Cold Occlusions

Cold occlusions occur when a faster moving cold front overtakes a slower warm front. When the cold air forces the warm air upward, this is a cold occlusion. (the cold air might also ride up over the warm air).  A cold occlusion is nothing more than a warm front aloft.  If the air behind the occlusion is colder than the air ahead of the warm front, then it is a cold occlusion. 

Surface temperatures are fairly cool ahead of the front and drop to much colder after the front passes. Since cold air holds less moisture than warm air, surface dew points will fall. Visibility and weather are usually poor before and during passage, but improve after passage.  Pressures fall ahead of the front. Pressures reach the lowest point during passage of the front and rise after passage. Surface winds can be gusty. Winds are usually from the south to southeast before passage and rotate clockwise to the west - northwest after passage (veering winds).

Concept Mapping Toolkit
Insitute for Human and Machine Cognition
The University of West Florida