11th Conference on Atmospheric Radiation and the 11th Conference on Cloud Physics

Monday, 3 June 2002
A Correlation of Snow Crystal Phenomenology to Radar Patterns and Lightning Activity in Winter Storms
Peter Benjamin Roohr, CIRA/Colorado State Univ., Fort Collins, CO; and T. H. Vonder Haar
Overall, very little research has addressed the phenomenology of snowflakes in the convective regions of winter storms. Snowflakes can reveal the temperatures and liquid water contents in the central regions of winter storms that contain electrical activity, whether it is represented by intracloud or cloud-to-ground lightning, or just very high electrical fields. Comparing snowflake types to lightning activity and returns from dual polarized radar would reveal interesting physical connections that occur inside of a convective winter storm and lead to high snow accumulation rates.

Volunteer observations of snowflake type during the Winter Icing and Storms Project (WISP) of 1990 and 1994 enabled the analysis of snow characteristics along the northern Front Range of Colorado’s Rocky Mountains. Two winter storms were analyzed, to include the Feb 11-12, 1994 arctic front system, and the large, well stacked Mar 5-7, 1990 storm system. Dual polarized radar data from the CSU-CHILL (Colorado State University Chicago Illinois) Radar were collected and analyzed for the 1994 system, while lightning data were collected and analyzed for both systems. For both systems graupel was found in the area of the convective activity as defined by radar and lightning data. Graupel is a key ingredient in the formation of electrical activity in storms, and usually falls in heavy snow situations, whether they be short-lived or long in duratio

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