The Destructive Moore Tornado
- Thread starter John Olexa
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JamesCaruso
Staff member
I thought the front/dryline intersection was further south - which is why I was personally targeting southwestern OK not too far from the Red River. See graphic from SPC MSD issued at around 2:30PM CDT and surface obs from 3:00CDT. Am I interpreting this wrong?
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Joe Karel
EF1
This is how I was interpreting the sfc/radar.
*Hopefully I attached those correctly*
*Really struggling to get them to load right but I think you can see my analysis, Radar image fronts are drawn behind the front so you can see the radar echoes*
*Hopefully I attached those correctly*
*Really struggling to get them to load right but I think you can see my analysis, Radar image fronts are drawn behind the front so you can see the radar echoes*
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joel ewing
EF5
Moore Tornado
That begs this question: Would a status upgrade to PDS have gotten the attention of even one more citizen and made any kind of difference in the outcome?
That begs this question: Would a status upgrade to PDS have gotten the attention of even one more citizen and made any kind of difference in the outcome?
JamesCaruso
Staff member
Hi Joe - your images attached OK but a bit small, and resolution is lost when trying to make them larger. Nonetheless, I can definitely understand placing the triple point where you did. Why do you think it was drawn further south in the MSD? (Not asked as any sort of criticism of SPC, only seeking to learn and understand; maybe based on other meso-data, satellite, etc.??)
I was unable to read the time on your radar image. It shows only two storms; was the northern one the future Moore storm? I remember there being at least three nascent storms just in my target area of southwestern OK, with the northernmost storm being like the fourth up the line... So this is not jiving with what I remember from my chase experience... But regrettably I did not save any of the images I was looking at.
It seems that lots of other chasers were in the same area as me, further south. I have yet to see any discussions on here either before or after the event explaining the choice of one target or another... I hope folks will share their pre- and/or post storm analysis. Can it be that the southwestern quadrant of OK is being thought of as "all one target area" that day? I wouldn't think so, as once committed to the more southern storms the Moore storm seemed far enough away to be out of range, especially with the northward component to its movement, and like I said there were still plenty of chasers near me to the south, including tour groups and the TIV.
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JamesCaruso
Staff member
Another observation is that once the Moore storm dissipated, there was not too much more activity up in that area. Storms kept initiating and propagating from an area closer to the Red River, around Wichita Falls, and training to the E/NE, staying well south of the latitude of OKC. So that, too, leads me to believe that the primary initiation point, which I assume was the front / dryline intersection, was further south...
STexan
EF4
Personally, I don't target any areas that had a potential track taking it into a metro area. If the cell does produce in the populated areas, then there's too much traffic, stopped traffic, can't go forward, backward, sideways ... I will not chase if a metro area is the only option. And it's not like there was a deficiency of spotters and chasers and tv and radio teams to cover any incoming cells.
Rob Gardner
EF0
Does anyone have earlier radar from the storm, I thought I remembered seeing an outflow boundary just north west of OKC prior to initiation, and thinking that if the two connected it was going to be bad news, but that could have been the day before.
John Sickels
EF2
Good question. I do know that when there is a PDS Tornado Watch that some of the local TV mets tend to make a bigger deal out of it than they do with a "regular" Tornado Watch, around here anyway (I live near Kansas City and Topeka)...sometimes "regular" watches in this area get downplayed.
However, everything I've read indicates that the local mets/tv/radio/local NWS down in OKC were on top of the Monday situation hours in advance and has been emphasizing that it was quite dangerous.
I guess this gets back into the sociology of watches and warnings. Pulling the trigger on PDS wording too often would be counter-productive, and I'm not sure anyhow if the general public pays attention to it.
Logan Karsten
Here's something I observed. We left Norman at around noon if my memory serves me correctly, which is around the time that OUN sounding was launched. At the gas station in Norman, the winds were out of the South-Southwest. However, it appears that the surface winds quickly backed between 17Z and the time of the tornado, which means those helicity values with the Norman sounding probably increased in magnitude quickly leading up to the tornado. You combine that with the copious CAPE, and you have a monster tornado.
Another interesting observation. The morning HRRR runs showed convection blowing up at 17Z, which it was an hour or two before initiation actually occurred. It would seem like the storms holding off just a couple hours allowed the atmosphere to heat up just enough, and the winds to back just enough to create a volatile atmosphere for tornadoes. Why the southern storms did not exhibit similar behavior, I do not know.
Just my two cents.
Another interesting observation. The morning HRRR runs showed convection blowing up at 17Z, which it was an hour or two before initiation actually occurred. It would seem like the storms holding off just a couple hours allowed the atmosphere to heat up just enough, and the winds to back just enough to create a volatile atmosphere for tornadoes. Why the southern storms did not exhibit similar behavior, I do not know.
Just my two cents.
JamesCaruso
Staff member
Logan, interesting observations. As to why the southern storms did not exhibit similar behavior, note the graphic in SPC MSD # 726, link below, which displays higher bulk shear to the north.
http://www.spc.noaa.gov/products/md/md0726.html
chrisbray
EF4
taken from a reuters article today
"The schools did not have safe rooms, which can cost $600,000 to $1 million to build, but did have a well-rehearsed plan, officials said.
State emergency officials said that they had provided funding for about 100 safe rooms at schools but Moore had not applied for funding for the two affected schools."
"The schools did not have safe rooms, which can cost $600,000 to $1 million to build, but did have a well-rehearsed plan, officials said.
State emergency officials said that they had provided funding for about 100 safe rooms at schools but Moore had not applied for funding for the two affected schools."
Shawn Schuman
EF3
- Joined
- Mar 3, 2012
- Messages
- 273
I noticed the same thing. There appeared to have been several boundaries, actually.
Here are some more thoughts I've remembered since my last post.
I also was initially somewhat critical of SPC forecasters for only issuing a 40/20 tornado watch. I thought there was more significant potential for a strong tornado. It seems to me that there is a fuzzy threshold of around 3000 J/kg of SBCAPE that, once exceeded, seems to make significant tornadoes much more likely (assuming there is some nominal amount of shear to keep storms from becoming outflow dominant). With 5000 CAPE and 150 m2/s2 effective helicity, there was more than enough energy and vorticity to generate a significant tornado. However, with a slowly moving cold front in the region, and with initial storms flying more north than east, I figured they would cross over the front and get undercut by cooler air. Also, the 17Z OUN sounding showed a weird kink in the 1-2 km layer, which threw off the horizontal vorticity vector. Knowing that, a forecaster may have thought storms would have screwy mesos and may struggle to produce strong tornadoes. Perhaps that kink was smoothed out later, though...or perhaps it didn't even matter. I also almost wonder if the Canadian River valley played a role in topographical generation of horizontal vorticity. While there isn't a huge change in terrain around there, there are some hills in the vicinity. The front may have also slowed and stopped. The initial hook formed just a few miles east/southeast of the front, so perhaps there was some additional vorticity there, too.
These thoughts do not explain why the initial storm I targeted (near Lindsay) died inexplicably, and does not explain why the storm to the south (which did produce a tornado or two) became outflow dominant upon merging with a storm to its south. There were a few small showers/storms that merged with the Moore storm as it was producing that didn't seem to impact the tornado or the storm that much, but such mergers seemed fatal to the storms to the south. Given surface winds were more backed east of the dryline in S OK and that the storms moved well off ahead of the dryline in S OK, I am somewhat perplexed by this behavior. There were probably differences on scales smaller than that which the OK Mesonet could resolve that explain this behavior.
I also was initially somewhat critical of SPC forecasters for only issuing a 40/20 tornado watch. I thought there was more significant potential for a strong tornado. It seems to me that there is a fuzzy threshold of around 3000 J/kg of SBCAPE that, once exceeded, seems to make significant tornadoes much more likely (assuming there is some nominal amount of shear to keep storms from becoming outflow dominant). With 5000 CAPE and 150 m2/s2 effective helicity, there was more than enough energy and vorticity to generate a significant tornado. However, with a slowly moving cold front in the region, and with initial storms flying more north than east, I figured they would cross over the front and get undercut by cooler air. Also, the 17Z OUN sounding showed a weird kink in the 1-2 km layer, which threw off the horizontal vorticity vector. Knowing that, a forecaster may have thought storms would have screwy mesos and may struggle to produce strong tornadoes. Perhaps that kink was smoothed out later, though...or perhaps it didn't even matter. I also almost wonder if the Canadian River valley played a role in topographical generation of horizontal vorticity. While there isn't a huge change in terrain around there, there are some hills in the vicinity. The front may have also slowed and stopped. The initial hook formed just a few miles east/southeast of the front, so perhaps there was some additional vorticity there, too.
These thoughts do not explain why the initial storm I targeted (near Lindsay) died inexplicably, and does not explain why the storm to the south (which did produce a tornado or two) became outflow dominant upon merging with a storm to its south. There were a few small showers/storms that merged with the Moore storm as it was producing that didn't seem to impact the tornado or the storm that much, but such mergers seemed fatal to the storms to the south. Given surface winds were more backed east of the dryline in S OK and that the storms moved well off ahead of the dryline in S OK, I am somewhat perplexed by this behavior. There were probably differences on scales smaller than that which the OK Mesonet could resolve that explain this behavior.
You should look at earlier images. Here is the 1859Z scan at 0.5 deg.:
You can clearly see the dryline/cold front intersection in northwest Grady County. The cold front appeared to have two pushes in arc shapes, with the kink between them right along the Canadian/Oklahoma County line. This southern bulge was surging a bit. The beginning of the Moore storm can be seen as the northern most blob of about 30 dBZ reflectivity in Grady County. That blob was dissipating before the blob immediately to its south interacted with it, after which rapid intensification began. The southern blob was flying NNE, so I figured it would overtake the other one and cross the front and no longer be a threat. Instead, the northern blob, which had been moving more NE, remained and slowed down just east of where the surging front was. The front then seemed to slow down as it interacted with outflow from all of the storms forming in Oklahoma and Grady Counties. So the front never made it to the storm. The Moore storm left a boundary in its wake, which can be seen in your image running between Pocasset, Tuttle, and Bridge Creek. There was a second hook-like feature immediately to the north of the hook representing the Moore tornado, and I do wonder if that played a role in the rapid development and intensification of the Moore tornado.
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