Stratospheric Intrusions are when stratospheric air dynamically decends into the troposphere and may reach the surface, bringing with it high concentrations of ozone which may be harmful to some people. Stratospheric Intrusions are identified by very low tropopause heights, low heights of the 2 potential vorticity unit (PVU) surface, very low relative and specific humidity concentrations, and high concentrations of ozone. Stratospheric Intrusions commonly follow strong cold fronts and can extend across multiple states. In satellite imagery, Stratospheric Intrusions are identified by very low moisture levels in the water vapor channels (6.2, 6.5, and 6.9 micron). Along with the dry air, Stratospheric Intrusions bring high amounts of ozone into the tropospheric column and possibly near the surface. This may be harmful to some people with breathing impairments. Stratospheric Intrusions are more common in the winter/spring months and are more frequent during La Nina periods. Frequent or sustained occurances of Stratospheric Intrusions may decrease the air quality enough to exceed EPA guidelines.

Stratospheric Intrusions can be identified as red colored areas on GOES RGB Air Mass imagery on the RAMMB/CIRA "SLIDER" web page.