Ensemble Kalman filter analyses and forecasts of a severe mesoscale convective system observed during BAMEX

A WRF-based ensemble data assimilation system is used to produce storm-scale analyses and forecasts of the 4-5 July 2003 severe mesoscale convective system (MCS) over Indiana and Ohio, which produced numerous high wind reports across the two states and contributed to significant flooding across central Indiana. Single-Doppler observations are assimilated into a 50-member, storm-scale ensemble during the developing stage of the MCS with the ensemble Kalman filter (EnKF) approach encoded in the Data Assimilation Research Testbed (DART). The storm-scale ensemble is constructed from mesoscale EnKF analyses produced from the assimilation of routinely available observations from land and marine stations, rawinsondes, and aircraft, in an attempt to better represent the complex mesoscale environment for this event. The current study seeks to expand upon previous work with a storm-scale EnKF, which has been more focused on isolated supercell thunderstorms, by considering any issues that may be unique to meso-convective organization.

Given the particular sensitivity of the studied system to prior convection (and remnant cold pools), preliminary work will evaluate the impact on EnKF analyses/forecasts of assimilating research quality data—in addition to conventional meteorological observations—from dropsondes and temporally high-resolution surface meteorological sites. In each experiment, comparing the temperature characteristics of simulated cold pools to available observations will assess the accuracy of thermodynamic retrievals by the EnKF.