Abstract
On 7 May 1985 a mesoscale convective system (MCS) developed within a moderately forced large-scale environment for upward motion and moved into the observing network of the Oklahoma-Kansas Preliminary Regional Experiment for STORM (PRE-STORM). The initial region of convective development occurred out-side the PRE-STORM network in a data-sparse area. Simulations using The Pennsylvania State University—National Center for Atmospheric Research (PSU-NCAR) Mesoscale Model are produced using initial conditions from two different initialization techniques, static initialization and improved dynamic initialization, to evaluate the ability of the mesoscale model to reproduce the complex evolution and structure of this MCS. The results indicate that, even when including the special PRE-STORM data in the model initialization process, the numerical simulation that uses the initial condition from the static initialization fails to simulate the observed evolution of the 7 May 1985 MCS. This is attributed to both the relatively weak large-scale forcing for upward motion and the lack of adequate mesoscale observations of the low-level moisture distribution and wind field in the Texas panhandle and western Oklahoma. In contrast, the initial condition from the dynamic initialization approach that uses the results of a continuous four-dimensional data-assimilation technique (nudging) as a first guess for a static initialization (both of which include the special PRE-STORM data) produces a successful simulation of the MCS. This simulation captures remarkably well many of the observed and analyzed mesoscale features determined from the high-resolution PRE-STORM observing network data. Threat scores for precipitation amounts and root-mean-square errors of sea level pressure are calculated to provide an objective measure of the quality of the simulations.
