Figure 13.  The schematic (lower left) of a classic line echo wave pattern (LEWP) is borrowed from Fujita.  Above are KDGX 0.5 degree reflectivity and storm relative velocity data from the first MCS as the system entered west Mississippi. Three HP supercells that  make up the LEWP are denoted by yellow arrows. is the U.S. government's official web portal to all federal, state and local government web resources and services.