Occluded fronts are the most challenging to visualize in 3-D. Three "domes" of air occur in association with an occluded front (warm sector, cool sector, and cold sector). An occluded front forces the warmer domes of air (the cool sector and warm sector) to rise above the cold sector. The surface warm air sector is in the region between the cold and warm front. In the vertical, this warm air is being rapidly forced upwards over the surface warm front. As this warm / moist air rises in the vertical, it releases an enormous amount of latent heat. Nor'easters are classified as CISK storms (Convective Instability of the Second Kind). The release of latent heat warms the air, insuring the warm sector will rise all the way from the surface to high in the troposphere as it wraps around the low center. While a cold front forces warmer air to rise, an occluded front forces both cool air and warm air to rise. This means the warm / moist air is forced to rise TWICE, once by lifting over the warm front and second by lifting over the occluded front. As a low becomes progressively occluded (cold air wraps completely around cyclone), the warm air is unable to wrap into the low pressure center. At this point the cyclone will weaken.