A high-density structure under northward interplanetary magnetic field BZ conditions is identified at the Wind and IMP 8 satellites, both in the solar wind on August 22, 1995. A compression of the magnetosphere is observed by the GOES 7 magnetometer within a few minutes of the pressure increase encountering the magnetopause. The response of the high-latitude ionosphere is analyzed on the basis of ground-based magnetometer data. A comprehensive description of this response in the Northern Hemisphere is provided by more than 70 ground magnetometers. This data set is interpreted in terms of high-latitude ionospheric potential patterns by means of the assimilative mapping of ionospheric electrodynamics technique. Convection cells in the polar cap are formed and disappear on minute timescales in accordance with previous results. However, the high-latitude ionospheric ground magnetic signature does not match the interpretation as events of traveling convection vortices, as has been suggested by past studies. ¿ 2000 American Geophysical Union