Severe Weather for Oklahoma and Kansas 5/6/24 (High Risk latched by SPC)

[snownado]

 https://twitter.com/NWSSevereTstorm/status/1787578058104562121

[storm_in_a_teacup]

I wanted to go over some of the synoptics for today's severe weather potential. I'll focus mainly on the SPC hatched area, but the potential for severe weather and tornadoes extends along the entire eastern flank of the negatively tilted trough.

If we're looking for severe weather potential, this is a classic setup with the negatively tilted trough extending down towards Texas/GOM:
https://i.imgur.com/FDyKtOD.jpeg

This is a full animation of the trough's progression throughout the day, and you can see as we get later on (around 00 UTC), the level of ascent (blue shaded areas) really amplifies:
https://i.imgur.com/3aUUTBB.gif
https://www.atmos.albany.edu/student/abentley/realtime/standard.php?domain=northamer&variable=rel_vort

One of the reasons for this is significant low-level theta advection from the GOM/Mexico region. When we have this type of advection with a negatively tilted trough, it really amplifies potential vorticity and CAPE:
https://i.imgur.com/lqSuesq.png
https://www.atmos.albany.edu/student/abentley/realtime/standard.php?domain=northamer&variable=850_thetae

CAPE values
https://i.imgur.com/vPAO7u5.png
https://www.pivotalweather.com/model.php?p=mucape&rh=2024050606&fh=18

In addition, we have a moderate-high shear environment
https://i.imgur.com/NC4Sn0O.png
https://www.pivotalweather.com/model.php?p=bs0500&rh=2024050606&fh=18

When you combine all of these factors (high CAPE values/ascent, high shear from sfc-500mb, and a negatively tilted trough), this creates the potential for severe and significant supercells. If we were to look at an animation of soundings with hodographs for the hatched area, we can see how the wind speed translates from aloft towards the surface as the day progresses. Winds also shift clockwise (known as veering, or clockwise turning of the wind barbs with height—veering winds are associated with warm air advection and produce significant thunderstorms):
https://i.imgur.com/QxjTlIp.gif

What does a negatively tilted trough mean? Like negative in which manner?

[snownado]

I wanted to go over some of the synoptics for today's severe weather potential. I'll focus mainly on the SPC hatched area, but the potential for severe weather and tornadoes extends along the entire eastern flank of the negatively tilted trough.

If we're looking for severe weather potential, this is a classic setup with the negatively tilted trough extending down towards Texas/GOM:
https://i.imgur.com/FDyKtOD.jpeg

This is a full animation of the trough's progression throughout the day, and you can see as we get later on (around 00 UTC), the level of ascent (blue shaded areas) really amplifies:
https://i.imgur.com/3aUUTBB.gif
https://www.atmos.albany.edu/student/abentley/realtime/standard.php?domain=northamer&variable=rel_vort

One of the reasons for this is significant low-level theta advection from the GOM/Mexico region. When we have this type of advection with a negatively tilted trough, it really amplifies potential vorticity and CAPE:
https://i.imgur.com/lqSuesq.png
https://www.atmos.albany.edu/student/abentley/realtime/standard.php?domain=northamer&variable=850_thetae

CAPE values
https://i.imgur.com/vPAO7u5.png
https://www.pivotalweather.com/model.php?p=mucape&rh=2024050606&fh=18

In addition, we have a moderate-high shear environment
https://i.imgur.com/NC4Sn0O.png
https://www.pivotalweather.com/model.php?p=bs0500&rh=2024050606&fh=18

When you combine all of these factors (high CAPE values/ascent, high shear from sfc-500mb, and a negatively tilted trough), this creates the potential for severe and significant supercells. If we were to look at an animation of soundings with hodographs for the hatched area, we can see how the wind speed translates from aloft towards the surface as the day progresses. Winds also shift clockwise (known as veering, or clockwise turning of the wind barbs with height—veering winds are associated with warm air advection and produce significant thunderstorms):
https://i.imgur.com/QxjTlIp.gif

What does a negatively tilted trough mean? Like negative in which manner?

https://www.theweatherprediction.com/habyhints/127/

[USTropics]

I wanted to go over some of the synoptics for today's severe weather potential. I'll focus mainly on the SPC hatched area, but the potential for severe weather and tornadoes extends along the entire eastern flank of the negatively tilted trough.

If we're looking for severe weather potential, this is a classic setup with the negatively tilted trough extending down towards Texas/GOM:
https://i.imgur.com/FDyKtOD.jpeg

This is a full animation of the trough's progression throughout the day, and you can see as we get later on (around 00 UTC), the level of ascent (blue shaded areas) really amplifies:
https://i.imgur.com/3aUUTBB.gif
https://www.atmos.albany.edu/student/abentley/realtime/standard.php?domain=northamer&variable=rel_vort

One of the reasons for this is significant low-level theta advection from the GOM/Mexico region. When we have this type of advection with a negatively tilted trough, it really amplifies potential vorticity and CAPE:
https://i.imgur.com/lqSuesq.png
https://www.atmos.albany.edu/student/abentley/realtime/standard.php?domain=northamer&variable=850_thetae

CAPE values
https://i.imgur.com/vPAO7u5.png
https://www.pivotalweather.com/model.php?p=mucape&rh=2024050606&fh=18

In addition, we have a moderate-high shear environment
https://i.imgur.com/NC4Sn0O.png
https://www.pivotalweather.com/model.php?p=bs0500&rh=2024050606&fh=18

When you combine all of these factors (high CAPE values/ascent, high shear from sfc-500mb, and a negatively tilted trough), this creates the potential for severe and significant supercells. If we were to look at an animation of soundings with hodographs for the hatched area, we can see how the wind speed translates from aloft towards the surface as the day progresses. Winds also shift clockwise (known as veering, or clockwise turning of the wind barbs with height—veering winds are associated with warm air advection and produce significant thunderstorms):
https://i.imgur.com/QxjTlIp.gif

What does a negatively tilted trough mean? Like negative in which manner?

It's the orientation of the trough axis, and this particular shortwave trough has actually undergone all 3 phases. You can determine the orientation by using the 500mb height contours here.

If it's oriented NE to SW, we call this positively tilted. There typically isn't severe weather associated with this type of orientation:


When it's oriented N to S, we call it neutral. This can sometimes produce severe weather:


when it's tilted from NW to SE we call this negatively tilted. It's often associated with severe weather:


There are a few reasons our trough has negatively tilted. For starters, we can see we have a jet streak positioned to the south/base of our trough axis:


Why is this important? I won't get too much into the weeds on jet streaks, but this is a conceptual model of a jet streak I did for a class, and you can see in the left exit region we have divergence aloft (air is spreading out). if you overlay this with the map above, and we have divergence aloft, this further increases convergence at the surface (air is colliding from two different directions, forcing ascent):


Another reason is this expansive ridge to the east of our trough axis. This acts to 'slow down' the trough so to speak, allowing it to become tilted:


We can further analyze both the upper levels and lower levels. Here we have our dynamic tropopause (upper levels), where when we have this gradient (blue shading converges with our pinks/reds), we have colder air being advected, and we expect +PV (further lifting):


We can do the same thing at the surface. In this instance, where we have warmer air being advected, we have +PV again:

[storm_in_a_teacup]

I wanted to go over some of the synoptics for today's severe weather potential. I'll focus mainly on the SPC hatched area, but the potential for severe weather and tornadoes extends along the entire eastern flank of the negatively tilted trough.

If we're looking for severe weather potential, this is a classic setup with the negatively tilted trough extending down towards Texas/GOM:
https://i.imgur.com/FDyKtOD.jpeg

This is a full animation of the trough's progression throughout the day, and you can see as we get later on (around 00 UTC), the level of ascent (blue shaded areas) really amplifies:
https://i.imgur.com/3aUUTBB.gif
https://www.atmos.albany.edu/student/abentley/realtime/standard.php?domain=northamer&variable=rel_vort

One of the reasons for this is significant low-level theta advection from the GOM/Mexico region. When we have this type of advection with a negatively tilted trough, it really amplifies potential vorticity and CAPE:
https://i.imgur.com/lqSuesq.png
https://www.atmos.albany.edu/student/abentley/realtime/standard.php?domain=northamer&variable=850_thetae

CAPE values
https://i.imgur.com/vPAO7u5.png
https://www.pivotalweather.com/model.php?p=mucape&rh=2024050606&fh=18

In addition, we have a moderate-high shear environment
https://i.imgur.com/NC4Sn0O.png
https://www.pivotalweather.com/model.php?p=bs0500&rh=2024050606&fh=18

When you combine all of these factors (high CAPE values/ascent, high shear from sfc-500mb, and a negatively tilted trough), this creates the potential for severe and significant supercells. If we were to look at an animation of soundings with hodographs for the hatched area, we can see how the wind speed translates from aloft towards the surface as the day progresses. Winds also shift clockwise (known as veering, or clockwise turning of the wind barbs with height—veering winds are associated with warm air advection and produce significant thunderstorms):
https://i.imgur.com/QxjTlIp.gif

What does a negatively tilted trough mean? Like negative in which manner?

It's the orientation of the trough axis, and this particular shortwave trough has actually undergone all 3 phases. You can determine the orientation by using the 500mb height contours here.

If it's oriented NE to SW, we call this positively tilted. There typically isn't severe weather associated with this type of orientation:
https://i.imgur.com/cBbfFwa.jpeg

When it's oriented N to S, we call it neutral. This can sometimes produce severe weather:
https://i.imgur.com/2Hh0S1P.jpeg

when it's tilted from NW to SE we call this negatively tilted. It's often associated with severe weather:
https://i.imgur.com/dMwg7JC.jpeg

There are a few reasons our trough has negatively tilted. For starters, we can see we have a jet streak positioned to the south/base of our trough axis:
https://i.imgur.com/XZeW8z3.jpeg

Why is this important? I won't get too much into the weeds on jet streaks, but this is a conceptual model of a jet streak I did for a class, and you can see in the left exit region we have divergence aloft (air is spreading out). if you overlay this with the map above, and we have divergence aloft, this further increases convergence at the surface (air is colliding from two different directions, forcing ascent):
https://i.imgur.com/lPOtMX6.jpeg

Another reason is this expansive ridge to the east of our trough axis. This acts to 'slow down' the trough so to speak, allowing it to become tilted:
https://i.imgur.com/M3LB2uk.jpeg

We can further analyze both the upper levels and lower levels. Here we have our dynamic tropopause (upper levels), where when we have this gradient (blue shading converges with our pinks/reds), we have colder air being advected, and we expect +PV (further lifting):
https://i.imgur.com/Z9L6jLG.png

We can do the same thing at the surface. In this instance, where we have warmer air being advected, we have +PV again:
https://i.imgur.com/vNhyXLP.png

Thanks for this. I'm a scientist, but one who studies black holes lol, not weather, so a lot of this is new to me.

[USTropics]

Strong hook signature that just passed over Barnsdall, OK:


 https://twitter.com/landon_wx/status/1787681373072871676

[ElectricStorm]

It only takes one....

Thats by far the strongest tornado I've seen in that area. I hope they were prepared.

[ElectricStorm]

I personally don't like using the word "bust" because that makes it sound like nothing happened. But there's no doubt about this that was one of the biggest underperforming high risks maybe ever. So far verifying as just a 5%, although this may go up a bit depending on if they find any QLCS spin ups although it probably won't be much.
 https://twitter.com/Brady_Wx/status/1787869886963749199




Obviously hindcast is 20/20 but I've seen some good discussions on Twitter and I'm starting to think the environment just wasn't that good for tornadoes as originally thought. Not sure the exact culprit but I've seen a few things thrown around, like a VBV wind profile, poor lapse rates, dry air aloft, and obviously storm mode which was a major culprit overall. That would be something interesting to look into though.

Of course this is yet another example of "it only takes one" with the intense tornado in Barnsdall and Bartlesville, which was the only cell the entire day to really get going from a tornado perspective (wondering if that had to do with the approaching line similar to 4/27 southern Oklahoma event) and that area wasn't even in the high risk until the 1z update.

Definitely will be a good case study for forecasting in the future, since it seemed like a pretty clear cut high risk environment (and I certainly would have upgraded if it were me) that somehow failed to materialize.

Also interesting to note that all 3 high risks in Oklahoma since the introduction of the 5 tier scale (5/18/17, 5/20/19, and now this one) have all been major underperformances.

[ElectricStorm]

Also a really good thread here from Cameron Nixon

 https://twitter.com/CameronJNixon/status/1787909257549201879

[snownado]

Also a really good thread here from Cameron Nixon

https://twitter.com/CameronJNixon/status/1787909257549201879?t=VCPBYcTZH6KDWV_nbEYu9g&s=19

So the TL;DR hypothesis, from what I gather, was insufficient surface heating (not surprising with all of the low stratus) and moist-adiabetic lapse rates aloft...

[Brent]

Barnsdall is ef4 now

[USTropics]

Large wedge tornado down just ENE of Columbia, TN. Clear hook signature on radar:



 https://twitter.com/RadarOmega/status/1788340840672186418

[Iceresistance]

Forgot to update, but I am alright