Summary

• The snow band on the 5th was associated with strong low-level convergence between a strong southerly ageostrophic wind south of Lake Ontario, and weaker ageostrophic flow over and downwind of the lake.

• The contrast in ageostrophic flow was due partly to differences in mixing / frictional effects over vs. south of the lake.

• The contrast in ageostrophic flow was due partly to the development of a frontogenetical circulation generated by the presence of a plume of warm air over and downwind of the lake.