Occluded Front

When a warm front takes over a cold front

Formation of an Occluded Front

The formation of an Occluded front all begins with a developing cyclone (an area of low pressure around which the winds flow counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere) which typically has a preciding warm front and an even faster moving cold front. North of the warm front is a mass of cooler air that was in place before the storm even entered the region. As the storm intensifies the cold air wraps around the warm front-this forms an occluded front, which is the boundary that separates the new cold air mass (to the west) from the older cool air mass already in place north of the warm front.

-Symobolically on a map an occluded front is represented by a solid line with alternating triangles and circles pointing the direction the front is moving. On colored weather maps, the front is drawn with a solid purple line.

Common Characteristics Assosiated With an Occluded Front

	Before Passing	While Passing	After Passing
Winds	southeast-south	variable	west to northwes
Temp- Cold Type Warm Type	cold-cool cold	dropping rising	colder milder
Pressure	usually falling	low point	usually rising
Precipitation	light, moderate or heavy	light, moderate, heavy continuous precip, or showers	light to moderate precip, followed by clearing.
Visibility	poor in precip	poor in precip	improving

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