Analysis of the June 11, 2001 Wisconsin Bow Echo and Associated Rear-Inflow Jet & ‘Bookend’ Vortex

Presented is a synoptic and mesoscale analysis of the June 11-12, 2001 bow echo storm event. The storm system originated in southern and central Minnesota during the afternoon hours of June 11, 2001, and spawned several tornadic supercells. The storms moved to the southeast into northwestern Wisconsin where the mesoscale convective system (MCS) gradually developed a line of intense radar reflectivity oriented from the southwest to the northeast. The storm was further enhanced as the MCS outflow became part of a dynamic flywheel associated with a 250 hPa jet located to the northeast of Wisconsin. At approximately 0100 UTC on June 12, 2001, the line of storms began to develop a bowed structure in the radar reflectivity known as a bow echo. Over the next four hours, this bow echo was further enhanced by a strong rear-inflow jet. The intense system-scale downdraft associated with this MCS created a severe straight-line wind storm called a derecho spawning wind gusts in excess of 70mph. _______________________________________________