Focus: To understand the microphysical development of precipitation in cloud, including ice and liquid phases and their interactions, and to determine improved methods of representing precipitation formation in very high resolution numerical models.

It is well known that the structure and evolution of precipitating weather systems depend strongly on the microphysics and, in particular, on the conversion of water to ice and vice versa. Such microphysical processes affect the dynamics of systems through their influence on the strength of updrafts, downdrafts, and cold outflows; they also directly affect important forecast parameters such as precipitation type and amount. Quantitative precipitation forecasts, which are a critical societal requirement, are highly sensitive to these microphysical properties and processes. Despite this, precipitation formation processes are currently not adequately represented in both weather and climate models. Especially uncertain is the treatment of water and ice phases and precipitation development. Physically based improvements to the model physics must be developed, particularly for the ice formation that accounts for much of the deficiency.

Subsection of an illustration of rain and ice formation in differing cloud types, altitude/temperatures, and continental or maritime atmospheric conditions. ...more...

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