A bow echo occurred on 31 May 1998 producing strong winds, hail and tornadoes from South Dakota to Michigan in under 12 hours. The case was modelled using the PSU-NCAR MM% using various boundary layer, microphysics and cumulus parameterizations. The model reproduced salient features similiar to that of observations but did not have the same evolution. Preliminary results indicate that most simulations produced strong ( > 21 m/s ) "surface" winds and developed wake lows,meso-highs and pre-squall lows. Different microphysics produced long lived wake low/gravity wave and another gravity wave ahead of the wake low. When evaporation of precipitation was prevented in the model, the second wave failed to form.