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.
 
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.
 
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.
 
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?
 
It was a matter of having all the perfect conditions juxtaposed exactly right...........over such a widespread area.......
 
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.
 
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.
 
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.
 
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?
 
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.
 
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.
 
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.
 
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...
 
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.
 
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.
 
Yes, it will eventually happen again. We don't yet have enough weather records to determine the odds of such an event however. We don't know if it's a once in 100 years thing, once in 500 years or once in a thousand years type of event.

I will say November 10, 2002 did come close to pushing the Apr 3-4 outbreak. Had the middle portion of the outbreak been as active as the NRN and SRN portions, I think there would have been a smiliar total tornado count. If you recall, on Nov 10, 2002, most of SRN IN, SRN OH and all of KY didn't get much (squall line vs isolated sups), whereas as they did in 1974. This was the main difference.

Another date from 2002 that could have been HUGE was April 28th. There were 35 tornadoes anyway, including the La Plata, MD F4. But there were so many supercells that day that didn't produce tornadoes. There were at least 3 waves of supercells that moved through my area, that to my knowledge, never produced a single tornado. Had the number of storms to produce tornadoes that day been higher, it could have been one Jim Dandy of an event.

-George
 
One thing unusual about the Super Outbreak was how many populated areas were hit by strong/violent tornadoes. This outbreak wasn't just in the open cornfields. Major population centers were hit (some more than once). Truly an incredible outbreak.
 
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?

You betcha! I think there will be a bunch. In geological years we've only scratched the surface. I hope to chase a few of them.

On the other hand can you imagine chasing under a 135mph 500mb jet?!! Think of the storm speeds. With widespread storms and high density tornadoes it could be extremely difficult and dangerous to chase such a situation. Reminds me of a high risk I chased with Gene Moore in the TX/OK panhandle area about 5 years ago. All the storms were moving 60 to 70mph. I think there may have been a few over 80 or 90. We set up in front of them and there wasn't much to see - just a gray sky. In just minutes a raging "front" appeared with electrified anvils causing coronal discharges on our scanner. Gene got shocked. The storm rushed upon us and we noted a couple areas of rotation in the mess. We 180'd and I punched my Tahoe (just tuned) to maximum acceleration. Throttle retard at 100 and I needed everthing as the winds nearly blew us off the road trying to escape. Gene noted a spinning tornadic vortex right off our right side slightly behind us trying to eat us. We finally pulled away and took shelter behind a metal shed. 13 telephone poles were blow over or broken at our previous position. I'm just glad it didn't happen when I was driving so fast during my escape. Anyway you get the idea.
 
The thing is, if another similar event occurs, it will probably be in the same general area. It seems that the area of the nation most prone to these HUGE events are MO, IL, AR, TN, MS, AL, GA, KY, IN, OH, etc. Most of the really historically huge outbreaks have occurred in those areas or some part of those areas. Therefore I have no reason to think future ones will not behave similarly.

Much of that region is not particularly well suited to chasing, though some areas are obviously better than others.

The other thing is, as far as chasing, an outbreak such as April 3-4, 1974 would be the LAST type of setup you'd want to chase. Lines of supercells moving at 60 mph would be no joy. LOL. Also, a good number of those tornadoes happened after dark, especially those in SRN KY, TN, and AL. Factor that into the poor chase terrain and you can see where I'm going.....not a pretty picture.

I think the Super Outbreak (and those in the future like it, whenever they take place) will be more important historically than they will for actual chasing importance. Certainly, an event like that is big news and will be talked about for years. I've often regretted not being alive then just because I missed the experience of living through such a massive and unprecedented event (I didn't enter this world until 1977). But I doubt many chasers would have any interest at all in chasing such an event.

In contrast, the Apr 10, 1979 outbreak only produced 11 tornadoes (or thereabouts). But most were huge and some were almost like giant sculptures begging to be photographed. I'm not sure about the forward speed of those storms, but everything else was almost perfect. If the storm speed was reasonable, that outbreak would have been a chasers dream come true, whereas Apr 3, 1974 would have been a nightmare. Another date that comes to mind is Apr 26, 1991. That date won't go down into the recod books as being a Super Outbreak. But for chasing, it was awesome. Again, I'm not sure about the storm speeds. Being early April, they were probably a bit higher than perfect. But still, though the number of tornadoes was far less, they happened over some of the greatest chase terrain in the world. And they occurred from a smaller number of storms.

I think the best outbreak days for chasing are the smaller days where you only have 2-3 supercells, but highly cyclic ones. If this can take place in an area that's flat and with few trees, has good road networks and if the storms are moving at tolerable speeds, then you have the perfect outbreak for chasers. Of course in the day of the chaser convergence, that might spoil an otherwise perfect event. LOL. In that regard, spreading people out over a wide area would be the only beneficial thing about having a major outbreak.

The point in mentioning this is that we get those kinds of days far more often. And they are likely far more rewarding to the chaser than a 'super outbreak" in which chaos reigns supreme. At least I think most chasers would agree.
 
The thing is, if another similar event occurs, it will probably be in the same general area. It seems that the area of the nation most prone to these HUGE events are MO, IL, AR, TN, MS, AL, GA, KY, IN, OH, etc. Most of the really historically huge outbreaks have occurred in those areas or some part of those areas. Therefore I have no reason to think future ones will not behave similarly.

Much of that region is not particularly well suited to chasing, though some areas are obviously better than others.

The other thing is, as far as chasing, an outbreak such as April 3-4, 1974 would be the LAST type of setup you'd want to chase. Lines of supercells moving at 60 mph would be no joy. LOL. Also, a good number of those tornadoes happened after dark, especially those in SRN KY, TN, and AL. Factor that into the poor chase terrain and you can see where I'm going.....not a pretty picture.

I think the Super Outbreak (and those in the future like it, whenever they take place) will be more important historically than they will for actual chasing importance. Certainly, an event like that is big news and will be talked about for years. I've often regretted not being alive then just because I missed the experience of living through such a massive and unprecedented event (I didn't enter this world until 1977). But I doubt many chasers would have any interest at all in chasing such an event.

In contrast, the Apr 10, 1979 outbreak only produced 11 tornadoes (or thereabouts). But most were huge and some were almost like giant sculptures begging to be photographed. I'm not sure about the forward speed of those storms, but everything else was almost perfect. If the storm speed was reasonable, that outbreak would have been a chasers dream come true, whereas Apr 3, 1974 would have been a nightmare. Another date that comes to mind is Apr 26, 1991. That date won't go down into the recod books as being a Super Outbreak. But for chasing, it was awesome. Again, I'm not sure about the storm speeds. Being early April, they were probably a bit higher than perfect. But still, though the number of tornadoes was far less, they happened over some of the greatest chase terrain in the world. And they occurred from a smaller number of storms.

I think the best outbreak days for chasing are the smaller days where you only have 2-3 supercells, but highly cyclic ones.

The point in mentioning this is that we get those kinds of days far more often. And they are likely far more rewarding to the chaser than a 'super outbreak" in which chaos reigns supreme. At least I think most chasers would agree.

Yes, chasing an outbreak such as the super outbreak would be dangerous and likely unrewarding. The tornadoes would be moving at 40-60mph, likely be rainwrapped, and embbeded in a massive squall line. Also, as you stated in your first paragraph, the states that seem to be prone to the largest outbreaks are not the best for chasing, with many more urban areas, hilly/mountainous areas, and tree covered areas. Combine all of those and you get a tornado outbreak that could be extremely dangerous to chase and also has the chance of being very deadly.

I still cringe at the thought of a super type outbreak occuring during the late spring/early summer months, may-june-july. It is unlikely, due to the dynamics often lacking, but if it were to occur, the amount of people outside at sporting events, golf courses, etc. would be so much higher then that of the spring/fall months that you could be looking at a very high death toll.
 
I've sometimes wondered what the convective outlook/SPC discussion text for a super-outbreak type event would sound like. The closest resemblance I've seen is from May 30, 2004:

COMBINATION OF LARGE SCALE ASCENT/DIFFLUENCE AHEAD OF THE TROUGH...AND FRONTAL CIRCULATION SPREADING EAST FROM THE PLAINS WILL BE SUFFICIENT TO OVERCOME WEAK CONVECTIVE INHIBITION AND PROMOTE EXPLOSIVE TSTM DEVELOPMENT ALONG AND AHEAD OF THE FRONT BY AFTERNOON. STRONG DEEP LAYER SHEAR...WITH VECTORS ORIENTED PERPENDICULAR TO THE FRONTAL FORCING...WILL INITIALLY SUPPORT DISCRETE TORNADIC SUPERCELLS.

ADDITIONALLY...GIVEN DEGREE OF LARGE SCALE ASCENT SPREADING AHEAD OF THE COLD FRONT...WEAK CAP...AND STRENGTH OF DEEP SHEAR ACROSS THE WARM SECTOR...FAMILIES OF TORNADIC SUPERCELLS MAY DEVELOP WELL AHEAD OF THE ACTUAL SURFACE FRONT.

THIS ACTIVITY SHOULD TRACK E/NEWD ACROSS NRN AR/ERN MO AND WRN IL THROUGH THE LATE AFTERNOON WITH LONG-TRACK STRONG TORNADOES...

ENVIRONMENTAL CONDITIONS ARE BECOMING EXTREMELY FAVORABLE FOR DAMAGING TORNADOES ACROSS PORTIONS OF THE LOWER MS VALLEY INTO SRN IL.

...LONG TRACK SUPERCELLS HAVE DEVELOPED AND ARE DISPLAYING STRONG TORNADIC SIGNATURES...ESPECIALLY ACROSS AR

THREAT FOR TORNADOES IS EXTREMELY HIGH OVER SRN IND AND CENTRAL AND ERN KY...A FEW TORNADOES COULD BE PARTICULARLY STRONG.

Then, at least half of the CONUS east of the MS river (and some areas to its west) was under a PDS tornado watch.

This event was concentrated over many of the same areas as the Super Outbreak, although a bit further west.

Anybody know of any case studies as to why this event did not pan out quite like this-with a lot of tornadoes but very few of them strong/violent? It was a very dynamic and intense system for late May, with a 989 MB or lower surface low. This may be less dynamic than an early April system, but keep in mind instability would be considerably greater (in late May).
 
From all the case studies I've seen, none that compare to the Super Outbreak! I can take a few outbreaks that compare to each other in a different, smaller, but still significant catagory of outbreaks:

Outbreak Catagories:

Super Outbreak: April 3, 4 1974 (alone by itself)

Huge Outbreaks: Nov 2, 2002/ Nov 21-23, 1992/ May 4, 2003/May 10, 2003/ and others that have currently slipped my mind...

Large Outbreaks (usually most tornadoes are confined to a three-state area): May 3, 1999/April 19,1996/June 8, 1995/May 22,1981/May 22, 2004/ June 24, 2003/ May 29, 2004/ May 8, 2003/ April 26,1991/ May 31, 1985/ April 10, 1979/ etc...

Small Outbreaks (most of the tornadoes confined to an area the size of a state): May 5, 2002/May 7th, 2002/May 12, 2004/ etc...


These are just some catagories I made up to classify outbreaks a little better. I guess May 30, 2004 falls into the "Huge Outbreaks" catagory, but it is insignificant to the other "huge Outbreaks", because there were hardly any strong tornadoes in that outbreak, just a bunch of brief and weak tornadoes. I imagine the "Super Outbreak" of 1974 should have a higher number of tornadoes, because I bet many of the weak/brief tornadoes went uncounted. I would bet that the actual number of tornadoes pushed 160.
 
I would bet that the actual number of tornadoes pushed 160.

I have wondered what the actual tornado counts are for certain years. I believe the numbers were low for back then. However, today I'm skeptical the numbers are higher than they should be. Perfect example of how there were tornadoes reportedly spotted where I was and there wasn't a thing. I do accept that due to the contrast and storm distance you can miss things, but when your chasing and you see one tornado yet 8-11 have been spotted from the same storm, that makes me skeptical.
 
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