March 14-15 Severe Weather Outbreak

[Brian D]

A little solo to start the blood pumpin for the active day. This particular solo turned out well mixed with the symphony accompaniment. 

 

[Powerball]

Storms are already on the verge of erupting in Eastern OK/KS, with plenty of clear skies ahead of it.

[Jackstraw]

Storms moving at 50-60mph lol. Good luck if your chasing....or running lol.

[SchaumburgStormer]

Nothing like a long track, violent tornado, cruising at highway speed, potentially after dark, to cause some issues. 

[A-L-E-K]

rip stl

[sbnwx85]

Gonna straighten out that Arch.

[Powerball]

[nvck]

https://x.com/CameronJNixon/status/1900567103628857486

excellent thread by cameron nixon on why this storm mode may be more supportive of long-track tors than a purely supercellular one

IMO, this could be cause enough for a high risk at 1630z

[pen_artist]

Will get new outlook in a little over 35 minutes so we shall see. For those interested, Convective Chronicles just added new video highlighting the threats.

 

[nrgjeff]

If chasing it's a good idea to pick a side of the Mississippi River (or Missouri River, any river) and stick to it. Don't get into a safety jam because of the River. Always have TWO escape routes. I like east and south. River typically cuts off one, but I can't accept that. So, chase is done before the river. Otherwise one can wait on the Illinois side (other side of whatever river) and let the storms come. Better yet, stay home and enjoy college basketball.

[nvck]

HREF with a UH bullseye around and north of STL tonight.

[Stebo]

I am very concerned with STL's metro this evening. Moisture arrives just in time to make this a very significant potential.

[OHweather]

There will probably be a shit load of tornadoes from central and eastern MO into western and central IL, with the threat for stronger tornadoes probably maximized in the vicinity of St Louis later this evening. There will also be a ton of straight-line wind damage. A secondary threat for potentially stronger tornadoes is evident from MS into northern/western AL as well later this afternoon/evening.

Pretty impressive model agreement on either a line, or a mixed arc of bowing segments and some embedded semi-discrete supercells evolving from MO into IA and IL this afternoon and evening, with some tendency for more cells towards the southern end of that. Some models keep this activity semi-discrete (or at least maintain decent line breaks) through much of the evening, especially into central/southern IL. This activity will be extremely strongly forced. Most CAMS other than the 3km NAM have a cluster of more weakly-forced convection developing from eastern AR/LA into MS and western/northern AL. Evolutions vary a bit more with that activity, likely due to weaker forcing. There likely will be a relative minimum in severe/tornado potential centered on western TN between these two areas, though some models have more isolated activity trying to play out even there. 

3km NAM:

HRRR:

ARW:

NSSL:

 

They look slightly different but all agree on the overall evolution in both regimes fairly well (sans the NAM in Dixie today). No model is handling the current elevated convection great, though after 20z I kind of like the HRRR's and NSSL's reflectivity and overall evolution just a bit more than some others. 

You can get the idea that the northern activity in MO/IA/IL is much more strongly forced than the Dixie activity today:

Something to keep in mind, the 500-700mb jet doesn't really punch into the warm sector in the upper Mississippi Valley until after 0z...so, shear profiles will already be impressive this afternoon and will improve markedly after 0z...500mb:

700mb (which is roughly 3km, so think of your 0-3km bulk shear vector for bowing segments and mesovort tornado potential, along with your 0-3km SRH). Low-level shear will be strong in the warm sector this afternoon and explode starting right around 0z this evening:

Activity in the Deep South will be driven largely by a rich low-level jet, though even some of that lifts into the upper Mississippi Valley after 0z:

The strong forcing argues for quick upscale growth in MO, IA, and IL this afternoon and evening, and most of the CAMs above do have a more linear mode than cellular. However, most do have hints of a more semi-discrete mode from east-central MO across central/southern IL and perhaps into far west-central IN. It is in this area where for several hours after 0z the bulk shear vectors are oriented 30-45 degrees across the expected convective line, which does argue for right-moving cells. The forcing is also a bit weaker farther south, which could assist in maintaining a somewhat more discrete mode:

Some maybe representative soundings...from North Central MO late this afternoon:

The shear is quite strong and the thermodynamics are sufficient for severe weather and not prohibitive for tornadoes...however, the thermodynamics could be better and the low-level flow is fairly unidirectional. 

East-central MO later this evening:

While the low-levels aren't extremely unstable they're unstable enough, with 1500 J/KG of MLCAPE being fully sufficient for significant severe weather and tornadoes. The low-level flow could still be more backed (and may locally back more than this), though even without it the increased low-level shear after 0z increases effective SRH notably. Any bowing segments in this environment would be capable of swaths of sig wind damage and tornadoes as well...however, the main concern is if semi-discrete cells interact with this environment as some signs point to. Strong tornado potential is evident, though there are subtle limitations which may keep the ceiling for this event from blowing into the stratosphere. 

Here's a look at a sounding in central Mississippi this evening:

Upon clicking around several of these soundings to find representative ones, I found the low-level shear to be best in the Deep South. However, the low-level lapse rates are quite weak with richly moist low-levels. That could be a limiting factor for greater tornado potential...however, the fact that most CAMs have discrete or semi-discrete cells playing out in this environment suggests tornado (potentially strong) potential, even if there are limitations. 

Overall, I would suggest patience. Storms will probably be severe with scattered to numerous straight-line wind reports, scattered hail, and a few tornadoes this afternoon in MO/southern IA...the northern threat likely maximizes starting around 0z, with potential for somewhat more discrete activity on the southern edge of that from east-central MO into central/southern IL. The environment this evening will support widespread/significant wind damage with any bows, along with QLCS tornadoes, with any supercells capable of all hazards including strong tornadoes. The tornado threat will gradually decrease with northern/eastern extent into IA, northern IL, southwest MI and across IN, though given the strong low-level shear QLCS tornadoes can't be ruled out where any surface-based CAPE persists overnight, assuming some organized convection can persist. There may be a relative min in severe coverage in the vicinity of western TN, with a secondary threat area focused on MS and western/northern AL. This southern threat area has tornado (potentially strong) potential, but with some overall limitations. 

I think east-central MO into central/southern IL has the greatest severe wx and intense tornado potential overall today and tonight, though there is a much broader area with severe/some tornado potential across MO/IA/IL/southern WI/southwest MI/IN. I could see the coverage of tornadoes and EF-2+ verifying a small 30% hatched area in practically perfect verification in the MO/IL vicinity, though some questions about storm mode, the low-level thermodynamics, and about how backed the low-level flow will be probably puts a lid on how many tornadoes stronger than EF-2/3 we can see out of this setup, which probably argues against them pulling that trigger. 10% hatched into the Deep South seems warranted given obvious strong tornado potential given the low-level shear and expected storm mode but questions about the low-level thermodynamics. 

[MidwestChaser]

No real changes on the latest Day 1.

[ILSNOW]

From storm prediction center 

 The northern portion of this convection will be oriented more orthogonal to the ejecting
 mid-level jet, and current expectations are for quick upscale growth
 into a fast northeastward-moving band, posing a risk for widespread
 severe/damaging winds as this activity moves into IA and towards the
 MO/IA/IL border region. Given the strength of the low/mid-level flow
 and presence of steep lapse rates aloft, along with a well-mixed
boundary layer, intense thunderstorm straight-line gusts peaking
locally in the 80-100 mph range are possible with the stronger
cores/inflections in the band as it matures and moves across parts
 of the mid MS Valley, and eventually into the southwestern Great
 Lakes this evening through tonight. 

[Powerball]

The current initial convection moving through MO which at first did seem like it would rev up (but is outrunning the better dynamics / moisture advection) has somewhat throw a wrench into things (as mentioned, it's not being handled very well by CAMs), especially as it cuts into daytime heating.

That's probably another reason why they held off on the high risk.

[Lurkess]

1 hour ago, nvck said:

HREF with a UH bullseye around and north of STL tonight.

Holy moly!  That's us, surrounded.  Reminds me of 2012 outbreak.  Thanks for posting!

[Lurkess]

33 minutes ago, ILSNOW said:

From storm prediction center 

 The northern portion of this convection will be oriented more orthogonal to the ejecting
 mid-level jet, and current expectations are for quick upscale growth
 into a fast northeastward-moving band, posing a risk for widespread
 severe/damaging winds as this activity moves into IA and towards the
 MO/IA/IL border region. Given the strength of the low/mid-level flow
 and presence of steep lapse rates aloft, along with a well-mixed
boundary layer, intense thunderstorm straight-line gusts peaking
locally in the 80-100 mph range are possible with the stronger
cores/inflections in the band as it matures and moves across parts
 of the mid MS Valley, and eventually into the southwestern Great
 Lakes this evening through tonight. 

OMG!  We don't have the infrastructure here for this.  Last windstorm a few years ago buried the village, crushed houses with 100+ year old hardwood trees.  Thanks for posting.  

[HillsdaleMIWeather]

Day 2 high risk coming in 10 mins

[Lurkess]

59 minutes ago, OHweather said:

There will probably be a shit load of tornadoes from central and eastern MO into western and central IL, with the threat for stronger tornadoes probably maximized in the vicinity of St Louis later this evening. There will also be a ton of straight-line wind damage. A secondary threat for potentially stronger tornadoes is evident from MS into northern/western AL as well later this afternoon/evening.

Pretty impressive model agreement on either a line, or a mixed arc of bowing segments and some embedded semi-discrete supercells evolving from MO into IA and IL this afternoon and evening, with some tendency for more cells towards the southern end of that. Some models keep this activity semi-discrete (or at least maintain decent line breaks) through much of the evening, especially into central/southern IL. This activity will be extremely strongly forced. Most CAMS other than the 3km NAM have a cluster of more weakly-forced convection developing from eastern AR/LA into MS and western/northern AL. Evolutions vary a bit more with that activity, likely due to weaker forcing. There likely will be a relative minimum in severe/tornado potential centered on western TN between these two areas, though some models have more isolated activity trying to play out even there. 

3km NAM:

HRRR:

ARW:

NSSL:

 

They look slightly different but all agree on the overall evolution in both regimes fairly well (sans the NAM in Dixie today). No model is handling the current elevated convection great, though after 20z I kind of like the HRRR's and NSSL's reflectivity and overall evolution just a bit more than some others. 

You can get the idea that the northern activity in MO/IA/IL is much more strongly forced than the Dixie activity today:

Something to keep in mind, the 500-700mb jet doesn't really punch into the warm sector in the upper Mississippi Valley until after 0z...so, shear profiles will already be impressive this afternoon and will improve markedly after 0z...500mb:

700mb (which is roughly 3km, so think of your 0-3km bulk shear vector for bowing segments and mesovort tornado potential, along with your 0-3km SRH). Low-level shear will be strong in the warm sector this afternoon and explode starting right around 0z this evening:

Activity in the Deep South will be driven largely by a rich low-level jet, though even some of that lifts into the upper Mississippi Valley after 0z:

The strong forcing argues for quick upscale growth in MO, IA, and IL this afternoon and evening, and most of the CAMs above do have a more linear mode than cellular. However, most do have hints of a more semi-discrete mode from east-central MO across central/southern IL and perhaps into far west-central IN. It is in this area where for several hours after 0z the bulk shear vectors are oriented 30-45 degrees across the expected convective line, which does argue for right-moving cells. The forcing is also a bit weaker farther south, which could assist in maintaining a somewhat more discrete mode:

Some maybe representative soundings...from North Central MO late this afternoon:

The shear is quite strong and the thermodynamics are sufficient for severe weather and not prohibitive for tornadoes...however, the thermodynamics could be better and the low-level flow is fairly unidirectional. 

East-central MO later this evening:

While the low-levels aren't extremely unstable they're unstable enough, with 1500 J/KG of MLCAPE being fully sufficient for significant severe weather and tornadoes. The low-level flow could still be more backed (and may locally back more than this), though even without it the increased low-level shear after 0z increases effective SRH notably. Any bowing segments in this environment would be capable of swaths of sig wind damage and tornadoes as well...however, the main concern is if semi-discrete cells interact with this environment as some signs point to. Strong tornado potential is evident, though there are subtle limitations which may keep the ceiling for this event from blowing into the stratosphere. 

Here's a look at a sounding in central Mississippi this evening:

Upon clicking around several of these soundings to find representative ones, I found the low-level shear to be best in the Deep South. However, the low-level lapse rates are quite weak with richly moist low-levels. That could be a limiting factor for greater tornado potential...however, the fact that most CAMs have discrete or semi-discrete cells playing out in this environment suggests tornado (potentially strong) potential, even if there are limitations. 

Overall, I would suggest patience. Storms will probably be severe with scattered to numerous straight-line wind reports, scattered hail, and a few tornadoes this afternoon in MO/southern IA...the northern threat likely maximizes starting around 0z, with potential for somewhat more discrete activity on the southern edge of that from east-central MO into central/southern IL. The environment this evening will support widespread/significant wind damage with any bows, along with QLCS tornadoes, with any supercells capable of all hazards including strong tornadoes. The tornado threat will gradually decrease with northern/eastern extent into IA, northern IL, southwest MI and across IN, though given the strong low-level shear QLCS tornadoes can't be ruled out where any surface-based CAPE persists overnight, assuming some organized convection can persist. There may be a relative min in severe coverage in the vicinity of western TN, with a secondary threat area focused on MS and western/northern AL. This southern threat area has tornado (potentially strong) potential, but with some overall limitations. 

I think east-central MO into central/southern IL has the greatest severe wx and intense tornado potential overall today and tonight, though there is a much broader area with severe/some tornado potential across MO/IA/IL/southern WI/southwest MI/IN. I could see the coverage of tornadoes and EF-2+ verifying a small 30% hatched area in practically perfect verification in the MO/IL vicinity, though some questions about storm mode, the low-level thermodynamics, and about how backed the low-level flow will be probably puts a lid on how many tornadoes stronger than EF-2/3 we can see out of this setup, which probably argues against them pulling that trigger. 10% hatched into the Deep South seems warranted given obvious strong tornado potential given the low-level shear and expected storm mode but questions about the low-level thermodynamics. 

Oh boy are we screwed. Can't evacuate, no shelter, spine causing oxygen issues.  Could pack up car and leave but surrounded.  Thanks for posting!

[SchaumburgStormer]

Day 2 high risk down south. Nice. 

[Powerball]

R.I.P Birmingham...

[nvck]

Wow

[Powerball]

[Powerball]

Kind of interesting, BTW, to see what appears to be some cloud seeding with the dust on Satellite..

[mob1]

New line of convection going on in eastern KS, environment ahead of it seems to be recovering decently from the morning precipitation.  

[Powerball]

https://x.com/NWSSPC/status/1900627755374379121?t=CRhJ-hEb9K_uNTUgRgzklQ&s=19

 

[fluoronium]

I think I'll head down to just east of STL and let the storms chase me up i70. It should be a fun time. The next couple days have a good shot at setting records for number of severe reports.

[hawkeye_wx]

The Weather Channel has a Torcon of 9 out of 10 for Jackson, MS tomorrow.

[Powerball]

1 minute ago, Powerball said:

https://x.com/NWSSPC/status/1900627755374379121?t=CRhJ-hEb9K_uNTUgRgzklQ&s=19