2019-03-09 EVENT: KS/OK/TX/MO/AR/LA/IL/KY/TN/MS/AL

[MikeD]

Saturday will bring an upper trough into the Midwest This could go either way. If we have high CAPE, we could have a super outbreak, but that doesn’t seem the case from five days out. Upper atmosphere looks EXTREMELY good, speed shear >100 KTS at 33,000 ft. Also good shear at low levels, at 4,800 ft we have 50kts. The directional shear is almost ideal at low levels.

 

[Jeff House]

Agree with above. Data today hodographs generally still look good, gentle turning shape vs any strange kinks. Couple model runs had 700 mb wind speeds a little lower than above/below; but no strange direction is noted. (Note I checked more Dixie than Plains.)

Interesting how strong the low to mid-levels are otherwise (again). Storm motion should be fast. The next question will be instability. Euro had a run or two quite robust, but it's not consistent. GFS generally has less CAPE. NAM just out to 84 hours is robust on instability and kinematics. We'll see if that's accurate, or just NAM nuts.

Pattern recognition and numerical models show a lifting warm front. Pre-frontal trough or quasi dry line is forecast moving through Arkansas ahead of the cold front. To chase I'd want a chance of slower moving boundary rider(s). I'd look for pre-frontal trough and warm front intersection. If morning rain deposits an outflow boundary, weigh it vs the warm front (still with pre-front trough).

I sat out the first two Dixie events. If the meteorological chase target lines up with decent terrain (the flat Delta) this one might be worth a try. However the instability needs to work out.

 

[Ethan Schisler]

Watching 2 areas tomorrow for potential chasing. First area is Southern IL along the warm front. I don't really feel like driving down to MS/TN and I think the warm front holds better potential due to backing winds out of the SE. Second area is across Eastern/Northeast MO into Southwest IL just ahead of the low pressure system, if we can get enough moisture and instability. Both targets are highly contingent on morning convection and whether moisture/instability can make it up here or not. The further north target seems to have higher 0-3km CAPE values than further south, which appeals to me quite a bit along with strong deep layer shear and ESRH values near 400m2/s2. Critical angles in both areas aren't where I'd like to see them (somewhere each side of 90 degrees), so I'm not sure how this will play into any tornadic potential. Also with the northern target, I'm concerned the best forcing will be further east by that time and storms may not fire on/ahead of the low. Will wake up early tomorrow morning and decide what to do, either way only looking at a 5 hour drive at furthest.

 

[Devin Pitts]

It seems like the models have begun picking up on the trough slowing down, which is pushing me towards throwing my hat in and chasing this event. That 12z HRRR run this morning got me all excited for Cold Core potential in Western IL, but I'm pretty skeptical of it at the moment and the 18z HRRR did calm down a bit on that front. As of now I'm looking at targeting the warm front down in Southern IL tomorrow if it looks like it's going to be north of the forests. The 0-3km CAPE that's been showing up on the models is pretty incredible and I can imagine storms doing fun things with it.

Although If that dry slot that is being advertised by the RAP and HRRR does show up I'd be hard pressed to not gun for the Cold Core target seeing that it will have somewhat more manageable storm motions and would benefit from its proximity to the low. Being based in central IL, either target is not too far for me thankfully so I can hold off on leaving for a bit until I'm sure of things.

 

[Jeff House]

Once again I did not chase within 3-4 hours of CHA. However I watched Saturday closely.

Late morning I noticed a differential heating boundary (east-west) through North Mississippi and North Alabama. Rain fell north of it Friday and thundershowers move along it Saturday morning. Visible satellite showed a sharp line between overcast and 50/50 skies. Temp/dew north was 60-ish/50s and south 70s/60s. Wind shift was very subtle; so, I call it differential heating. However it later behaved like any outflow boundary...

Few CAMs picked up on a threat in MS/AL/southern TN over the West Kentucky (synoptic) triple point. Synoptic trough extended south into Arkansas, where a couple morning tornadoes occurred. When Arkansas trough approached the lifting MS/AL/TN boundary (mid-late afternoon) surface winds backed ever so slightly on some of those CAMs (which verified). SPC picked up on the Deep South over West KY. Conceptual model also has locally higher helicity along the lifting east-west boundary esp. near the intersection with the trough (MS/AL/TN). Brief tornado touched down near Savannah, TN along lifting east-west boundary into Tenn. Couple more touched down in North Mississippi, approaching Alabama.

Couple local/regional Dixie chasers documented Arkansas and Mississippi tornadoes. More related to Storm Track, and cold core fun, congratulations to those farther north / Midwest in the Reports thread!