Atmospheric hazards are related to weather phenomena ranging over all atmospheric spatial and time scales. Small-scale events include: tornadoes, hail, lightning, flash floods, etc.; while at larger scales, floods, heat waves, storm surges, wind storms, tropical cyclones etc. are among the most common.

For all weather events producing atmospheric hazards there are conceptual models that can explain the bulk of the physical process, but still leave poorly understood characteristics or anomalies, which can magnify their effects, thus increasing the related risks.

For this reason, to be effective a suited risk management needs high resolution awareness on spatial and temporal frequency and characteristics of atmospheric hazards.

The modeling of the deterministic, but classically unpredictable, evolution of severe weather events has greatly benefitted from the ensemble techniques applied to probabilistic predictions. This approach has contributed in improving the risk management associated with some classes of atmospheric phenomena.

This session encourages contributions devoted to all aspects of "Atmospheric Hazards", and in particular, in line with the theme of the EMS&ECAM 2011 Conference, research results addressing ensemble techniques.

More specifically, this session aims at hosting works dealing with the following phenomena:

1) Extreme cold/heat episodes;
2) Freezing rain and intense snow falls;
3) Severe katabatic or foehn winds;
4) Gap flows;
5) Fog;
6) Breaking of gravity waves;
7) Storm-surges and atmospheric driven marine hazards;
8) Flash-floods and heavy rain events;
9) Hail;
10) Lightning;
11) Tornadoes, waterspouts, derechos and downbursts;
12) Intense Mediterranean cyclones and tropical like cyclones;
13) Tropical cyclones;
14) Local effects of polar lows;
15) Severe wind storms.

We welcome those works dealing with database and data collection related to new ensemble techniques. Contributions dealing with studies of specific episodes (case studies) can find room in this session. Local or large scale studies of atmospheric hazards realized through remote sensing techniques (intrinsically "high resolved", e.g, RADAR, satellite, lightning detection network, etc.) will be particularly appreciated and fostered. Statistical analysis results on severe weather phenomena and related damages are of great interest for the atmospheric hazards session too.