Formation of cirrus clouds, probably the remnants of a former thunderstorm that occurred over Tunisia but which never reached the Maltese Islands. The forecast surface pressure chart was indicating the possibility of a stationary front over the Central Mediterranean and in such case, these clouds could have formed due to upper-level warm air overrunning the colder air at the time. In actual fact, the surface pressure chart on the second thumbnail showed a bad weather line over the Maltese Islands. The first thumbnail shows altocumulus undulatus clouds from the same decaying thunderstorms due to wind shear.