanies.

Occluded fronts have an area of warm air aloft.

In areas where cold fronts catch up to the warm front, the occluded front develops.

An occluded front is a weather pattern.

When they catch up with the preceding warm front, the portion of the boundary which does so is then known as an occluded front.

Initially attached to an occluded front, the low detached from the system and gradually acquired tropical characteristics.

Cloud and rain form along the occluded front until temperatures become equal as the cold and warm air mix.

An occluded front is formed when a cold front overtakes a warm front.

This is an occluded front.

The cold front catches up to the westward portion of the warm front, forming an occluded front.

Occluded Front.

The occluded front extended from Lake Huron to Pennsylvania on September 13.

Nor'easters are associated with warm fronts, cold fronts, or occluded fronts.

In an occluded front, a cold front overtakes a moving warm front, like an army swarming over a fleeing enemy.

Rainbands ahead of warm occluded fronts and warm fronts have little upward motion.

Occluded fronts are indicated on a weather map by a purple line with alternating half-circles and triangles pointing in direction of travel.

The former occluded front to its northwest became a warm front which moved back to the west around the strengthening, and now dominant, southern low pressure center.

However, an occluded front has the entire West Coast socked in, with Los Angeles reporting zero visibility.

They also can occur under altostratus cloud preceeding a warm or occluded front, when cumulus usually lose vertical development as the sun's heat decreases.

Occluded fronts form late in the cyclone life cycle near the center of the cyclone and often wrap around the storm center.

Cold fronts and occluded fronts generally move from west to east, while warm fronts move poleward.

At the same time, an associated occluded front moved into Northern England, becoming very active as it did so with the peak rainfall on 15 June.