Mean State Critical Level (MSCL) is the level in the atmosphere where cross-barrier winds drop to zero.
This is a relevant feature for mountain wave and downslope windstorm development. The presence of MSCL acts as a lid in the atmosphere, reflecting gravity waves downward in the lee of a mountain range. It has been found in Duine et al. 2025 that lee slope winds accelerate more in situations with than without MSCL, amplifying hazardous winds and enhancing wildfire conditions.
Usage: The level is found from a vertical profile upstream of the mountain range. Can be applied to both radiosondes and model data
This script was developed and applied in:
Duine, G.J., LMV. Carvalho, C. Jones, CF. Thompson, W.O.J. Brown, J. Dumas, D. Gomberg, T. Hall and R. Kittell, 2025: The Relevance of Mean-State Critical Levels for the Intensification of Downslope Winds in a Coastal Mountainous Environment. Weather Forecast., 40(2), 307-318 https://journals.ametsoc.org/view/journals/wefo/40/2/WAF-D-24-0084.1.xml