Several thunderstorms formed in northern Oklahoma this afternoon and merged to form a bow echo, which is moving off to the southeast at about 40 MPH. As of 830 PM CDT, the leading edge of the line was running down the length of the Arkansas River just southeast of Cleveland OK.
I'll update this diary as a standard Severe Weather Liveblog. Check back frequently. Latest updates will appear at the top of the text below the squiggle.
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Here's the initial radar as of 830 PM CDT. Severe thunderstorm warnings are yellow boxes, tornado warnings are red boxes.
Update 3: Thankfully, this line of storms has weakened below severe limits. I won't update this diary again unless they regenerate, or a big metro area goes under a tornado warning.
Update 2: Here's the latest radar from Tulsa, at 916PM CDT. The warning box disappeared because it expired at 915, and I'm not sure if they're going to reissue it or not. Seems like the wind died way down in the storm over the last half hour, which is a good thing. Leading edge of the storms have reached downtown Tulsa.
And for the hell of it, here's a 3D image of the storms at around 906PM CDT, looking southwest with Tulsa in the middle of the box. The arrow denotes the way in which the storms are moving.
Update 1: Here's the latest radar from Tulsa, at 843PM CDT. I've illustrated the rotation on the radar, the general movement of the rotation, and where it is in relation to Tulsa (at the very bottom of the image). This happens frequently in stronger bow echoes.
These storms have a strong jet of air punching in from behind them, and it makes certain parts of the storm move faster than the area surrounding it. This creates rotation and can spin up quick tornadoes. Think of it like running your hand through bathwater or a swimming pool...all the little vorticies that show up at the edge of your hand is similar to what's happening now.
Here's a zoomed in view of the northwestern Tulsa area. The first is the base reflectivity (precipitation), and the second is the base velocity (winds in knots). For reference, this bow echo is generally moving to the East-Southeast at 35 knots (40 MPH).