Does anyone know if the volcanic ashcloud 23 may 2011,will affect flights from Prague to jhb 24 may?

a family member of mine is flying back from prague on the 24 May 2011, to arrive in jhb on 25 may. she is flying via Paris. i know that the ash cloud is affecting the uk and europe slightly. does anyone have more information on this? as i would like to know if her flight could be cancelled. The airline website doesnt have any information. any help would be greatly appreciated.Thanks