Added on: January 27, 2018
Pilots are taught that "upslope" stratus or fog occurs when moist air is forced up a mountainside to a level where condensation occurs. As the moist, but unsaturated air is lifted, it expands and cools dry adiabatically. The temperature eventually cools to the dewpoint temperature and fog or stratus can form somewhere along the mountain slope. The truth is that mountains don't necessarily have to be part of the equation. The gradual rise of the terrain from the Midwest to the central High Plains often provides sufficient upglide to develop a solid overcast stratus deck producing a rather large area of marginal VFR and IFR conditions. In this workshop we'll discuss the characteristics of a widespread upslope stratus event in September that occurred over the western-half of Kansas and eastern-half of Colorado.