Severe WX April 11-14th, 2022 Severe Weather Threat

[TH2002]

I know everyone's eyes are on the MASSIVE 30% risk area in the D4 outlook, but the GFS SCP does show some potential in SE OK for tomorrow

 

[DetectiveWX]

I know everyone's eyes are on the MASSIVE 30% risk area in the D4 outlook, but the GFS SCP does show some potential in SE OK for tomorrow
View attachment 13353

Speaking of which, here's Jeff from twitter with an interesting analog for Tues in the Plains.

 

[tennessee storm chaser]

I know everyone's eyes are on the MASSIVE 30% risk area in the D4 outlook, but the GFS SCP does show some potential in SE OK for tomorrow
View attachment 13353

good point, its got start somewhere...

 

[CheeselandSkies]

Speaking of which, here's Jeff from twitter with an interesting analog for Tues in the Plains.

Counterpoint, from Brett Roberts on Stormtrack:

2022-04-10 to -14 EVENT: KS/OK/MO

If the 12Z ECMWF is correct, there will be the most impressive Central Plains multi-day event in years. From a pattern recognition perspective, it reminds me of May 3-8, 2003. The model's surface forecast is especially similar to May 8, 2003, but 2022 is, perhaps, 50 miles farther south based...

stormtrack.org

Just about 36-48 hours ago I did agree Tuesday had 4/26/91 level potential, but that was before the NAM came in showing massive capping issues and @Fred Gossage pointed out some of the other problems.

That said, the RAP now comes in worlds apart from the NAM showing the warm front advancing much deeper into Iowa Tuesday afternoon/evening, with a breakable cap before dark (I am focusing on the northern reaches of the setup for both Tuesday and Wednesday, since that is where my chase range is limited to with only being able to take one day off on short notice).

 

[Fred Gossage]

Wednesday is one of those odd scenarios for the lower Mississippi Valley/mid-South where it seems like the main surface low/triple point is too far away for a significant event in the region.

If there are surface pressure falls with time or height falls aloft, that matters zero. The F5 in central Mississippi on March 3, 1966 happened why the surface low was in central South Dakota. The surface low for November 10, 2002 moved into southern Canada that morning. The two EF4 tornadoes in southern Alabama on March 1, 2007 happened with the surface low track into Minnesota and Wisconsin. There are countless examples. If there are height falls aloft, divergence/diffluence aloft, and surface pressure falls... all so that the low-level flow isn't veered too much and you have large scale ascent in place... the storms don't know where a surface low is on a map. All they feel is the environment available to them. There are countless examples. Otherwise, we'd be able to erase a LOT of the strong/violent tornadoes in history from the Southeast. Surface low placement becomes a problem when it also occludes early enough before the threat to a particular area that low-level winds start veering with time, and it seems like it's the culprit when it coincides with the mid/upper dynamics also pulling away.

 

[CheeselandSkies]

If there are surface pressure falls with time or height falls aloft, that matters zero. The F5 in central Mississippi on March 3, 1966 happened why the surface low was in central South Dakota. The surface low for November 10, 2002 moved into southern Canada that morning. The two EF4 tornadoes in southern Alabama on March 1, 2007 happened with the surface low track into Minnesota and Wisconsin. There are countless examples. If there are height falls aloft, divergence/diffluence aloft, and surface pressure falls... all so that the low-level flow isn't veered too much and you have large scale ascent in place... the storms don't know where a surface low is on a map. All they feel is the environment available to them. There are countless examples. Otherwise, we'd be able to erase a LOT of the strong/violent tornadoes in history from the Southeast. Surface low placement becomes a problem when it also occludes early enough before the threat to a particular area that low-level winds start veering with time, and it seems like it's the culprit when it coincides with the mid/upper dynamics also pulling away.

That's why said "seems"...

 

[Brice Wood]

Speaking of which, here's Jeff from twitter with an interesting analog for Tues in the Plains.

4 F4s, the infamous Andover F5…. Yikes

 

[tennessee storm chaser]

Latest hrrr now is showing discrete super cellular activity tomorrow evening over west Arkansas . Wouldn’t be suprise see upgrade enhance morning

 

[Taylor Campbell]

I think an enhanced risk is a good call for Tuesday. I don't see a reason to go moderate or high risk at this stage. Though, a moderate risk could be sufficient with time for hail.

 

[MattPetrulli]

For tomorrow, think 5% is a good call where at face value an enhanced tornado threat seems present given shear and convective evolution but I think storms will have a hard time getting rooted at the surface and may remain elevated.

This sounding demonstrates it pretty well, with a capping inversion at the surface.
For thoughts on Tuesday and Wednesday, am not really convinced of much happening on Tuesday outside of the TP at this point. Think there could be a sig tor threat around triple point in LIEowa around dark or just after given 00z but even that's low confidence atm.
Wednesday has been pretty mediocre on 12z and 18z Euro and 18z GFS is a little better in terms of tor potential, but not close to the NAM. 00z NAM as it has been showing all day is still a widespread significant event and the end of the 3km NAM looks to support that, however end of FV3 is likely closer to the GFS side. I would like to see a model other than NAM show a big time event to gain confidence in that. That being said, NAM absolutely nailed the event last week while globals were pretty bearish, so that's something to keep in mind.

 

[tennessee storm chaser]

For tomorrow, think 5% is a good call where at face value an enhanced tornado threat seems present given shear and convective evolution but I think storms will have a hard time getting rooted at the surface and may remain elevated.
View attachment 13354
This sounding demonstrates it pretty well, with a capping inversion at the surface.
For thoughts on Tuesday and Wednesday, am not really convinced of much happening on Tuesday outside of the TP at this point. Think there could be a sig tor threat around triple point in LIEowa around dark or just after given 00z but even that's low confidence atm.
Wednesday has been pretty mediocre on 12z and 18z Euro and 18z GFS is a little better in terms of tor potential, but not close to the NAM. 00z NAM as it has been showing all day is still a widespread significant event and the end of the 3km NAM looks to support that, however end of FV3 is likely closer to the GFS side. I would like to see a model other than NAM show a big time event to gain confidence in that. That being said, NAM absolutely nailed the event last week while globals were pretty bearish, so that's something to keep in mind.

Think Wednesday has a high ceiling potential, the ukie and euro been pretty much lock n step showing an significant event . Cmc also u can add now nam starting get in range showing significant severe outbreak … going on limb this far out , but if Wednesday goes high , se Arkansas / nw ms/ sw tenn should be it.

 

[MattPetrulli]

Think Wednesday has a high ceiling potential, the ukie and euro been pretty much lock n step showing an significant event . Cmc also u can add now nam starting get in range showing significant severe outbreak … going on limb this far out , but if Wednesday goes high , se Arkansas / nw ms/ sw tenn should be it.

Forgot to look at UK met, yeah UKmet is with NAM suite, also Euro isn't as bad on second look, has some good soundings in pocketed areas, but it's also a global model so more interested in mesoscale models at this stage.
Edit: Also 18z GFS is good for areas about south of OH river, has a potentially significant event there, but doesn't have northern extent like NAM.

 

[andyhb]

00z UK... holy moly for Wednesday.

 

[tennessee storm chaser]

Wow what a new day 3 outlook now… east extent of it now goes to I 65 …. Also 30 percent hatched

 

[Fred Gossage]

For tomorrow, think 5% is a good call where at face value an enhanced tornado threat seems present given shear and convective evolution but I think storms will have a hard time getting rooted at the surface and may remain elevated.
View attachment 13354
This sounding demonstrates it pretty well, with a capping inversion at the surface.
For thoughts on Tuesday and Wednesday, am not really convinced of much happening on Tuesday outside of the TP at this point. Think there could be a sig tor threat around triple point in LIEowa around dark or just after given 00z but even that's low confidence atm.
Wednesday has been pretty mediocre on 12z and 18z Euro and 18z GFS is a little better in terms of tor potential, but not close to the NAM. 00z NAM as it has been showing all day is still a widespread significant event and the end of the 3km NAM looks to support that, however end of FV3 is likely closer to the GFS side. I would like to see a model other than NAM show a big time event to gain confidence in that. That being said, NAM absolutely nailed the event last week while globals were pretty bearish, so that's something to keep in mind.

What that forecast sounding shows is nocturnal boundary layer decoupling. However, when you have dewpoints well into the 60s like that and low-level winds that strong, it would defy this planet's physics for that near-surface inversion to actually develop. This is one of the same PBL biases in almost all modeling that is seen most prevalent in the cool season that causes after-dark instability to be underdone by modeling, but it definitely does happen in the spring as well. That decoupling happens from radiational cooling at the surface after dark, but think of just a non-severe weather day and what you need for radiational cooling to be more effective after dark: clear skies, dry air, calm winds. In that environment there, you have none of those things. The boundary layer would not actually decouple, surface temperatures would probably be in the 72-74F range unless cooled by rain-cooled air from convection moving overhead or unless a boundary moves through, and instability would remain surface-based without the convective inhibition modeled actually being there.

 

[CheeselandSkies]

00z UK... holy moly for Wednesday.

It's kind of an outlier holding the front back across the MS River with a secondary SLP over IL though, isn't it? As awesome as it would be from a chase perspective to have that solution verify, I don't think it's likely.

 

[Timhsv]

00z UK... holy moly for Wednesday.

Are you talking Andy in respect to the tilt of the trough or what particularly?

 

[tennessee storm chaser]

It's kind of an outlier holding the front back across the MS River with a secondary SLP over IL though, isn't it? As awesome as it would be from a chase perspective to have that solution verify, I don't think it's likely.

It's kind of an outlier holding the front back across the MS River with a secondary SLP over IL though, isn't it? As awesome as it would be from a chase perspective to have that solution verify, I don't think it's likely.

The euro is t far from that actually … with these height falls expected easily see another surface low pressure develop . Time spc upgrade , this one large enhanced risk for a day 3 threat

 

[Casuarina Head]

Forgot to look at UK met, yeah UKmet is with NAM suite, also Euro isn't as bad on second look, has some good soundings in pocketed areas, but it's also a global model so more interested in mesoscale models at this stage.
Edit: Also 18z GFS is good for areas about south of OH river, has a potentially significant event there, but doesn't have northern extent like NAM.

The problem is that the latest (00Z) EPS has trended toward more unidirectional flow with height, owing to a more amplified solution, and thereby constricts the tornado-friendly parameter space significantly, especially toward the northern half of the 30% hatched area. I am starting to think that the greatest threat on Wednesday will be wind-related rather than attributable to widespread, discrete, long-tracked tornadoes. If Wednesday were juxtaposed with a broader-based, lower-amplitude solution and greater curvature with height, then a significant tornado outbreak would be likely, but as of now I don’t see the basis for more than an ENH in the tornado department (higher in the wind department, obviously).

 

[tennessee storm chaser]

The problem is that the latest (00Z) EPS has trended toward more unidirectional flow with height, owing to a more amplified solution, and thereby constricts the tornado-friendly parameter space significantly, especially toward the northern half of the 30% hatched area. I am starting to think that the greatest threat on Wednesday will be wind-related rather than attributable to widespread, discrete, long-tracked tornadoes. If Wednesday were juxtaposed with a broader-based, lower-amplitude solution and greater curvature with height, then a significant tornado outbreak would be likely, but as of now I don’t see the basis for more than an ENH in the tornado department (higher in the wind department, obviously).

Is Epps better long range forecasting vs short range ,? Say within 48 hours … like see how the Nam gets in better range for a discount a tornado type event or even outbreak .