Chase Case #6 (2010 Version)

[Jesse Risley]

I'll have to post some photos later. I chased this day as well, though I can't say what I saw was extraordinary. I tracked the cell that went north of Canton, MO and entered Hancock County, IL, embedded within the squall line (app. 10 miles south of La Harpe where Dave was virtually stationed). I was able to get some nice structure that had rapid circulation embedded within the area beneath the parent mesocyclone, but as usual, the storm wrapped in rain and then produced a tornado that tracked from about 8 miles south of La Harpe, just north of Lake Argyle (near my house) to near Good Hope, IL (McDonough County), producing F0 - F1 damage.

 

[Jesse Risley]

What Damon said. Given my location, I stood as good a chance of seeing a tornado as I could have hoped for up there in southeast Iowa. But man, what a mess! Looking at those radar images, I'd never have expected so many tornado reports from that area.

I default to warm fronts and triple points east of the Great Plains, but the more discrete storms were well to the south in the area first outlooked by the SPC. This is a case I'm going to reexamine.

I can offer a few thoughts after pouring over so much data in creating this case.

1. No doubt the better CAPE values were confined to the southern part of the setup that day. For example, take a glance at the 21z MLCAPE profile (CINH eroded). Check out these 21z lapse rates, too!
2. The H5 jet core was digging right into the Nothern Ouachita/MO Boothel region at 21z. The cell tracked through Pemiscot County, MO and into TN. This puts that entire region proximal to that 70 kt mid-level core.
3. All of this was coterminous with SSW H85 LLJ flow ~ 40 kts with a notable moisture axis entering that region; note the 21z Theta-E advection crux in that region, too.
4. Surface winds across parts the region were backing quite nicely by 22z. When combined with the other vertical shear profiles, though no rawinsondes exists within that immediate area for 0z, we can assume the hodographs were pretty favorable for the maintenance of tornadic supercells (check out some of the parameters on the 0z LZK sounding).

 

[cdcollura]

Good day all,

OK I remember this day too back in 2006. I did not chase it.

Based on me continuing NE out of Unionville, MO and into / across the IA / MO border, I could have been in reachable position for some of the tornadoes. I assume most being rain wrapped, many after dark - Then we had a major river (the mighty Miss) to contend with!

This was a tough one for all of us.

 

[Adam Lucio]

Well since My target area was around Springfield, IL its safe to assume I got on some sort of severe storm. Can't say for sure I would have or would not have nailed any tornadoes. Really any target was as good as the next on a day like this. What a crazy day it was. Not sure why I didn't chase this day in real life, but then again in 2006 I was just starting to expand my chasing. It wasn't until 14 days after this I had my first chase out of the immediate Cook County area.

 

[Joshua Nall]

Hmmm, no tornadoes until well E of me so the line would have probably run me over without seeing any. Saw some storms.

Should've stayed in Memphis, lol. With the information given though I would have definitely continued on up to St. Louis as I had originally planned that morning and still probably not seen anything.

I don't know that I even had a cellphone in 2006 so stayed pretty local back then. Just thinking here....probably would have stayed further south on this same set up now, I mean in real life, Knowing I would be heading home after the event. So the farmland in extreme SE MO and NE AR would have looked really good just because its closer to home. That and terrain effects my decisions more in the Spring than the best parameters many times, when I can identify them that is.... Thanks for the case, Jesse.

 

[Keith Wilson]

I would have hung out around my old stomping grounds of SE Missouri, W. Kentucky and W. Tennessee to see how things broke, getting east of the Mississippi well ahead of the storms and waiting for them to come to me (hopefully before dark). That big one that ripped through NE Arkansas / Boothill of Missouri before crossing the river into NW TN would have been too tempting to pass up, and I would have been waiting for it around Dyersburg or Ridgley.
I should have been all over the Gibson Co. storm as soon as it crossed the river into Dyer Co., though not sure how visible the tornado would have been.

 

[Chip Redmond]

Would have been very close to the bowing segment that produced the Van Buren County IA tornado. Looks like I would have been able to miraculously stay ahead of the line and maybe see some structure but the tornado would have been completely shrouded in rain. Definitely more difficult than originally thought from the data given. Shows just how much we rely on forecast model data to chase and how sometimes to see a visible tornado, it is the big key in modern day chasing. Going to sit back and relook over this case as I have learned a few things in this one and it is a good example for a quick moving early season system.

Chip

 

[ChristianTerry]

Im glad i choose to target south later on. I knew a line was going to form so originally i targeted southern Illinois. Once I saw the cells on the map I thought it would be better to keep out of the mess. How far apart is each data update in real life, because it took 3 hours to move to Union City from Illinois?

 

[Bob Hartig]

I can offer a few thoughts after pouring over so much data in creating this case.

1. No doubt the better CAPE values were confined to the southern part of the setup that day. For example, take a glance at the 21z MLCAPE profile (CINH eroded). Check out these 21z lapse rates, too!
2. The H5 jet core was digging right into the Nothern Ouachita/MO Boothel region at 21z. The cell tracked through Pemiscot County, MO and into TN. This puts that entire region proximal to that 70 kt mid-level core.
3. All of this was coterminous with SSW H85 LLJ flow ~ 40 kts with a notable moisture axis entering that region; note the 21z Theta-E advection crux in that region, too.
4. Surface winds across parts the region were backing quite nicely by 22z. When combined with the other vertical shear profiles, though no rawinsondes exists within that immediate area for 0z, we can assume the hodographs were pretty favorable for the maintenance of tornadic supercells (check out some of the parameters on the 0z LZK sounding).

Thanks for this analysis, Jesse. Part of it reinforces something I've pondered over the past year or so regarding the importance of southeasterly or southerly surface winds. That's one of the things I instinctively look for, but I think that at times they can prove to be a red herring.

That H5 jet max beelining for the bootheel in the midst of 3,000 MLCAPE would have been a bright red flag had I known about it. But look at the surface winds down there--they're veering out of the south-southwest. Bad news for helicity? Not really, not with nearly straight westerly H5 winds. We're looking at better than 45 degrees of veering with height--certainly enough to get the job done, and it did, as evidenced by that mongo supercell that tracked through AR, the bootheel, and on into TN.

My growing sense of things is that veering surface winds matter a lot more out west, where they're typically linked with dry air advection from the dessert southwest. Near and east of the Mississippi, that concern doesn't seem to be as much of an issue. As long as good deep layer moisture is present, it seems to me that helicity is helicity. Northwest flow outbreaks are a good case in point, but this chase case also seems like a good illustration.

 

[Dave Rennie]

I'm trying to get some sort of handle on svr forecasting, so I thought I would look at this chase scenario in reverse order to kind of "reverse engineer" the observational events leading up to the final outcome.

My problem is, after looking at the first post (which includes all of the data references for each forecasting period leading up to the chase) there are 88 links to maps, satellite and radar images, soundings, etc.!

I believe that if I were to print out each item and try to sort through it to try to locate any patterns, my brain would end up being fried due to information overload! I might be able to absorb and correlate all of that information further down the road after I have gained some experience, but at this point the effort seems daunting, to say the least.

Can anyone offer any list of minimum data sets that would at least get me in the ball park? At this point I'm not looking for the accuracy that would allow me to park and set my camera on the tripod and just wait for the storm to develop, move in and drop a tornado! My intent at this point is to establish the key indicators that would provide the most "bang for the buck" information-wise, that I could absorb without losing sight of the forest for the trees.

Thanks, in advance, for any suggestions!

 

[James Gustina]

I kind of screwed myself over early here. I was pretty reluctant to cross the Mississippi because I didn't know how easy it would have been to double back to Illinois if stuff shot up there. I also had tunnel vision on Illinois here which hurt me more than it helped. Gonna have to keep working at fixing that.

 

[Marcus Diaz]

If anything, I would've gotten those tornadoes in NE MO, but looks like it was a rainy, linear mess with embedded supercells. Tough chase, given the terrain and storm motions. Thanks again Jesse!