Sudden Storm Commencement (SSC) is the first stage of a geomagnetic storm. It usually appears as a sudden positive spike in the SYM-H or Dst index, caused by a hydromagnetic shock from the solar wind. This effect is normally seen as a positive increase in the H-component of the magnetic field at most low-, mid-, and sub-auroral latitude stations worldwide. However, during the Mother’s Day geomagnetic storm of May 2024, we observed an unusual positive signature in the H-component at certain stations located just to the west of the line or longitude passing through the subsolar point on the sunlit side of Earth. Further analysis shows that this is not a very rare event—it happens several times during strong geomagnetic storms with intense substorm activity. Our investigation suggests that this strange reversal occurs because of the way compressional hydromagnetic waves interact with localized ionospheric currents generated by intense auroral activity that travel equatorward. As the DP2 current system forms two vortices flowing in opposite directions, the incoming hydromagnetic shock strengthens these currents differently on each side of the above-mentioned line passing through the subsolar point. This creates opposite magnetic signatures at stations in different longitudinal positions.