The Effect of The Gust Front on The Generation of New Convection

197 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1980.The importance of gust fronts in triggering new storm development is widely recognized. A three-dimensional numerical cloud model developed by Klemp and Wilhelmson is used to study the relationship of new convection to previously generated gust fronts. The model has been modified with a vertically stretched grid, a fourth-order conservative approximation for horizontal advection, and an Orlanski type boundary condition. The sounding taken from the multicell Raymer storm that occurred in NHRE on 9 July 1973 is used as the initial environment in the model. Five new cells form about 25-30 min apart due to the downdraft from the previous cell enhancing the convergence along the gust front. A comparison with observation data shows qualitative agreement. Comparison of results with those obtained by other modelers for different storms is also included.The formation of successive cells is apparently very sensitive to the amount of heat initially used to generate convection, but is not very sensitive to the type of heat source used to initialize convection. When the initial observed wind is altered by using only its north-south component successive cells still occur. The successive formation of new cells is not sensitive to the type of lateral boundary conditions used for calculating normal velocity. Other sensitivity tests are also reported.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD