December 12-14, 2022 | Significant Tornado Outbreak

[Iceresistance]

Weird, the SPC dropped the Slight Risk for Monday, 12/12. That means nothing to me, I'm still watching it for surprises. 

[Ingyball]

I'm a little bit confused on what SPC is doing. Usually if a system is trending slower you don't completely drop an outlook you shift or expand the previous one west. I think there's enough support to have continued the 15%, especially down in Texas. Some interesting soundings up in southern Nebraska too.

Southwest Nebraska

Maybe some cold air funnels up there? Wouldn't take too much of a southwest shift to turn this into a legit severe threat.

Northwest/southwest Texas

This is where I would have shifted the 15%. The severe threat may not be as high end, but it's still there. Dropping the D4 is telling the public that the severe threat is gone and shifted east. Had they kept the previous one, shifted and expanded west some and kept it over DFW not only is it still highlighting the severe threat, but it also helps with continued slow trends that may shift the threat further west on Tuesday. It keeps people in DFW aware of the potential.

 

There is definitely some potential Monday night imo though. There's a split flow jet streak at 200mb over southwest Texas and at 300mb the jet streak displaced further north. With the potential for ELs to get up to 200mb this would allow for some impressive shear, but due to the fast moving air above slow moving air we should see some rising motion as air needs to be replaced.

[ClicheVortex2014]

One piece of this setup is pushing on shore. It’s not the main system, but it’s going to move zonally across the country. Though it’s a weak system, it helps pool moisture in the Gulf coast. This system will be sampled by this evenings launch, so hopefully that’ll help the models settle on moisture for Tuesday.
 

Partial sampling of the main system will begin tomorrow 12z. Near full sampling by Sunday evening. 

[Chinook]

13 hours ago, Ingyball said:

I'm a little bit confused on what SPC is doing. Usually if a system is trending slower you don't completely drop an outlook you shift or expand the previous one west. I think there's enough support to have continued the 15%, especially down in Texas. Some interesting soundings up in southern Nebraska too.

Southwest Nebraska

Maybe some cold air funnels up there? Wouldn't take too much of a southwest shift to turn this into a legit severe threat.

Northwest/southwest Texas

This is where I would have shifted the 15%. The severe threat may not be as high end, but it's still there. Dropping the D4 is telling the public that the severe threat is gone and shifted east. Had they kept the previous one, shifted and expanded west some and kept it over DFW not only is it still highlighting the severe threat, but it also helps with continued slow trends that may shift the threat further west on Tuesday. It keeps people in DFW aware of the potential.

 

There is definitely some potential Monday night imo though. There's a split flow jet streak at 200mb over southwest Texas and at 300mb the jet streak displaced further north. With the potential for ELs to get up to 200mb this would allow for some impressive shear, but due to the fast moving air above slow moving air we should see some rising motion as air needs to be replaced.

there is CAPE is Nebraska? weird

[Ingyball]

27 minutes ago, Chinook said:

there is CAPE is Nebraska? weird

Yup, likely due to the very high lapse rates. 

[Ingyball]

NAM doing NAM things in western Kansas Monday evening. Low topped Supercells perhaps? Lol 

[Neoncyclone]

2 hours ago, Ingyball said:

NAM doing NAM things in western Kansas Monday evening. Low topped Supercells perhaps? Lol 

What an interesting sounding honestly, 8.3C LLLR's

Edited December 10, 2022 by Neoncyclone

[ClicheVortex2014]

I've been doing evening balloon launches this week (being shadowed still), except for yesterday because I was sick, but today was a pretty solid one. Some serious moisture advection going on.

Edited December 10, 2022 by ClicheVortex2014

[Ingyball]

There may be some potential in western Kansas Monday night. Hope SPC doesn't sleep on it. 

 

[Ingyball]

Nice signal for rain on EFI. We need it. 

[ClicheVortex2014]

Long thread with pictures of 12/10

 

[Ingyball]

You can always count on the FV3 to find a way to make Supercells lol. 

 

That said if this were April or May we're probably talking about the worst Plains outbreak in the last decade right now. 

[ClicheVortex2014]

Sounding for midnight in the NE TX panhandle. That's some serious lapse rates.

Edited December 11, 2022 by ClicheVortex2014

[Iceresistance]

30 minutes ago, ClicheVortex2014 said:

Sounding for midnight in the NE TX panhandle. That's some serious lapse rates.

May not take much for the Supercells to explode, the SPC is in for a nasty surprise for Monday. 

[ClicheVortex2014]

Just now, Iceresistance said:

May not take much for the Supercells to explode, the SPC is in for a nasty surprise for Monday. 

If that pans out, yeah, severe weather could start very early in the morning. But I'm not sure I buy something as crazy as NAM yet. There has been plenty of signs about the initial activity to rule anything out though

[ClicheVortex2014]

*SO FAR* I'm not as impressed with this event as I was with the last. 

My one bold prediction at this point is that NAM is under-doing moisture in the warm sector. GFS has stronger moisture than it, so that's a huge red flag to me when NAM is this far out. GFS should have a better handle on the system at large which affects the qualities of the warm sector.

Below 3 gifs are comparisons of GFS and NAM. Notice NAM is quicker than GFS

 

Northern LA on GFS. Moderate instability, strong deep-layer shear, strong low-level shear, but the 2-5km layer has almost no speed shear. So shear isn't continuous through the profile, but I don't think that matters much.

Edited December 11, 2022 by ClicheVortex2014

[Ingyball]

3 minutes ago, ClicheVortex2014 said:

*SO FAR* I'm not as impressed with this event as I was with the last. 

My one bold prediction at this point is that NAM is under-doing moisture in the warm sector. GFS has stronger moisture than it, so that's a huge red flag to me when NAM is this far out. GFS should have a better handle on the system at large which affects the qualities of the warm sector.

Below 3 gifs are comparisons of GFS and NAM

 

Northern LA on GFS. Moderate instability, strong deep-layer shear, strong low-level shear, but the 2-5km layer has almost no speed shear. So shear isn't continuous through the profile, but I don't think that matters much.

The position of the Jet isn't quite as good this go around. Would like to see it closer to the warm sector. I think the better dynamics will be Monday night and Tuesday morning further west, but time of year and time of day should help put a lid on anything crazy.

[ClicheVortex2014]

25 minutes ago, Ingyball said:

The position of the Jet isn't quite as good this go around. Would like to see it closer to the warm sector. I think the better dynamics will be Monday night and Tuesday morning further west, but time of year and time of day should help put a lid on anything crazy.

The low being so far away could lead to the frontal squall tapering off toward the warm sector, maybe leading to semi-discrete action. GFS and NAM are hinting at this.

That said, the warm sector of a very occluded system like this might have height rise which can kill potential for warm sector convection. 

Good thing SPC doesn't have to issue tornado probabilities with the day 3. Enhanced risk for damaging wind is pretty safe.

Edited December 11, 2022 by ClicheVortex2014

[Neoncyclone]

Something to note as we get closer to the event

 

[Iceresistance]

The reason why Monday is Marginal for the Plains

Uncertainty remains regarding the potential for near-surface-based
   development during the evening/overnight hours. Cool surface
   temperatures and late initiation will generally not be supportive of
   sustained surface-based storms. Low-level moisture return may become
   sufficient across parts of western north TX into southwest OK for
   storms to become rooted near the surface. Meanwhile, across parts of
   western KS, cold midlevel temperatures (500 mb temperatures at or
   below -20C) could support some increase in MLCAPE and decrease in
   MLCINH, despite temperatures generally remaining in the low 50s F.
   In these areas, relatively strong low-level shear/SRH may support a
   brief tornado threat with any sustained supercell or QLCS
   development. 

 

[ClicheVortex2014]

11 hours ago, Neoncyclone said:

Something to note as we get closer to the event

 

I was surprised to see the 12z NAM bring the warm sector into east Texas on Tuesday. Starting to get sampling of the actual system so this may not be a fluke.
 

I haven’t checked 12z GFS yet and won’t do anything weather related until after the bengals game

Edited December 11, 2022 by ClicheVortex2014

[Chinook]

for those interested, the Pivotalweather special forecast fields from the ECMWF is open to the general public right now

 

[Iceresistance]

1 hour ago, Chinook said:

for those interested, the Pivotalweather special forecast fields from the ECMWF is open to the general public right now

 

It actually for ALL models because of login issues!

[ClicheVortex2014]

HRRR is meh. No doubt there are some supercells but not the kind that have the potential to be long-lived.

[CentralLA_Wx]

Sigtor values not looking quite as high as the Nov 29 event (at least when compared to two days before event unfolding). 45 near my area around midnight Tues night. Larger 45 sigtor zone for SE LA and S MS Wednesday afternoon. 

 

 

Edited December 12, 2022 by CentralLA_Wx