Severe WX April 4th-6th, 2022 Severe Weather Threat

[Taylor Campbell]

I can see Tuesday could be pretty hairy regarding tornado potential, though shear seems a lot weaker on Wednesday. Nevertheless, I usually don't like seeing CAPE modelled as high as it's supposed to be for Wednesday for GA. I'm not all that good at reading into the details beyond some of the soundings/model data, so are there some particular things that would point to Wednesday being more serious tornado-wise than currently forecast?

The speed and directional shear does look greater Tuesday than Wednesday. However, I think Wednesday still warrants attention for the tornado risk given the amount of instability that could be realized within the 200-250 0-1km SRH and a 40+knt southwesterly LLJ. There's also falling heights and forcing so storm initiation appears likely.

 

[Clancy]

The speed and directional shear does look greater Tuesday than Wednesday. However, I think Wednesday still warrants attention for the tornado risk given the amount of instability that may be realized within the 200-250 0-1km SRH and a 40+knt southwesterly LLJ. There's also falling heights and forcing so storm initiation appears likely.

Gotcha, thanks for explaining!

 

[Austin Dawg]

Great discussion guys. I love when you smarter folks explain things like this for us entry level folks.

 

[tennessee storm chaser]

The speed and directional shear does look greater Tuesday than Wednesday. However, I think Wednesday still warrants attention for the tornado risk given the amount of instability that could be realized within the 200-250 0-1km SRH and a 40+knt southwesterly LLJ. There's also falling heights and forcing so storm initiation appears likely.

Like see the winds just little less veered be honest .

 

[Austin Dawg]

It looks like Texas has been invited to the party again. I hope the enhanced area does not move further south around Austin again. These folks around here don't know what to do when a tornado warning comes out even if it comes out 15 to 20 minutes late.


Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1230 PM CDT Sun Apr 03 2022

Initial storms will likely become supercells --
aided by favorably veering flow with height, and thus potential for
all-hazards severe weather will evolve locally.

With time, storms are expected to cluster together across the
north-central Texas vicinity, with upscale growth likely during the
evening as a strong southerly low-level jet develops. As the jet.
increases/veers, and increasingly strong southwesterlies spread atop
the area, a well-organized -- eventually bowing -- MCS may evolve.
CAM guidance suggests this evolution, which would then shift quickly
east-southeastward across northeastern Texas through the evening and
eventually parts of northern and central Louisiana overnight,
reaching southwestern Mississippi late in the period. As such,
potential for a more widespread wind event is evident, supporting an
upgrade to 30% wind probability/ENH categorical risk. Along with
the wind potential, large hail will be possible locally. Some
tornado risk is also evident -- both with QLCS-type circulations
embedded in the linear convection, as well as with any
isolated/supercell storms which may evolve in advance of the MCS.

 

[Clancy]

Latest NAM 3km run brings some strong instability northward late Tuesday. Worth noting this is occurring behind the big mass of convection earlier in the day.

 

[Taylor Campbell]

NAM is awfully disturbing along with most models in the warm sector Tuesday.

 

[MattPetrulli]

NAM 3k and NAM 12k all go pretty nuclear regarding instability Tuesday/Wednesday (specifically Wednesday considering Tuesday may have recovery problems) and have sufficient shear both days. My question is, how much instability helps make up for the lack of significant wind shear (if that becomes an issue) in terms of significant tornado potential in Southeast?

 

[CheeselandSkies]

NAM 3k and NAM 12k all go pretty nuclear regarding instability Tuesday/Wednesday and have sufficient shear both days. My question is, how much instability helps make up for the lack of significant wind shear (if that becomes an issue) in terms of significant tornado potential in Southeast?

This will be an interesting event to be sure; and kind of an unusual setup for an early spring Dixie event in that it appears CAPE will be a bigger driver than shear (the complete opposite of the last two).

 

[MattPetrulli]

This will be an interesting event to be sure; and kind of an unusual setup for an early spring Dixie event in that it appears CAPE will be a bigger driver than shear (the complete opposite of the last two).

Agreed, Tuesday looks a little more usual for the southeast, I think the main tornado threat will be ahead of any heating infront of the MCS, AL/GA/FL/SC vs behind the MCS where proper recovery may not occur and shear profiles will be worse. Wednesday looks really interesting on NAM, however GFS and Euro are a step below it in terms of thermo and shear. NAM started off really significant for Tuesday then trended worse so that could be the case here. Greatest instability overlap on GFS/Euro do not match up with each other. We'll see as we get closer though.

 

[Taylor Campbell]

The 18z HRRR fires off a string of open warm sector supercells ahead of the MCS and behind the lifting warm front co-located with maximum significant tornado parameters across southeast Alabama, Florida panhandle, southwest Georgia. A lot of times we see this warm sector get hung up along the coast and never make it inland so we just get several tornadic supercells over the Gulf of Mexico that no one hears about. Unfortunately, there appears to be a lot of agreement that this warm front will lift substantially inland and the type of shear/instability coming together over land will all sink in on Tuesday.

 

[KevinH]

I have not seen this thread in a few days.

Based on the SPC outlooks issued this morning, I updated the date of the title from 5-7th to 4-6th. I am smack dab in the middle of the D2 enhanced (Columbus, GA). SMH

 

[xJownage]

12Z NAM 3km wants the MCS to break up in S GA and advects upwards of 3000 CAPE into S MS around 2200Z. It's further south than previous runs, however, limiting the space of the warm sector to mostly southern MS until well after dark. SFC winds are SE which is limiting directional shear, and the environment appears mostly capped, but given sufficient SRH it seems any surface based convection that develops will be pretty dangerous. The HRRR doesn't pick up on this at all.

Whoever said the CAMs getting in range was just going to cause more confusion hit the nail on the head. As the CAMs are coming into range, every solution is wildly different than the last. This is one of the tougher forecasts I've ever tried to make to say the least.

 

[Clancy]

Last frame of the 12Z NAM 3km has a broken up line of storms with UH >75 in an unstable atmosphere. Shear isn't as strong as the lower-res NAM showed yesterday afternoon, however.

 

[xJownage]

Last frame of the 12Z NAM 3km has a broken up line of storms with UH >75 in an unstable atmosphere. Shear isn't as strong as the lower-res NAM showed yesterday afternoon, however.

View attachment 13142

It's also a pretty capped environment. This feels more like a plains setup than a dixie setup, outside of the low level flow being SE.

The flow being parallel to the orientation of the front would favor a linear mode, however, which is something the SPC did mention. Something to keep an eye on.

 

[CheeselandSkies]

HRRR is pretty consistent on some nasty things happening in eastern Georgia into SC tomorrow afternoon. 12Z run also portrays a discrete supercell over Alabama at daybreak.

 

[xJownage]

HRRR is pretty consistent on some nasty things happening in eastern Georgia into SC tomorrow afternoon. 12Z run also portrays a discrete supercell over Alabama at daybreak.

I saw that one discrete cell, but soundings show warm 850s and a surface inversion. Wouldn't that cell be elevated given that environment? There's zero surface cape in that area...

 

[CheeselandSkies]

I saw that one discrete cell, but soundings show warm 850s and a surface inversion. Wouldn't that cell be elevated given that environment? There's zero surface cape in that area...

Yes, I suppose it would be given those conditions.

However, SPC has added hatched tornado area over SE AL, southern GA into far southern SC; perhaps in deference to those HRRR runs among other factors.

 

[Weatherphreak]

So is the consensus a squall line with possible super cells out front across Southern AL, Ga, and FL Tuesday with possibly more scattered storms along the cold front Wednesday over Alabama Georgia Tennessee? Thinking Wednesday would be the bigger threat for points Bham north?

 

[NorthGaWeather]

So is the consensus a squall line with possible super cells out front across Southern AL, Ga, and FL Tuesday with possibly more scattered storms along the cold front Wednesday over Alabama Georgia Tennessee? Thinking Wednesday would be the bigger threat for points Bham north?

As of right now, yes.