The simulations were executed using 5.5-day overlapping run segments on an eastern U.S. grid (Fig. 1) with 12-km horizontal spacing and 34 vertical levels, extending from the surface to the 50-hPA level. All WRF– ARW, version 3.0, andMM5, version 3.7, simulations were configured on a similar (MM5 has an Arakawa B grid while WRF is on an Arakawa C grid) horizontal grid and the same vertical sigma levels.