Cold-season precipitation bands—radar structure and particle growth mechanisms

The Profiling Of Winter Storms (PLOWS) field project took place in the 2009 and 2010 winters to study the structure of mid-latitude cyclones in the central United States. Intensive observations were made of cyclones and embedded features such as precipitation bands, resulting in a large set of airborne and ground-based radar observations and in situ microphysical measurements documenting these structures at very high resolution.

Radar reflectivity and vertical air velocity were measured by the University of Wyoming Cloud Radar (aboard the National Center for Atmospheric Research C-130 aircraft) as well as from a ground-based X-band profiling radar. In situ microphysical measurements, in conjunction with these radar measurements, are used here to describe the structural characteristics of banded precipitation features. We focus particularly on precipitation bands developing at the interface between the mid-tropospheric dry slot and the moist airstream to its north and east. We compare these with those occurring further within the moist airstream. Our analyses focus on ice particle growth mechanisms associated with precipitation banding and their relationship to the observed radar reflectivity enhancement characteristic of these features. Analyses will concentrate primarily on the cyclone observed on 14-15 February 2010, although results will be briefly presented from other PLOWS cases.