2018-11-30 Event: AR, LA, OK, TX

Joined
Feb 21, 2012
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Location
Wichita, KS
A bit surprised there isn't already a thread on this event as it appears to be generating a lot of hype elsewhere, and the SPC has already mentioned 10% tornado probabilities with a possible upgrade in the ARKLATEX region.

A nice neg tilted late season trough is ejecting over the southern plains, with ample moisture return and instability for severe weather this late in the year. This should provide a chance for a decent severe weather event in the ARKLATEX region, and potentially farther west if storms can fire along the dryline.

Right now, the most favorable area for tornadoes appears to be where the best combination of instability and SRH resides in SW AR and NE TX, although these will likely be after dark and not in favorable terrain. I am keeping my eye on the dryline as early HRRR indicates a more classic dryline setup, despite not showing storms on the DL. I'm skeptical of the CAMs not showing storms, as subtle surface forcing and a speed max (below) ejects over the dryline late in the afternoon. The GFS and Euro both initiate storms farther west here, however both also exhibit some nasty backing at 500 mb, which would hinder SRH over time and invert hodos.

Overall the setup synoptically has a lot of potential, but also has a lot of things that could go wrong with it, as is typical this late in the year. I work tomorrow but could potentially reach a DFW target if it appears storms will fire on the dryline and provide an opportunity for visible tornadoes. I will not, however, chase the messy storms flying into SW AR after dark.
500wh.conus.png
 
I am curious on potential supercells in central Okla. HRRR has been showing storms firing on the dryline since the 00z run (same with Euro and GFS as Taylor mentioned above). The warm front is currently draped across the I-40 corridor. However, moisture is minimal and relatively shallow via the 12z FWD sounding. But if we can continue to get some moisture advection over the next 5-6 hours I think there is some potential for a tornado if storms do form along the dryline. Low 60 tds seem possible but again it will be a shallow layer.

Here is a sample sounding for OKC at 00Z via the RAP
2018113015_RAP_009_35.45,-97.48_severe_ml.png
 
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