Tornado"Super Outbreak" - Is it Possible Again?

[Chris Lott]

Does anyone think there will ever be another outbreak like the jumbo outbreak of April 3-4, 1974? I'm reading a book about extreme weather and it talks about the 148 tornadoes that occurred in an 18 hour period from Illinois to Alabama and east to Virginia. This outbreak wa pretty phenomenal. Or do you think we will ever see another event like Moore, Oklahoma? What are your thoughts.

 

[Robert Dewey]

An outbreak of that magnitude WILL occur again, the question is; when and where? Some have said that the Super Outbreak is a 500 year event, or perhaps even a millenium event. Since detailed records don't go back that far, it's impossible to say for sure.

 

[Jeff Snyder]

Re: Tornado"Super Outbreak" - Is it Possible Again

Does anyone think there will ever be another outbreak like the jumbo outbreak of April 3-4, 1974? I'm reading a book about extreme weather and it talks about the 148 tornadoes that occurred in an 18 hour period from Illinois to Alabama and east to Virginia. This outbreak wa pretty phenomenal. Or do you think we will ever see another event like Moore, Oklahoma? What are your thoughts.

I know we'll see another "Super Outbreak" caliber event. In fact, I seriously expected the May 30th 2004 outbreak to surpass that mark. Actually, the May 29-30 2-day period had MORE tornadoes than the April 3-4 1974 2-day period did. Obviously, we're comparing 42-48 hours to 18 hours (Super Outbreak), but the two-day record goes to the 5-29/30-2004 outbreak.

The 5-3-99 Bridgecreek/Moore tornado wasn't really a once-in-a-century type of event... There usually are several long-track, strong/violent tornadoes each year. The 5-3-99 F5 just happened to traverse through a majorly populated area. I'm sure there are more F4/F5 tornadoes each year -- they just don't hit anything (or they don't hit anything while they are producing winds in the >225mph range). This shouldn't minimize the fact that the Moore tornado was the strongest observed on radar, but who knows how many other tornadoes have stronger winds? Heck, maybe the Hallam tornado has winds >350mph for a short while? Who knows! That's the exciting thing about all of this -- the next observation of a tornado may reveal something entirely new, something entirely not previously understood about tornadoes.

 

[JP Santiago]

Was it more a case of having the perfect set of conditions for tornadogenesis during the Super Outbreak or was it more that the usual conditions that are seen in smaller storms more frequently were present over a larger area, resulting in a broad outbreak?

 

[Fred Gossage]

It was a matter of having all the perfect conditions juxtaposed exactly right...........over such a widespread area.......

 

[Robert Dewey]

I guess if we are talking NUMBERS only, then yes, certain events have gotten pretty close to the Super Outbreak. But, I think it's also important to look at intensity. The majority of the tornadoes in the Super Outbreak were strong to violent (there were 91 strong to violent tornadoes (F2-F5)). When you look at the intensity factored in with the number of tornadoes, this outbreak is quite unique.

 

[Bryce Stone]

Gotta keep in mind, though, that we only have very detailed records for about the last 100 years or so. In that time we have seen several major events, like the Tri-State event of 1925, the Waco event, the Super Outbreak, the Moore event, ect., ect., ect.

With an ever-increasing population in the U.S., I'd say it is almost a certainty that we will see major tornado events about every 10-20 years. Also, how do we know that the Super Outbreak is really so rare? My thinking is that since we haven't been keeping records for very long (in a relative sense), we can't really say how often major outbreaks occur.

I do agree that the Super Outbreak is unique due to the intensity of tornadoes it spawned.

 

[Jeff Snyder]

When you look at the intensity factored in with the number of tornadoes, this outbreak is quite unique.

It was quite unique, but just keep in mind that this was well before there was a good understanding of the impact of structural integrity on damage production. My hunch is that few of the violent tornadoes were really violent tornadoes as they'd be rated today. It seems to me that any tornado that ripped apart a house was rated >F3 in that day, regardless of the structural strength of those houses... Tim Marshall showed that some of the La Plata, MD, damage that was preliminarily rated F4-F5 was actually more like F1-F2 owing to the fact that some of the houses/structures were very poorly attached to their foundations ("sliders")... I'm not trying to take away from the uniqueness of the event, but I'd say that if that event happened again today, we'd see FAR fewer tornadoes rated in the strong/violent range.

 

[brody_clifton]

I believe the large scale middle latitude cyclone responsible for the Super Outbreak was extremely unique indeed. Though it is impossible to calculate an accurate probability of an event of this magitude to occur during any certain span of time, due to the lack of scientific observations of storm systems over the past millenium, I think it is a reasonable educated guess to expect this type of event to occur roughly once in a period on the order of 100s of years.
But who knows, maybe this has already happened 5 times this century and we just didn't have the technology to realize it, since there were no (useful) weather satellites prior to 1960.
However, look at the gigantic propotions of the synoptic features of this event. An active 'pressure cooker' type warm sector over generally the entire US east of the Mississippi river (with the exception of FL, the southern half of the Gulf states, and areas north of southern Michigan. In order for this to happen, this entire area had to be capped with SW US desert air from the previous couple of days' events. And the strong upper level energy and associated surface boundaries neccessary to provide lift had to approach and then cover most of this large area as well in order for the cap to even be broken, it was so strong in most of the affected areas. I believe, from what I've read, that the capping inversion itself was what was so very rare with this storm. With other systems in the past that have (somewhat) approached the size of this storm system, usually there was a relatively small area, compared to that of the SO, that was capped just enough to suppress strong convection until max heating but also allow it at max heating. In other large scale systems like this, which usually come across the US during the first half of spring, the areas in the northern sectors are generally weakly or non-capped allowing for large MCS type precip shields to develop early, and areas in the far southern sectors are generally too strongly capped to allow for deep convection. But of course, it takes a storm system as large as this one was to be able to accomplish what it did over as large an area.
What really makes me really understand how huge this storm was is the satellite image of it, which I have kept as my desktop wallpaper for a while now. I've compared it to the 'big' systems we've had cross the conus this season, and none of them even came close. The 5/4/03 outbreak was somewhat close to it in scale, and there's no way to tell how the '74 SO compares with the 3/18/25 outbreak, but as of now the SO takes the prize for the largest observed in history.

Edit: But not even the 1974 Super Outbreak compares in intensity to the 4/11/65 Palm Sunday Outbreak in the Upper Midwest. I mean, 135 kt. observed 500mb jet streak (vs 120kt max observed 04/03/74), that is too insane!! What do you all think the odds are of this happening again in the next 50 years?

 

[afischer]

A while back, I came across a 500mb chart from the morning of 4/11/65 and noted one of the RAOBs showing the 135kt wind max that was mentioned... I thought it was in error! I don't know where the wind max was relative to the time and location of the tornadic supercells... but what really blows my mind is that convection can even remain upright with such tremendous deep shear. Even a 100-kt wind at 500mb would be crazy.

The tri-state tornado had a mean forward speed of 73kts I believe, which would mean (one would think) 90+kts @ 500mb that day too.

These were both events that occurred in early spring when one wouldn't expect CAPE values that were too outrageous... though I guess the difference between 2500 CAPE and 4000 CAPE is maybe not significant in the whole realm of things. Maybe the sheer strength of the dynamics (i.e. upper difluence) common w/ prolific outbreaks helps to sustain updrafts?

In relation, the supercells on 5-4-03 had ~3000 CAPE vs. ~70kts at 500mb. While they weren't quick to mature, they didn't take too long to turn supercellular and had no trouble sustaining themselves and producing long-track tornadoes despite very strong deep shear.

 

[Shane Adams]

Sure it is. No one knows what the atmosphere is capable of until it happens.

Aside...as far as 5-3-99, that event remains unique in that there were several isolated, tornadic storms in relative close proximity to one another for many hours. There were multiple locations in OK that day which were hit by multiple tornadoes. I believe that for sheer concentration and prolific tornadic production, May 3, 1999 is second to none.

 

[Stuart Robinson]

This date was very rare in the UK

Largest Tornado Outbreak
The largest tornado outbreak in Britain is also the largest tornado outbreak known anywhere in Europe. On November 21, 1981, 105 tornadoes were spawned by a cold front in the space of 5.25 hours. Excepting Derbyshire, every county in a triangular area from Gwynedd to Humberside to Essex was hit by at least one tornado, while Norfolk was hit by at least 13. Very fortunately most tornadoes were short-lived and also weak (the strongest was around T5 on the TORRO Tornado Scale) and no deaths occurred.

 

[Alex Lamers]

November 10, 2002 also jumps to mind. Here are comparisons...

Nov. 10 2002:
* 70 Tornadoes
* 596.4 miles of total path length
* 10 Killer Tornadoes
* 2 >50 mile path length tornadoes
* 34% of all tornadoes were strong or violent
* Spanned 12 states

Super Outbreak:
* 147 tornadoes
* 2490 miles of total path length
* 48 killer tornadoes
* 8 >50 mile path length tornadoes
* 66% of all tornadoes were strong or violent
* Spanned 13 states

CLEARLY there is no comparison! May 30 2004 and some of the others also don't come close. I would say it is probably a once in a 200 yr event although I would be interested to know if those rare events are becoming more frequent like other types of extreme weather. Seems like the globe is getting more and more extremes...and less near-average conditions. Well in that case, perhaps we will see another one similar to the super outbreak in our life times.

...Alex Lamers...

 

[Jeremy Lemanski]

Interesting question in regards to the super outbreak, When, and yes it will happen again, the super outbreak is surpassed in numbers by another outbreak, what will it be called? As of now, all tornado outbreaks are compared to the super outbreak, or sometimes palm sunday 1 and 2. Do we call it Super outbreak two? When this outbreak occurs, will it lessen the sig. of the 1974 outbreak?

This is the problem, at least to me, in calling something be such a strong name. The word SUPER screams that it was the biggest tornado outbreak in history, yet our history in weather really goes back what, 40-50 years? Some noteable tornados occured before this time which i think could have occured during Large outbreaks:

The tri state tornado, Do we know how many other tornados occured on this day?

April 5-6 1936, this likely was a large outbreak, based on Tupelo and gainsville being struck by sig. tornados on back to back days, only about 12 hours apart.

New Richmond Wis, 1899.

Those are just some thoughts to ponder, as we sit and wait for the next super outbreak.

 

[Fred Gossage]

Another outbreak to note........especially for Alabamians..... is the March 21, 1932 event, which is actually Alabama's worst tornado event to date. EIGHT F4 tornadoes occurred during this event. There's no telling how many other states were slammed.