Severe WX Severe Weather Threat 3/14-3/16

[Grand Poo Bah]

Energy helicity index values up to 8 in a large area now on the NAM, here’s a sounding taken in central Mississippi 4pm.

First time I’m seeing helicity values this high regarding the setup, this combined with 2000+ cape values it’s no surprise the hodograph looks like that.
View attachment 35248

600 helicity... That's crazy... Same helicity, same sheer, same D cape, as the other one now. Here's hoping the now apparent lack of MUCAPE is the secret ingredient that will cause the storms to collapse under their own strength. Maybe only 2000 CAPE for a system like this is like putting 89 octane gas in a jet engine.

 

[CheeselandSkies]

Remember when moisture depth was a limiting factor? Because it sure isn't now.

That was really only ever for Friday, particularly with northward extent, which is still true to some degree. Without the moisture issues we could be looking at a higher-end tornado threat across IA/IL/MO perhaps similar to 3/31/23.

 

[jiharris0220]

600 helicity... That's crazy... Same helicity, same sheer, same D cape, as the other one now. Here's hoping the now apparent lack of MUCAPE is the secret ingredient that will cause the storms to collapse under their own strength. Maybe only 2000 CAPE for a system like this is like putting 89 octane gas in a jet engine.

“lack of MUCAPE is the secret ingredient that will cause the storms to collapse under their own strength”

That’s not how that works, unfortunately.

What would cause storms to “collapse under their own strength” would be abundant mid level dry air, insufficient mid level lapse rates, or if the cape over shear ration (leaning towards shear) is too high, combined with weak forcing that any convection would get sheared apart.

None of this looks likely at all at the moment in any modeling.

Also, I’m not seeing any lack of most unstable cape, 2000+ is far more than enough to sustain supercells in Dixie valley

 

[tennessee storm chaser]

That was really only ever for Friday, particularly with northward extent, which is still true to some degree. Without the moisture issues we could be looking at a higher-end tornado threat across IA/IL/MO perhaps similar to 3/31/23.

Nam model has picked up on creeping it further north each run. Is it right. ?

 

[OhOkayThen]

Friday night looks interesting further East now. WRF-F3 is trying to break up the line once it gets past the Mississippi River and get some discrete supercells going. So much at play Friday and Saturday.

 

[MichelleH]

True. I only know a handful of people who have basements. I didn't when I lived in my old house.

When my son and I bought a house together two years ago, a basement was a make or break condition for me.

 

[CheeselandSkies]

NAM definitely continues to be aggressive with moisture return into AR/southern MO and perhaps further north on Friday. And keep in mind that 69 degree temperature likely reflects its cool bias. Low-level CAPE would be even greater in that case.

 

[Kds86z]

When my son and I bought a house together two years ago, a basement was a make or break condition for me.

Don’t blame you at all after 4/27…

 

[Equus]

Grandparents' house here next to my tiny house thingy luckily has a basement and even a little nook behind an unfinished section that even would protect against the house collapsing into the basement, already planning on putting some essentials down there and cleaning it out for Saturday

 

[MichelleH]

Don’t blame you at all after 4/27…

Yes, we were in Hanceville at that time and the morning EF2 got too close for comfort. We were lucky but we heard it.

 

[Brice W]

Yes, we were in Hanceville at that time and the morning EF2 got too close for comfort. We were lucky but we heard it.

Yikes that’s horrifying, did you get any glimpses of the wall cloud or what it looked like?

 

[jiharris0220]

Here’s the full run from Brady’s MMFS model for anyone curious.

 

[Kds86z]

Here’s the full run from Brady’s MMFS model for anyone curious.

…..

 

[Thanksgivingbrown]

Here’s the full run from Brady’s MMFS model for anyone curious.

Monster right over Huntsville. Gross

 

[TornadoFan]

Here’s the full run from Brady’s MMFS model for anyone curious.

 

[Grand Poo Bah]

“lack of MUCAPE is the secret ingredient that will cause the storms to collapse under their own strength”

That’s not how that works, unfortunately.

What would cause storms to “collapse under their own strength” would be abundant mid level dry air, insufficient mid level lapse rates, or if the cape over shear ration (leaning towards shear) is too high, combined with weak forcing that any convection would get sheared apart.

None of this looks likely at all at the moment in any modeling.

Also, I’m not seeing any lack of most unstable cape, 2000+ is far more than enough to sustain supercells in Dixie valley

I'm for sure just trying to find some hopium for what is looking like an absolute historic tornado outbreak. 2000 CAPE is absolutely plenty to support strong tornadoes. It just feels too early in the year for those values to stay high as the storms progress... Well, it would be if the low pressure system wasn't sucking unstable air straight off the Gulf of Mexico and feeding itself like the hungry little monster that it is...

What is the analog from that sounding?

Edit: woah, glitched out comment. Sorry about that

 

[Brice W]

Here’s the full run from Brady’s MMFS model for anyone curious.

So that’s not…

 

[Maxis_s]

?????

 

[wx_guy]

For those not paying attention, the parameter space modeled by the models somehow, unfathomably, continues to uptrend. It's now in such a rarified space that there almost ARE no analogs that fit (for instance, 700 SRH and 8+ STP with EHI of 10+ and LCL basically on the ground is just ludicrous). I know every setup and system is different with its own flavors and whatnot. But we should at least consider the distinct possibility that this event could (IF parameters are realized) hug up against the big 'ol boys, if you know what I mean...

 

[TornadoFan]

Well....that's suboptimal.