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

[andyhb]

To clarify: I meant that so far 2022 has not featured at least one “clean, low-amplitude, polar-jet-only” system, despite having generated several outbreaks. (The winter of 2021 did feature at least one system that met this description: the major outbreak on 10–11 December.) My point is that I would expect a robust winter-/springtime -PDO/-ENSO/+TNI to yield at least one “clean, low-amplitude, polar-jet-only” system to date in 2022—a large-scale synoptic system that is unaffected by blocking and subtropical interference.

Oh will you please just stop with this already? It is getting tiresome.

We had over 200 tornadoes in March (the Winterset IA event was a polar jet event), and the event on April 5th was indeed a low amplitude disturbance.

 

[Fred Gossage]

Oh will you please just stop with this already? It is getting tiresome.

We had over 200 tornadoes in March (the Winterset IA event was a polar jet event), and the event on April 5th was indeed a low amplitude disturbance.

Add to that the fact that the past several systems have actually trended lower amplitude as we have gotten closer. Both of the March outbreak troughs initially were modeled to be fully cutoff upper lows in the medium range and then trended toward being amplified but open and progressive troughs... and then the system this week started as a low amplitude but consolidated trough and trended disjointed and a bit sheared.

 

[andyhb]

Add to that the fact that the past several systems have actually trended lower amplitude as we have gotten closer. Both of the March outbreak troughs initially were modeled to be fully cutoff upper lows in the medium range and then trended toward being amplified but open and progressive troughs... and then the system this week started as a low amplitude but consolidated trough and trended disjointed and a bit sheared.

This, that TX event on 3/21 was looking like a mess of a closed low until a few days out when the trough began to open up again in guidance, and we saw the results. Is this trough higher amplitude? Yes. Is it also favorable for tornadic supercells especially considering the dryline placement/orientation? Also yes. Is it driven by the STJ or interfered with because of it? That's a negative.

 

[andyhb]

For this upcoming system, I get the feeling like some surprises are yet in store and Wednesday might be the day that stands to gain the most in terms of significant severe potential because of them. Not just from a moisture/instability standpoint, but because that is likely the day the trough will eject from the west. Should we see signs of more deamplification (and/or slowing) of the pattern leading into Wednesday, there is a relatively high likelihood that significant severe wx will manifest, potentially over a pretty large area.

 

[Shakespeare 2016]

For this upcoming system, I get the feeling like some surprises are yet in store and Wednesday might be the day that stands to gain the most in terms of significant severe potential because of them. Not just from a moisture/instability standpoint, but because that is likely the day the trough will eject from the west. Should we see signs of more deamplification (and/or slowing) of the pattern leading into Wednesday, there is a relatively high likelihood that significant severe wx will manifest, potentially over a pretty large area.

A little off topic but do you almost have your PhD?

 

[KevinH]

I think it's probably safe for you to cut the timeframe for this thread off at the 14th. I don't think a threat with this wave would extend beyond Thursday/Thursday night unless things were to radically slow down. You may also want to do a cutoff like that since there is a potentially increasing signal for another system behind this one over the weekend if this one lifts out correctly.

Remove 15th from title thread: DONE.

Someone else can start the thread for the (potential) event around the 16th lol

 

[Fred Gossage]

Remove 15th from title thread: DONE.

Someone else can start the thread for the (potential) event around the 16th lol

Too soon. I just wanted to make sure that if that thing did look like it would really happen, that we'd have the discussions separated. It will be a completely different and unrelated system. Thanks man!

 

[CheeselandSkies]

For this upcoming system, I get the feeling like some surprises are yet in store and Wednesday might be the day that stands to gain the most in terms of significant severe potential because of them. Not just from a moisture/instability standpoint, but because that is likely the day the trough will eject from the west. Should we see signs of more deamplification (and/or slowing) of the pattern leading into Wednesday, there is a relatively high likelihood that significant severe wx will manifest, potentially over a pretty large area.

Thanks, Andy. Was hoping you'd chime in with your thoughts either here, on AmWx or Stormtrack.

 

[CheeselandSkies]

Latest run of Fred's favorite model forecast sounding over Kansas on Tuesday evening...this makes more sense although with supercell composite approaching 40, 3KM EHI almost 13.5, STP over 10 and fixed layer STP of almost 8, surprising it isn't a "PDS" TOR. T/Td spreads a little too large is the only thing I can think of, although LCL height doesn't look like an event-breaker. There's also a slight inversion a little above 850mb, but you *need* some degree of capping so you don't get instant squall line, right?...

For my area, if I'm looking for a local chase on Wednesday, the GFS is now too fast with the front sweeping through around 12Z Wednesday. However this could be its progressive bias at play.

 

[Shakespeare 2016]

Latest run of Fred's favorite model forecast sounding over Kansas on Tuesday evening...this makes more sense although with supercell composite approaching 40, 3KM EHI almost 13.5, STP over 10 and fixed layer STP of almost 8, surprising it isn't a "PDS" TOR. T/Td spreads a little too large is the only thing I can think of, although LCL height doesn't look like an event-breaker. There's also a slight inversion a little above 850mb, but you *need* some degree of capping so you don't get instant squall line, right?...

For my area, if I'm looking for a local chase on Wednesday, the GFS is now too fast with the front sweeping through around 12Z Wednesday. However this could be its progressive bias at play.

I am not the best with reading charts and graphs but those parameters seem really high.

 

[Fred Gossage]

Latest run of Fred's favorite model forecast sounding over Kansas on Tuesday evening...this makes more sense although with supercell composite approaching 40, 3KM EHI almost 13.5, STP over 10 and fixed layer STP of almost 8, surprising it isn't a "PDS" TOR. T/Td spreads a little too large is the only thing I can think of, although LCL height doesn't look like an event-breaker. There's also a slight inversion a little above 850mb, but you *need* some degree of capping so you don't get instant squall line, right?...

For my area, if I'm looking for a local chase on Wednesday, the GFS is now too fast with the front sweeping through around 12Z Wednesday. However this could be its progressive bias at play.

That's all the operational GFS even is anymore....

 

[Bevo]

Looking at potentially 3 back to back days of nasty weather in the DFW metro with this one. Yuck.
And we just bought a house last year with a 15 year old roof.

 

[Todd]

Being in Missouri I have a great deal of interest in what could happen Monday, Tuesday, and Wednesday regarding what SPC is forecasting.

 

[Casuarina Head]

12z GFS, Canadian, and GFS ensembles have trended toward the system being a bit deeper and heights being lower east of the MS River overnight Wednesday night. There is significantly more cyclonic curvature aloft with the trough Wednesday night on the 12Z GEFS compared to previous runs too. The overall look of the data today would increase the overall Wednesday afternoon to Thursday morning risk and also elevate the chances of it extending east of the MS River Wednesday night into Thursday morning.

The most recent EPS runs also reflect this trend. The main problem on Wednesday is that the trend toward a deeper, “curved” disturbance also implies that the best UL and LL dynamics will be dislocated during peak diurnal heating. For instance, by 00Z on Thursday the strongest H5 winds and greatest bulk shear are over eastern OK/KS and western AR/MO, whereas the strongest LL and surface winds (to not mention the highest dew points) are situated closer to the Mississippi River. Certainly, the surface low is deeper, but the greater amplification offsets that to a degree, so that subtle low-level boundaries will be needed to serve as foci for upper-end SVR. A lower-amplitude trough would not end up with this kind of problem.

 

[tennessee storm chaser]

Spc already calling for super cells with tornadoes late Wednesday afternoon evening for mid south Memphis region. Sure timing will need to be tuned . Pretty strong wording for this far out

 

[JPWX]

Spc already calling for super cells with tornadoes late Wednesday afternoon evening for mid south Memphis region. Sure timing will need to be tuned . Pretty strong wording for this far out

I noticed too that in NWS Memphis morning discussion they say: "many parameters point to a severe weather outbreak centered somewhere over northern Louisiana, Arkansas, Missouri." Given that Memphis office is usually conservative, that raises eyebrows.

 

[tennessee storm chaser]

I noticed too that in NWS Memphis morning discussion they say: "many parameters point to a severe weather outbreak centered somewhere over northern Louisiana, Arkansas, Missouri." Given that Memphis office is usually conservative, that raises eyebrows.

What’s even more intriguing, the forecaster wrote that up is probably the most conservative forecaster in our region . Great forecaster but conservative side

 

[Fred Gossage]

The most recent EPS runs also reflect this trend. The main problem on Wednesday is that the trend toward a deeper, “curved” disturbance also implies that the best UL and LL dynamics will be dislocated during peak diurnal heating. For instance, by 00Z on Thursday the strongest H5 winds and greatest bulk shear are over eastern OK/KS and western AR/MO, whereas the strongest LL and surface winds (to not mention the highest dew points) are situated closer to the Mississippi River. Certainly, the surface low is deeper, but the greater amplification offsets that to a degree, so that subtle low-level boundaries will be needed to serve as foci for upper-end SVR. A lower-amplitude trough would not end up with this kind of problem.

That increased cyclonic curvature aloft means positive vorticity advection and height falls aloft spreading out over the open warm sector where the strongest low-level winds are. That means large scale ascent is overspreading that open warm sector to the east. Most tornado outbreaks, especially the ones east of the Plains, do not happen under the core of the strongest upper winds. They happen to the right of the upper jet in the cyclonic curvature out over the warm sector, even if that's the right front quadrant of the upper jet sometimes. When the jet streak is cyclonically curved, the textbook four quadrant schematic breaks down some, and you end up getting some of the divergence to leak into the right-front quadrant, even though it is usually marked by subsidence in the four-quadrant model of a straight jet streak. Very rarely, if even ever, do large-scale tornado events east of the Plains happen directly under the core of the strongest upper-level winds. What you see modeled in the EPS is how significant tornado events occur in the open warm sector in the MS/TN/OH Valleys.

 

[CheeselandSkies]

First PDS sounding I've found on the GFS in the lead-up to this event, over southwest Iowa for Tuesday. Already put in to duck out of work early Tuesday and take Wednesday off.

 

[Fred Gossage]

GFS/GEFS/Euro op trend for today has been for the system to be progressively more occluded as it approaches areas east of the MS River Wednesdsay overnight into Thursday morning. If this is accurate, this would definitely keep the higher threat near and west of the MS River. There is still variation in the handling of the trough, and we will likely see that for a couple more days until the upper energy with the wave starts getting onshore. It would not surprise me at all if the higher risk is west of the MS River, but until this is the evolution that fully locks in, the door is open for there to be a risk that extends eastward with time.