Hallam and Greensburg Similarities

[Mike Peregrine]

This has been eluded to, but was curious about getting some thoughts on this from people who may have been on both or at least one of the two? To me this storm seems so similar to Hallam in so many ways. I have been thinking about it ever since. Motion, behavior, general environment with that Theta-e surge ... it all seems so familiar. I'll bet that if anyone could have gotten vidcaps at the time (among the dust storm surrounding the tornado and some better lightning), that Hallam and Greensburg would have had a strikingly similar appearance as well - the fact that both of these beasts completely enveloped a small town in their respective paths is also a horrible similarity.

One thing I noticed in Mike Scantlin's photos (which are exceptional from a structural perspective - and every other perspective), was that the mesocyclone appeared extremely well developed at the time the tornado was nearing Greensburg. There looks like some amazing mid and upper-level rotation going on there. The fact that even the anvil made it into that first shot is just incredible. I just don't think the analysts could have possibly asked for a better photo than that first one Mike posted. From the angle of the shots I'm not sure which way we're looking, but I would guess we're looking from the west/southwest through that incredibly well-defined RFD at the tornado. Inflow appears to be on the lower right of the shot feeding this monster. The tornado looks like it's pretty much smack in the middle of the meso from this angle, but this is because RFD is extended back so far from the tornado itself ... also VERY reminiscent of Hallam. Wondered if anyone else noticed other similarities. One thing is for sure ... they are both historic events.

The tornado itself looks pretty similar to the Feb. 28th monster in Linn Co., Kansas. But there weren't as many environmental similarities with that day, I don't think.

 

[mike scantlin]

the highway in the pictures is 183 N-S. the first picture we were on 183 and i was looking NW. the second picture i was looking due N. the 3rd and 4th are pointed NNE right at Greensburg. i'm going to find a map with the tornado track and use it to plot where i was and where the tornado was when the pictures were taken.

 

[Willie Dines]

Hey Mike P, just reading this has sent a chill right through me, because there have been times over the past few days, that Hallam, NE, has came to mind, when looking up the images, structure, etc of the tornado and the meso and like you say, both the similarities of both Hallam, NE and Greensburg, KS, have both been completely swamped by a beastly monster.

There is another slight oddity as well, as reguards the damage paths... In Hallam, only a small portion of the tornado, had went over the town, as the other 70% of the damage path was to the East of the town, and in Greensburg, there was about 1/5 of the tornadoes path width, that was of to the East of the town there too, but in both cases, I feel that this was simply due to the magnitude of the tornadoes width

I will say though that the RFD may have been increasing the meso and/or tornado's rotational speed and momentum, as I had found using the tornado machine, that when I was using the central fan, (Used to make the tornado) the tornadoes were of moderate strenth/width, but when I added any kind of extra inflow, the tornado naturally increased in strength (Wind speed) and in width and I feel that this may have been a factor also

Those pictures that you have taken Mike S, are incredible, especially the first pic, as Mike P has mentioned

There is one thing that I'm wondering though, was the Hallam, NE '04 supercell, not an HP storm, or was it an LP Supercell also?

Willie

 

[afischer]

The tornado itself looks pretty similar to the Feb. 28th monster in Linn Co., Kansas. But there weren't as many environmental similarities with that day, I don't think.

It's interesting you bring this topic up, because I actually noted a few similarities between the Blue Mound KS event on Feb 28 and the Greensburg KS event on May 4. Each had a rather similar upper air pattern with a longwave trough over the western US and a difluent upper level jet just starting to nose into the target area by 00Z. (The Feb 28 upper air pattern was more progressive, though). I recall that picking out a well-defined shortwave impulse in each case was tough, but in the end there was probably an embedded incoming shortwave trough in each case that helped out with initiation. Also, each supercell initiated 30-60 minutes before darkfall along a slowly retreating dryline, and in an area where moisture advection was maximized (and quite strong). I haven't investigated the events closely though, and the similarities may stop here. (For instance, the Blue Mound storm may have only had 500 j/kg MLCAPE to work with, whereas Greensburg may have had close to 4000 j/kg). There could also be plenty of similarities between the Greensburg storm and Hallam.

 

[Mike Kovalchick]

There is one thing that I'm wondering though, was the Hallam, NE '04 supercell, not an HP storm, or was it an LP Supercell also?

Willie

I was out chasing that particular evening near Hallam. Most of the supercells were very aggressive in wrapping rain around the tornadoes.

http://www.crh.noaa.gov/oax/archive/hallam/hallam.php

The NWS labeled that particular storm..an HP.

 

[Willie Dines]

I was out chasing that particular evening near Hallam. Most of the supercells were very aggressive in wrapping rain around the tornadoes.

http://www.crh.noaa.gov/oax/archive/hallam/hallam.php

The NWS labeled that particular storm..an HP.

Thank you Mike

The reason why I'm asking is because the Greensburg Beast, was produced, by what looked to be an LP supercell, and yet, the Hallam Monster was produced by an HP supercell, and so, I'm now wondering, even more so than before, what was in the exact make up, to make these storms so dang potent and violent?

Willie

 

[Mikey Gribble]

If the Hallam storm was HP, it wasn't until later in the night when it got big (and hit Hallam). Last time I checked, the Hallam tornado was still considered one long-track tornado by the survey team, but in reality the tornado that was deemed long-track was actually two tornadoes. I and many other people have video of the new tornado forming.
The main thing I remember about the Hallam storm was how fast it tornadoed. To this day I have never seen a storm go tornadic that fast. It went from a tower to having a tornado in something like 30 minutes. It was incredible. The Greensburg storm took a while to get going, but my god were the conditions perfect for tornadoes out ahead of the Greensburg storm. The biggest thing that impressed me about the Greensburg storm was the length of time that it was tornadic (something like 8 hours). That is pretty damn incredible too.
The Hallam tornado was a 2.5 mile wide F4. Greensburg was 1.75 mile wide F3 on the old scale(somebody correct me if I'm wrong because I haven't paid much attention to the survey from the tornado, but I think it had peak winds of 205mph). So I don't know much about the similiarities between the storms because I wasn't on the Greenburg tornado, but they were both certainly huge tornadoes. Hallam was stronger and bigger, but it didn't get the same kind of attention since it only killed one person.

 

[Andy Wehrle]

The Hallam tornado was a 2.5 mile wide F4. Greensburg was 1.75 mile wide F3 on the old scale(somebody correct me if I'm wrong because I haven't paid much attention to the survey from the tornado, but I think it had peak winds of 205mph). So I don't know much about the similiarities between the storms because I wasn't on the Greenburg tornado, but they were both certainly huge tornadoes. Hallam was stronger and bigger, but it didn't get the same kind of attention since it only killed one person.

I'm not quite sure this is how it works. I think by using the new scale they are admitting that the wind speed estimates on the old scale were wrong, so an EF5 is not equivalent strength to an F3. An EF5 is as strong as an old F5, but according to the new scale, tornado windspeeds in general are lower than previously thought.

 

[Dan Robinson]

The first word that came to my mind when I first saw the tornado was 'Hallam'.

 

[Mikey Gribble]

I don't know much about the new EF scale either, but I think it just took what we know about modern engineering and construction into consideration and they found that weaker winds can do more damage.
I'm just going off of the 205mph, not just that an old F3 wind speed is now an F5 winds speed. The OKC F5 had winds >315mph. The Greensburg tornado was nothing to sneeze at obviously, but it is nowhere close to an old F5 like the one that hit OKC. We hadn't had an F5 since 1999, and now we are going to have multiple F5's every year. I think it is a little BS that there isn't going to be a distinction made between tornadoes that have 200mph winds and ones that have winds over 300mph. There is a huge difference in reality between the two, but both will now be an EF5. I don't know the exact peak winds for the Hallam tornado either, but I would bet it was stronger and we know it was bigger.

 

[Mike Kovalchick]

If the Hallam storm was HP, it wasn't until later in the night when it got big (and hit Hallam).

I think you are probably right. Looking at one of the radar images..http://www.crh.noaa.gov/oax/archive/hallam/0128-r.jpg

It does looks like a very wet classic sup.

 

[Mikey Gribble]

Yeah, there really wasn't any rain under the updraft on the Hallam tornadoes, at least from my vantage point, but once the tornado got huge I still don't think there was much rain, but all I can remember was how big the tornado was so I was kind of out of it by that point. It was just a wall, I couldn't even see where it ended. The only reason I really knew it was a tornado was because of the sound.

 

[Willie Dines]

I know where you're coming from with this, Michael, as I have often wondered the same thing about the Hallam monster.

I think that the differences between the old and new scales, is that the DOW crew were measuring wind speed in 10 sec bursts, whereas now, they have convertrted the data to measure it in 3 sec bursts, but it is also a case that the scale has been somewhat watered down and more refined, because of the more lighter construction materials used in homes, etc, and lighter materials are easier damaged in weaker wind speeds, and so, it is basically an effort to have a more accurate scale, that matches up with modern day materials and conrstuction methods

There is 1 thing that is easily over looked, in a tornadoes power, and that is by how fast/slow moving it is over land.

Does anyone have footage of the Hallam monster, that can be looked at in detail?... if so, can you please post a link or PM me and I'll give them my e-mail address.

Willie

 

[Gabe Garfield]

FWIW, I chased the Hallam supercell (along with Jeff S.), and I can assure you it was a high-precipitation storm when it hit Hallam. Later on, it transitioned to the wet side of classic, but it was mostly HP after dark.

Gabe

 

[Mikey Gribble]

I'm just going off of what it was during the daylight hours. The Hallam wedge didn't get really big until right at dark (at least dark under the storm). Up until then though there wasn't any rain around the first wedge that crossed the highway and the second white cone that turned into the big brown wedge that went on to hit Hallam. At least where I was just East and Southeast of the tornado I never got a drop of rain on me and there wasn't any wrap around obscuring my view. Once again though, once it got huge right before it hit Hallam, that is a different story.