Evaluation of WRF forecasts of tornadic and nontornadic outbreaks when initialized with synoptic scale input
Chad M. Shafer, Univ. of Oklahoma, Norman, OK; and A. E. Mercer, L. M. Leslie, M. B. Richman, and C. A. Doswell
A primary goal of this project has been to determine the degree to which the synoptic scale influences severe weather outbreaks. In this study, the Weather Research and Forecasting (WRF) model is used to forecast 50 tornado outbreaks and 50 severe thunderstorm outbreaks using the NCEP Reanalysis dataset as input. Forecasts are conducted over a 24-hour, 48-hour, and 72-hour period.
The overall quality of these forecasts strongly suggests that the synoptic scale has a substantial impact on the type and severity of severe weather outbreaks. Forecast skill is impressive for 24-hour forecasts; the WRF frequently forecasts the synoptic and sub-synoptic environment and the coverage and severity of convection very well. Forecast quality notably degrades with 48- and 72-hour forecasts, but the WRF still predicts many of these events quite well. Finally, the WRF appears to be distinguishing the type of severe weather outbreak correctly in many cases, especially with 24-hour forecasts.
A summary of the WRF's forecast quality with these cases will be shown using subjective analysis and verification statistics. A comprehensive diagnosis of some of the more notable cases will be done to describe the methods used to evaluate these forecasts. Trends in forecast quality and behavior will be discussed. Potential variables to discriminate between the type of outbreak will be emphasized.
Session 4A, Applications in Meteorology, Oceanography, Hydrology and Climatology - Part I
Tuesday, 22 January 2008, 11:00 AM-12:00 PM, 206
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