Tuesday, 12 August 2003: 9:00 AM
The Use of Polarimetric Radar Data in the Winter Weather Warning Decision Making Process: A Case Study
A winter storm affected parts of southern Oklahoma during the afternoon and evening hours of 24 February 2003. Snow was the primary precipitation type produced by this winter storm in the affected areas of southern Oklahoma, with a 30-mile wide area where amounts were in excess of 10 cm (4 in), and maximum amounts exceeded 20 cm (8 in). However, during the onset of precipitation across southern Oklahoma, between 2000 and 2300 UTC 24 February, a significant amount of mixed precipitation was reported. The combination of mixed precipitation reports, and observed and model forecast thermodynamic profiles that were not clear on dominant precipitation type during the event, resulted in low confidence forecasts of accumulations of ice, sleet and snow. Between 2300 UTC 24 February and 0000 UTC 25 February, precipitation type changed to heavy snow, resulting in significantly higher accumulations than initially forecasted. Despite some sampling limitations due to range, real-time evaluation of polarimetric radar data from the KOUN WSR-88D was quite helpful to forecasters in detecting the mixed precipitation early in the event, and in detecting the change in precipitation type to heavy snow. Most importantly, polarimetric radar data significantly increased forecaster confidence in the widespread nature of heavy snowfall once the change to snow occurred. Thus, forecaster confidence in upgrading from a winter weather advisory to a heavy snow warning was greatly increased.