tornadotony

Major morning convection on the 00z GFS for both Fri and Sat, and the STJ is still carving across N Mexico into TX. I'm certainly taking model QPF at face value this time and assuming an outcome substantially less than the ceiling suggested by H5, rather than falling for the "holy crap, that trough in mid-May without drought concerns can do no wrong" voodoo I did last week. This is the second trough in a row that looks like a borderline-inevitable outbreak at this time of year, and better than most anything we've seen late season since 2010-2011... but this is no ordinary season.

 

Now, obviously, there will still be some tornadoes (at least Saturday), just as there were every day last week.

Yep.  As long as the STJ is prominent, say bye-bye to prospects of a significant EML and widespread favorable thermodynamic profile.  Gotta hope the first days of these systems are prolific like Wednesday was, or else you know what you're getting afterward.

If you had to put some sort of value of damage or casualty potential with a tornado, that one is almost certainly way up there, considering it's path length, size, intensity, longevity of maintaining said intensity and forward speed. The fact it killed 72 people (and the ratio of fatalities to injuries) without going through a town of more than 1500 people (per the 2010 census) speaks for itself.

Interesting -- I'll check that out, and be on the lookout for any publications from his work. I've driven through the Hackleburg-Harvest damage path where it crossed US-72A near Trinity a few times already. Impressive. (Actually, when I visit my parents in HSV next, my trip will be bookended by that and the Moore/Shawnee paths on I-35/40 -- three incredibly impressive swaths across major highways).

I've seen the track thru Anderson Hills, Old Railroad Bed Rd, US 72, Tanner, Hillsboro, Mt. Hope, Oak Grove, Phil Campbell, and Hackleburg. It's incomprehensible that it was all one tornado. Just unfathomable. It goes on and on and on and on forever seemingly.

I was focused heavily on the HSV-area storms yesterday, since I have family there, and I agree to an extent. It appeared to me that the outflow boundary from the MCS may have been draped across the northern row of counties in AL for several hours during the height of the outbreak. One storm in particular, which initially produced the catastrophic Hackleburg/Phil Campbell tornado, seemed to weaken a bit as it moved northeast from that area. Then, it suddenly went crazy upon reaching the Tennessee River, producing the Limestone Co. wedge near Tanner/Athens with visibly much-lower LCL's than the southern storms. For the rest of the afternoon, supercells trained over this general corridor and would each develop strong low-level rotation as they entered the Dectaur/Huntsville metro area.

On the other hand, it still seems that the most prolific, violent tornado-producers were over the open warm sector, south of any clearly-defined boundaries from early convection. So, while I don't believe the MCS is what "made" this outbreak by any means, it may have at minimum not reduced its overall severity.

A buddy of mine here at UAH is studying this boundary for his M.S. thesis. The Hackleburg tornado was along or just N of that boundary for most of it's life. It was high-end EF3 to EF5 intensity all the way from just SW of Hackleburg to near dissipation in nrn Madison County, an incredible distance of about 85 miles. The Cullman tornado crossed the boundary near the Cullman/Morgan County line, where it grew to 1 mi wide, high-end EF4, and there was a substantial loss of visibility. Both storms dropped tors within an hour of first echo, 50 min in the case of Hackleburg. He had an oral presentation at SLS last year on it that should be available on the conference site.

It wouldn't be the asphalt scouring, the EF3 in Americus, GA on March 1st, 2007 scoured the pavement. I remember seeing something in the survey for the Philadelphia tornado that said that a mobile home was thrown 300+ yards without any sign of a ground impact in between, after which it was obliterated, with the fatalities occurring here as well.

I've gone through this thread multiple times since I joined the site and it is always a worthwhile read.

It was the multiple, large gouges several feet into the ground that led the Philadelphia tornado to being rated EF5.

I have talked with Springfield NWS numerous times and did some walking through the damage path with them. The impression I got from them is that this is a solid EF-5. The winds probably varied a bit with in the tornado. I have walked every stretch of this damage path and I would say that parts of the it were strong EF-4 to low EF-5. Then there are segments of strong EF-5 that probably had winds at 250mph. If you walk every inch of the path you can see the parts that were just a hair stronger. So I believe that 70% of the path was probably 200-210mph winds. But there are segments of probably 225-250mph winds. Also remember this when you talk about St. Johns. This is a huge building that actually got shifted off of its foundation a bit. And St. Johns was on the edge of the tornado and didn't take the strongest winds. Also when it hit Rangeline (Home Depot, Walmart, Acadamy Sports) it was a hair weaker. Probably winds around 200 mph. If you walk that path numerous times you can see the wind varying in spots. I think that is why there is some confusion on this. The bottom line is this is the most deadliest tornado in modern history. You have to go back to the Tri-State tornado for more deaths. That tornado spanded over 200 miles on the ground. The Joplin tornado did all of this in a 6 mile stretch. Also the Tri-State tornado was prior to tornado warnings.

Just curious regarding the shifting of St. John's...was that the whole building, the big tower, or some other part of it? Anyway you slice it it's impressive...just curious. Also, thanks for sharing your story. I can't imagine what that must have been like to cover that.

Low-end EF5 is such a joke. That's like saying "small blue whale" or "poorest billionaire." It's stupid.

Thanks, Tony.

Yeah, I've been wondering about the 250 mph estimate. If I read correctly, they described the speed as "instantaneous" or something like that, which lead me to believe that the 3-sec value (upon which the EF scale is based) would be lower-- right?

I am having a hard time getting my head around the idea of a tornado with winds 25% stronger than Greensburg and Parkersburg. I mean, that doesn't even make sense to me. Like you, I am kind of shocked in the "Enhanced Fujita Ear" to hear a figure like that even mentioned. It looks like it really might be a contender for strongest surveyed tornado. Just wow.

Just bizarre.

My take is that instantaneous is probably being used synonymously with 3-sec gust. It seems bizarre. But to me it makes sense just looking at the death toll. Yeah, it was rain-wrapped, but so was the Moore tornado largely when it was in Moore. Greensburg was at night. Parkersburg was largely rain-wrapped. The Topeka tornado in 1966 wrapped itself in rain as it crossed the city. Rain-wrapping alone cannot possibly explain 142 fatalities.

I see tornadotony lurking. I'd like to hear his opinion-- he's an expert on this topic. Tony?

I doubt the entire area that SGF has painted as EF5 received EF5 damage. It's impossible to say. I didn't think we'd ever have a tornado on the EF-scale where the MIC at the office in whose CWA it hit would estimate a peak wind of 250 MPH. Think about what kind of damage would have to be done for that estimate and think about the EF-scale. Each ranking of the EF-scale goes by roughly 25-35 MPH gradations.

EF0: 65-85 MPH

EF1: 86-110 MPH

EF2: 111-135 MPH

EF3: 136-165 MPH

EF4: 166-200 MPH

EF5: >200 MPH

Essentially, if we still had a "6" rating for a tornado, following that pattern (and even incorporating the fact that the ranges increase as you go up), you'd likely expect this tornado to breach the minimum wind speed for that. Now, how you would describe something as a "6" would be beyond my paygrade. But I'm hoping this puts the level of damage that is being described from SGF into a proper historical perspective. When you legitimately estimate the max winds to be 50 MPH into EF5, you're essentially trying to describe this as being the strongest tornado at least ever surveyed.

I understand why you reach that conclusion-- because it's logical, given that there are 5 colors in the legend and 5 colors on the map. I'm wondering if maybe that inner isotach equals high-end EF4 vs. lower-end EF4-- like a half-grade indicator. I know that might sound ridiculous, but I find it almost impossible to buy the idea of an EF5 damage area being that large, when for every other F5/EF5 historically, the instances were just a house or two or maybe a handful of homes at one end of a subdivision.

No, it's definitely the EF5 indicator. The colors get a bit garbled on the map because of how they overlay.

I'm ok. My family is ok. We just got power and phone service restored. 3 blocks away is completely gone though. I'll post a more detailed account once I check in with everyone.

We know of at least 2 people we know that died. One was protecting his wife and died from injuries. She survived, he didn't. One had a compound fracture and bled to death, they couldn't give her a transfusion because they didn't have her blood type.

It's great to hear from you!

I am no expert but I think tress could go up to EF4 damage. I remember seeing tree damage in Andover,KS, Moore, OK, Harper, KS, and Parkersburg Iowa where not only was the trees completely debarked but also shredded down the center. I dont think there were even stumps even remaining. I am seeing trees in Tuscaloosa that are looking comparable. This tornado was at least an EF4 and no less. It is very obvious how violent this tornado was.

Errr, no, you cannot possibly have "EF4" damage to trees from a tornado. The EF scale doesn't allow it.

3 confirmed dead in Kemper County MS per TWC Breaking Twitter.

Cullman tower cam video will go down as one of the top tornado clips of all time, IMO.

That thing has moments where it looked like Andover and moments where it looked like Xenia. We were watching here at VU and I think all our jaws dropped.

New Albany, MS had a TVS go right through the center of town.

Monster TVS. Absolute monster.

Cell currently WNW of Greenwood, MS is probably our first long-track tornado threat from the new cluster of development. Rotation appears to be tightening quickly. Greenwood sfc ob is at 81/72 right now, and this warm/moist air is surging northward in the wake of prior convection.

What scares me is that those two cells there (the northern one is strengthening) are just south of the big MCS this morning. God only knows what boundaries may be in place there.

00Z SPC WRF is a bit of a mess...here's tomorrow valid 12z

It also says bye-bye AL and TN...

It's these differences that will probably cause them to not pull the trigger on a high until the 2nd outlook at 1300Z if they dont at 0600Z

I would think the southern area (TN, AL, MS) is pretty much a High Risk slamdunk.

Normally I would agree but the capping gradient is much stronger than it is today and the LCL's are, as usual, a little high as you go south. Ironically it will end up being greatest discrete supercell potential south of a Huntsville-Decatur line, but greatest tornado threat north. The narrow area where the two overlap slightly may end up being the "sweet spot" where the full potential of the parameters may be most well tapped.

P.S. the NAM shows a nice cold-pool stabilized region in ctrl TN at 18Z tomorrow...

And then shows rapid destabilization during the afternoon.

I don't have a lot of time to type, but man is this going to be a long 3-4 day stretch. Gotta feel for MEG, LZK, TSA, etc.

Outbreak of the century?

I was thinking more like millennium.

12z gfs

holy moly

Bloodbath.

09z SREF already popping a 50 area in nrn MS at 00z Wed, 87h out...

The 00z GFS is just sick...major severe event from TX to ME Monday-Thursday...unreal...65 dews in Quebec...60-65 in ME and New Brunswick...WTF...