Interactions of the winter lake-effected boundary layer with synoptic systems

Many papers have been written about lake-effected boundary layers and lake-effect snow storms. However, little research has been published on interactions of these lake-effected boundary layers with synoptic systems. In this presentation we will describe simulations and observations of two such interactions 1) seeding of lake-effect boundary layer convective clouds over Lake Michigan by snow falling from higher, cyclone-generated cloud layers 2) impacts of the lake-effected boundary layer on a synoptic cold front crossing Lake Michigan.

Simulations of 5 December 1997, show that even very light seeding of shallow lake-effect boundary layer clouds produced deeper clouds, enhanced vertical motions, increased precipitation production and larger snow mass concentrations in agreement with Lake-ICE observations. Simulations further revealed that the snowfall was dominated by the lake-effect clouds, but the very light seeding produced a measurable enhancement. Cold front interaction with the relatively warm convective lake-effect boundary layer early on 10 January 1998 resulted in a slowing of the frontal progress over the lake, a deepening of the clouds and increased precipitation from the cold front. Simulations further showed that the impacts were dominated by the heat and moisture fluxes from the lake surface rather than surface roughness differences over the lake.