2012-05-24 MISC: NE

[Ryan Pfeifer]

http://www.ketv.com/news/local-news...e-Co/-/9674510/14161406/-/e97u6h/-/index.html

Anyone have any thoughts on how we get a tornado capable of that level of damage in the conditions that were present? (For starters: Temp ~ 70. Dew ~ 50. Surface winds out of the north but outflow from storm to the south could have maybe reversed that I suppose. Storm motion to the E) I wish I had more time right now to look more into it myself.

EDIT: Shoot, could the title be changed to the correct date? 2012-05-24

 

[Andy Jackson]

Missed that, I saw about 500jkg of cape coupled with cool air aloft/high vorticity. I guess cold core can be behind the front as well...wow amazing.

 

[Terrence Cook]

When i saw the warning and text suggesting a long event, i was blown away. Considering the outlook area yesterday and the parameters at play in C. NE... Talk about the endless challenges of forecasting a chase on these Great Plains. Simply stunning considering the 'near' complete bust in Wisconsin.

 

[Jesse Risley]

I think you can look to the nearby OAX sounding at 00z for clues here: http://www.spc.noaa.gov/exper/soundings/12052500_OBS/OAX.gif

I hadn't looked at the environment much prior to this morning, as I was playing out ahead of the front in NE MO, but going back over the past 36 hours of data, there was ongoing convection in that region early Thursday. I'm guessing that this convection probably set down a boundary that is difficult to discern using limited surface observations across the region. The area was able to modestly recover, per satellite trends from yesterday afternoon, along with the Skew-t/Log-P analysis showing 475 J/KG of surface based CAPE and fairly steep low-level lapse rates of 7.7 C/KM.

The upper-air disturbance had apparently been generating scattered thunderstorms over the sand hills region of NW NE early yesterday afternoon, per radar loops early Thursday afternoon, and those storms worked east as the best forcing for ascent moved E/NE. At 500 mb, note that at 00z, close to the time of the tornado, that area was on the left quadrant of 65kt mid-level flow with cool H5 temperatures AOB -16C working into the region: http://www.spc.noaa.gov/obswx/maps/500_120525_00.gif

A glance at 23z LCLs on the mesoanalysis archives also noted that the region lied on the northern edge of a lower LCL gradient, with much higher LCLs residing just south of I-80, depicting a pretty sharp ridge of dry air just to the south (this is quite evident on the 00z/25 TOP Skew-T/Log-p diagram).

While not exactly the most textbook cold core setup per se, the cold air aloft atop the recovered airmass resulted in the classic setup for enhanced stretching in the lower levels given adequate surface bouyancy, and an old OFB may have provided some enhanced streamwise vorticity at the surface such that when those storms propagating out of the sand hills interacted with the boundary, the brief, albeit respectable tornado occurred in an otherwise "sleeper" environment.