The Use of a Displaced Radar Dataset to Provide an Authentic Environment for a Radar-based Severe Weather Laboratory Exercise

For roughly the last 5 years, a key component of the annual National Weather Association Severe Storms and Doppler Radar Conference held every spring in Des Moines, Iowa, has been a radar exercise. In the most recent two years, this activity has been used also as a laboratory exercise in a Mesoscale Forecasting Laboratory course at Iowa State University. The activity is created by taking a severe weather event that occurred in one part of the country, and shifting the location to make it appear as though the event occurred in central Iowa. Information on the date is not provided to students. Gibson Ridge Analyst software is used to display the radar data, and allow students to analyze the myriad of products available. The shifting approach involves rewriting the product header of individual Level II NEXRAD files to "move" the data to the DMX (Des Moines) RADAR location and the time of the lab experiment. These files are then locally served via a website to Gibson Ridge Analyst, which believes the data is realtime. The only downside is that there is no way to provide Gibson Ridge a faked RUC2 sounding profile, so hail calculations can be slightly off. Students in the lab course then experience the activity in one half the time it occurred, so that new radar images arrive every 3 minutes instead of 6. Students are tasked with issuing severe thunderstorm and tornado warnings, along with tornado emergencies. To assist with these decisions, storm reports appear on the screen as they are called in to the National Weather Service office, and students also have an overlay of al l population centers. Several verification metrics are computed in real time, and these are projected on a screen at the front of the classroom from time to time. Students can use this information to try to adjust their techniques, for instance, reducing the size of the warnings they issue if their false alarm area metric is too large, or being quicker to issue warnings if their probability of detection is too low. At the end of the exercise, students are asked a series of questions to further evaluate their understanding of the use of radar to diagnose severe weather. Anecdotal evidence suggests that this exercise is extremely popular with the students, and some consider it the highlight of the semester. This is not an easy achievement in a class that has often been cited as a favorite of students, and that also includes a laboratory exercise patterned after a Storm Prediction Center forecaster's shift, and another that simulates a tornado chase.