David Williams
EF4
Hi All,
I had a question about identifying boundary speed. I've been rewatching Rich Thompson's Tornado Forecasting Workshops. In class 6 at 27 mins he zooms in on a hodo and says that he drew in the orientation of the boundary (dryline) with the speed and motion of the boundary measured from observations. If you care to watch the minute of video I'm referring to, I posted the class below (start at 27 minutes and watch for 1 minute). I understand that he has identified the N-S orientation of the dryline and that he knows the storm motion, 0-6 km shear vector, and 9-11 storm relative wind. I also understand that he is identifying these in order to understand whether storms will advance out in front of the boundary into the warm sector, not interact too much with other storms, and possibly stay discrete. However, he doesn't really explain how he determined the boundary speed. As far as I know, there isn't a boundary speed obs page to look at, so my guess is to find the depth of the dryline and look at the wind speeds behind the dryline. Then eyeball if it's actually propagating at that speed. Yet, that seems rife with errors: different heights of the dryline might be moving at different speeds; just because winds behind the dryline are at a certain speed doesn't mean that it will actually move the boundary at that speed because of convergence on the front of the boundary slowing down its forward speed; also the mixing of the dryline creates other difficult and more subtle factors to consider. So, when Rich says "that the speed and motion of the dryline is measured from observations," does anyone know exactly what observations he is referring to? Thanks for any help with this!
I had a question about identifying boundary speed. I've been rewatching Rich Thompson's Tornado Forecasting Workshops. In class 6 at 27 mins he zooms in on a hodo and says that he drew in the orientation of the boundary (dryline) with the speed and motion of the boundary measured from observations. If you care to watch the minute of video I'm referring to, I posted the class below (start at 27 minutes and watch for 1 minute). I understand that he has identified the N-S orientation of the dryline and that he knows the storm motion, 0-6 km shear vector, and 9-11 storm relative wind. I also understand that he is identifying these in order to understand whether storms will advance out in front of the boundary into the warm sector, not interact too much with other storms, and possibly stay discrete. However, he doesn't really explain how he determined the boundary speed. As far as I know, there isn't a boundary speed obs page to look at, so my guess is to find the depth of the dryline and look at the wind speeds behind the dryline. Then eyeball if it's actually propagating at that speed. Yet, that seems rife with errors: different heights of the dryline might be moving at different speeds; just because winds behind the dryline are at a certain speed doesn't mean that it will actually move the boundary at that speed because of convergence on the front of the boundary slowing down its forward speed; also the mixing of the dryline creates other difficult and more subtle factors to consider. So, when Rich says "that the speed and motion of the dryline is measured from observations," does anyone know exactly what observations he is referring to? Thanks for any help with this!
