Severe WX April 3rd-5th, 2023 (South, Southeast, Ohio Valley)

[Clancy]

CIPS for 1+ SVR report from 12Z 04/03-04/06.

 

[Casuarina Head]

Wow. Ouch !

To be fair, when’s the last time a similar D7 ensemble mean verified? At the very least I think the aerial coverage of strong instability will contract significantly, once closer to D1. I am still waiting to see how well Friday’s upcoming event matches runs from D4 and earlier. Of course, modelled projections verified quite well for 24 March, so perhaps we are finally abandoning the tendency to underperform relative to projections. And of course, before anyone else mentions it, I may as well point out the numerological coincidences:

Tuesday, 4 Apr 2023
Wednesday, 3 Apr 1974

Fiftieth anniversary to boot. Not that next Tuesday will come even remotely close, but still...after all, 27 Apr 2011 was on a Wednesday + seven years...

 

[tennessee storm chaser]

To be fair, when’s the last time a similar D7 ensemble mean verified? At the very least I think the aerial coverage of strong instability will contract significantly, once closer to D1. I am still waiting to see how well Friday’s upcoming event matches runs from D4 and earlier. Of course, modelled projections verified quite well for 24 March, so perhaps we are finally abandoning the tendency to underperform relative to projections. And of course, before anyone else mentions it, I may as well point out the numerological coincidences:

Tuesday, 4 Apr 2023
Wednesday, 3 Apr 1974

Fiftieth anniversary to boot. Not that next Tuesday will come even remotely close, but still...after all, 27 Apr 2011 was on a Wednesday + seven years...

April 74 did have similar slp track like one being modeled thus far for next Tuesday , scary similar … the position trajectory of the trough similar . But slp seems modeled be more intense …. See how it plays out

 

[Edith]

To be fair, when’s the last time a similar D7 ensemble mean verified? At the very least I think the aerial coverage of strong instability will contract significantly, once closer to D1. I am still waiting to see how well Friday’s upcoming event matches runs from D4 and earlier. Of course, modelled projections verified quite well for 24 March, so perhaps we are finally abandoning the tendency to underperform relative to projections. And of course, before anyone else mentions it, I may as well point out the numerological coincidences:

Tuesday, 4 Apr 2023
Wednesday, 3 Apr 1974

Fiftieth anniversary to boot. Not that next Tuesday will come even remotely close, but still...after all, 27 Apr 2011 was on a Wednesday + seven years...

Frankly 1974 instantly came to mind. This has so much potential it’s frightening. I do realize a lot can change but this has outbreak written all over it…

 

[Casuarina Head]

April 74 did have similar slp track like one being modeled thus far for next Tuesday , scary similar … the position trajectory of the trough similar . But slp seems modeled be more intense …. See how it plays out

Looking at Corfidi et al. (2010), one can see that 3 Apr 1974 featured a much broader warm sector, at least longitudinally. The contours indicate dewpoints of 56°, 62°, and 68°F, respectively:

By contrast, the 00Z ECMWF’s projection for 18Z next Tuesday:

As of 18Z on 3 Apr 1974, surface observations indicated that dew points of 62°F extended eastward and were present along the NC–VA border. The EC indicates that dew points of ≥ 60°F will extend no farther northeast than SC by 18Z Tuesday.

Bottom line: a deeper surface low, but a much narrower, if not lower-quality, warm sector.

 

[Casuarina Head]

^ I might also add that the very warm subtropical Northwestern Atlantic, a staple since 2012, would tend to reinforce surface-based high pressure over the Southeastern U.S. and thereby constrict the warm sector via cold-air damming. This alone would greatly reduce the already-low likelihood of a 1974-style repeat, simply by reducing the aerial coverage of richer moisture and/or instability. By contrast, a colder NW ATL would foster southerly and/or southwesterly rather than northerly and/or northeasterly flow over the Southeast, enlarging the warm sector.

 

[CheeselandSkies]

^ I might also add that the very warm subtropical Northwestern Atlantic, a staple since 2012, would tend to reinforce surface-based high pressure over the Southeastern U.S. and thereby constrict the warm sector via cold-air damming. This alone would greatly reduce the already-low likelihood of a 1974-style repeat, simply by reducing the aerial coverage of richer moisture and/or instability. By contrast, a colder NW ATL would foster southerly and/or southwesterly rather than northerly and/or northeasterly flow over the Southeast, enlarging the warm sector.

Would the clockwise flow around the ridge not promote southerly winds over the western edge, as in the eastern CONUS?

 

[Edith]

Looking at Corfidi et al. (2010), one can see that 3 Apr 1974 featured a much broader warm sector, at least longitudinally. The contours indicate dewpoints of 56°, 62°, and 68°F, respectively:

By contrast, the 00Z ECMWF’s projection for 18Z next Tuesday:

As of 18Z on 3 Apr 1974, surface observations indicated that dew points of 62°F extended eastward and were present along the NC–VA border. The EC indicates that dew points of ≥ 60°F will extend no farther northeast than SC by 18Z Tuesday.

Bottom line: a deeper surface low, but a much narrower, if not lower-quality, warm sector.

I understand your analysis calling it a more narrow warm sector than 1974 however this is still quite a large warm sector overall setting aside the comparison. I could see less of a coverage area in regards to tornadoes but not necessarily severity of the output in the available warm sector

 

[Edith]

Would the clockwise flow around the ridge not promote southerly winds over the western edge, as in the eastern CONUS?

This was my thoughts as well. I don’t see how he gets there honestly. If anything I see these dew points going higher as we get closer

 

[Casuarina Head]

Would the clockwise flow around the ridge not promote southerly winds over the western edge, as in the eastern CONUS?

My point is that the ridge-axis extends farther inland over the Southeast than it would if the SST off the Eastern Seaboard were colder, leading to more of a northerly component.

 

[Casuarina Head]

I understand your analysis calling it a more narrow warm sector than 1974 however this is still quite a large warm sector overall setting aside the comparison. I could see less of a coverage area in regards to tornadoes but not necessarily severity of the output in the available warm sector

The lesser aerial coverage could lead to either a) a messier warm sector or b) an isolated-but-intense, long-lived supercell rather than numerous supercells.

Bottom line: it’s still far too early to make too many direct comparisons with a once-in-a-lifetime outbreak.

 

[Edith]

The lesser aerial coverage could lead to either a) a messier warm sector or b) an isolated-but-intense, long-lived supercell rather than numerous supercells.

Bottom line: it’s still far too early to make too many direct comparisons with a once-in-a-lifetime outbreak.

I agree it’s early but personally I see the preverbal writing on the wall. Also if this verified as is I would bet the house you get more than one supercell in that warm sector. Wishful thinking there in my view. Messy warm sector totally possible

 

[ColdFront]

The lesser aerial coverage could lead to either a) a messier warm sector or b) an isolated-but-intense, long-lived supercell rather than numerous supercells.

Bottom line: it’s still far too early to make too many direct comparisons with a once-in-a-lifetime outbreak.

I’m not sure we know exactly how common those very high end outbreaks actually are, but I bet you there was someone on earth that was alive through the 1932 Dixie, 1974, and 2011 outbreaks.

I would argue Enigma, Dixie 1932, Palm Sunday, April 1974, and April 27,2011 are all qualifying as the upper echelon of outbreaks. What kind of time scale they are on is up for debate.

 

[MichelleH]

I’m not sure we know exactly how common often those very high end outbreaks actually are, but I bet you there was someone on earth that was alive through the 1932 Dixie, 1974, and 2011 outbreaks.

I would argue Enigma, Dixie 1932, Palm Sunday, April 1974, and April 27,2011 are all qualifying has the upper echelon of outbreaks. What kind of time scale they are on is up for debate.

My grandmother passed away in 2015, but she did live through the 3/21/32, 4/3/74 and 4/27/11 outbreaks. All three directly affected our county. I have lived through 4/3/74 and 4/27/11 and if I live until my 80's, I can almost guarantee I will live through another "once-in-a-lifetime" outbreak.

 

[Penitentes]

Saint Louis radar site (KLSX) will be down for the 3/31 event and this one. Sigh.

National Weather Service St. Louis radar update delayed due to potential severe weather

The National Weather Service has announced the upgrade would be delayed until April 6.

www.kmov.com

 

[atrainguy]

I’m not sure we know exactly how common those very high end outbreaks actually are, but I bet you there was someone on earth that was alive through the 1932 Dixie, 1974, and 2011 outbreaks.

I would argue Enigma, Dixie 1932, Palm Sunday, April 1974, and April 27,2011 are all qualifying as the upper echelon of outbreaks. What kind of time scale they are on is up for debate.

Would Easter 2020 also count as a Super Outbreak, or does the lower amount of violent tornadoes make it undeserving of that status? IIRC it's the 3rd largest outbreak recorded in terms of the number of tornadoes in 24 hours, and it happened less than a decade after the largest ever recorded.

 

[ColdFront]

Would Easter 2020 also count as a Super Outbreak, or does the lower amount of violent tornadoes make it undeserving of that status? IIRC it's the 3rd largest outbreak recorded in terms of the number of tornadoes in 24 hours, and it happened less than a decade after the largest ever recorded.

Nailed it. It was a high end outbreak, but it wasn’t in the same stratosphere as the others listed. If anyone disagrees though I’m still learning and would love to hear counter points

 

[TheSuckZone]

Saint Louis radar site (KLSX) will be down for the 3/31 event and this one. Sigh.

National Weather Service St. Louis radar update delayed due to potential severe weather

The National Weather Service has announced the upgrade would be delayed until April 6.

www.kmov.com

Why am I not surprised?

 

[cincywx]

Nailed it. It was a high end outbreak, but it wasn’t in the same stratosphere as the others listed. If anyone disagrees though I’m still learning and would love to hear counter points

correct. a sizeable majority of the TORs were weak that day, and i would bet a great deal of them would have flown under the radar (no pun intended) prior to the nexrad era.

having said that, 120+ tornadoes in <=24 hours will always be absolutely nuts.

 

[Casuarina Head]

This was my thoughts as well. I don’t see how he gets there honestly. If anything I see these dew points going higher as we get closer

As the above image illustrates, a lot of ground will need to be covered. Could it be? It might, but much needs to change on future runs.

This could still be a major event, but the bigger the warm sector, the lesser the chance of a “failure”-based mode (i.e., messy convection).