Sunday, May 23, 2010

Can You Find the Tornado?

A big hello to all 25 of our followers and anyone else who may be reading this! I'm always a bit unsure of what you all may be interested in reading about from VORTEX2, so I'm going to shamelessly attempt to run up my comment total by asking anyone with specific questions or suggestions for posts to let me know and I'll try my best to answer them in subsequent postings.

In the meantime, I will just share a few images the TTUKa radars have captured in the past week. The above image does have a tornado in it, which occurred to the northwest of Kingfisher, OK on May 19th, but it's not easy to tell at first glance. The image is a range-height indicator scan (which is a vertical slice through the storm) with reflectivity on the left and radial velocity on the right. The tornado is the area of lower reflectivities (green colors) near the lower center of the left panel. For this image, we were scanning the westward edge of the tornado from the south, so the winds are blowing towards the radar (cooler colors in the velocity image). The reason for the large area of orange colors within the tornado in the velocity image is that the wind speed is too high for the radar to unambiguously sample. So, once the velocity passes a certain wind speed it "folds" to the opposite end of the color scale, like Pac-Man wrapping around to the opposite side of the screen. So, backing out the actual velocity, we estimate wind speeds of upwards of 50 m/s or just over 100 mph, and we likely didn't sample the highest wind speeds in this tornado!

Ok, the second one is a bit easier, especially if you've read my last post. This image is a near-surface PPI (horizontal plane) scan taken by TTUKa-2 of a weak tornado east of Dumas, Texas on May 18th. One of the cool things about this tornado is that it did not occur in the mesocyclone, but along the rear-flank downdraft boundary (RFDB). This storm exhibited many strong circulations along the RFDB that we could watch wrap back into the mesocyclone. As circulations like this have been theorized to contribute to tornadogenesis, capturing their evolution with our radars is a very exciting finding.

Finally, this third image is not of a tornado, ... I think. This is a close-up image of the very tip of the hook of the Dumas supercell. So, when you look at a hook echo from a standard radar, the big red reflectivity ball in this image would be roughly representative of the trailing one or two pixels. All of the tip of the hook in this image is within five kilometers of the radar and TTUKa-2 was set up about 3 miles to the east, scanning the same mesocyclone. This means that we can conduct a dual-Doppler synthesis of this event and derive the full three-dimensional wind field of the near-surface mesocyclone! (this is the kind of nerdy sentence we meteorologists like to put exclamation points at the end of). So some lucky graduate student (possibly me I guess) will get to spend countless hours sorting through the fine-scale details of this case trying to make sense of it. Woohoo!

Well, we're headed to bed tonight in a state that starts with the letter "K" and should be operating again tomorrow, most likely on a road somewhere. I do want to mention that I've run the bird total up to nearly 50. Highlights include three life birds for me, a Cassin's Sparrow and Scott's Oriole just north of Carlsbad, NM, and several Clarke's Grebes in North Platte, NE yesterday.

Finally, finally, one last image, of the Kelvin-Helmholtz instability waves propagating vertically I mentioned in my last posting:

1 comment:

  1. I really enjoyed seeing the pictures and reading the explanations. Good luck with your last couple of weeks. Hope you find the right storm at the right time and get the data you're working so hard to find.