Based on economic considerations, extreme snowload situations occuring just infrequently are not included in the standards. In parts of the alpine region and the Bavarian Forest the factual snowload during the winter season of 2005/2006 as specified in the standards (and therefore also in DIN 1055-5: 1975-06) exceeded its presumpted load, then beeing established by German building authorities, by far. As a consequence, roofs had to be cleared from snow in order to prevent building collapses. It clearly appeared that often roof snowloads were not payed its due attention.
As opposed to information about avalanche situations, qualified information for house owners and construction experts about current snowloads are supplied neither by building control authorities nor weather services, even if local standards are exceeded in large scale.
snowload according to norm:
calculate snowload according to DIN 1055 (in German)
Information about snowload in Austria (in German)
THW OV Witten, snowload measurement (in German)