Chase Case #4

[Scott Weberpal]

I have added the SPC 13z Day 1 as chasers would likely have access to it if they have access to the other data included. This should help people develop an initial target while narrowing it down when the 18-20z data is revealed.

I have also added a Wayfaring map with everyone's initial target. http://www.wayfaring.com/maps/show/54091

 

[Andrea Griffa]

After Ft.Dodge tornadoes, I'm at motel 8 in Des Moines,Ia waiting for the morning models.

 

[Michael O'Keeffe]

I'm also going to go for it and target Peoria because just like Brian said this appears to be one of those July Illinois tornado events.

 

[Shane Adams]

I'll start in Chanute, KS. Not really liking what I see, but despite NW flow aloft, I'll gamble those strong surface winds and 850s will pull that WF north during the day before initiation. I'll be pointing south and ready to cruise back towards NE Oklahoma if need be.

EDIT: After reading everyone else's replies, it's obvious once again I have no clue what I'm doing. I'll go ahead and wager this is yet another day I didn't chase in reality.

 

[Michael P. Morris]

Operating under the assumption that I was still based in Norman, I would probably sit this one out as I think the threat is a little too marginal to chance a 7+ hour drive to NE Colorado.

However, for a virtual chase the area near the IL/WI border looks pretty good to me. I worry a little bit about just how much the boundary layer got worked over by the morning convection, but the upper level support is certainly there, and depending on how that 850mb trough axis behaves, the shear profile could improve throughout the day. If I had to pick a starting point, I would choose Rockford, Illinois.

 

[Scott Weberpal]

I see a lot of people are just throwing out targets missing some of the main questions I was looking to be answered in my original post...

"It is up to you to determine whether or not there will actually be chaseable storms (there will be storms somewhere), their severity, storm mode, whether or not you believe there will be tornadoes or if it's a non-tornado event. Large hail? Straight line winds?"

It's easy to just throw out a target, but putting some thought into what type of potential chase day it might be takes a little bit of work.

 

[Patrick Martin]

Starting point: Thornton CO

Scott - thanks in advance for putting this together.

I'm sticking close to home for this one. Looking at the surface plots across CO/KS, would guess this is an early summer (June/July) type of setup. It's only 6am MDT, and dews are already in the low 50's across northeast CO, temps approaching 70 already, and skies are clear. With NW flow aloft across CO, and upslope flow developing closer to the surface, dews may move into the low/mid 50's and not mix out to much. Would hedge as well that temps don't move much out of the low 80's, so the likelihood of tornadoes is very low given some moderate base heights, however some very nicely structured hailers are likely the storm mode of the day, maybe a landspout, but who knows. I'll stay put at my house in Thornton CO and monitor things through the morning. I'll be looking for initiation perhaps across the Cheyenne Ridge area by early/mid afternoon, but at this point, no need to be in a hurry for anything except my first cup of coffee.

 

[AndyGabrielson]

Realistically where I would probably be setting up in Lamar,MO... in hopes that area will be prime for the "tail end charlie" storm if you will. That probably would be the sole hope for a tornado, otherwise I'm afraid IA-KS and points eastward are going to see mainly damage winds and heavy rain fall.
If I was close and I wanted to play the isolated tornado card I think I would be sitting in Blackfoot, ID. I would look for several small/isolated storms/mini bows with some cells not going outflow dominant immediately, it just depends if you can be on top of one before that happens.

Added: Thanks for doing this!

 

[Andrea Griffa]

I see a lot of people are just throwing out targets missing some of the main questions I was looking to be answered in my original post...

"It is up to you to determine whether or not there will actually be chaseable storms (there will be storms somewhere), their severity, storm mode, whether or not you believe there will be tornadoes or if it's a non-tornado event. Large hail? Straight line winds?"

It's easy to just throw out a target, but putting some thought into what type of potential chase day it might be takes a little bit of work.

Scott, as far as me, I will tell you with the next run of the models. I don't choose a definitive target with all explanations of the case only by 12Z analysis, without a forecast map. That's the reason why I wrote only the city where I was.
I'm in Des Moines,Ia. I think I'm not so distant from an hypotethical play.

 

[Mike Peregrine]

Looks like a fairly complicated forecast, and I'm not overly confident at this time. Temp/TD spread is good for the most part, with plenty of moisture available in the plains. Storms moved through last night, no doubt leaving some attendant OFBs. Confidence looks pretty low for tors throughout much of the central plains/midwest. NW flow aloft, with dynamic upper winds means the storms that may initiate along the CF will be moving to the SE rather quickly, making chasing difficult. Plus, not seeing a lot of good backed winds. My guess is that the mode throughout most of the central plains/midwest will tend to prefer linear and bows, moving rapidly. Destructive outflow, but not very conducive to tornadoes at this point.

The best shot in my mind appears to be the upslope stuff in the high plains, where supercells will probably develop at max heating. Even there, not confident in tors. I think the preference will be for large hail and possibly some good structure. I'm going to drive to Sterling, Colorado today and take pictures of prairie dogs, hoping something special happens this evening.

 

[Niccolò Ubalducci]

Scott, as far as me, I will tell you with the next run of the models. I don't choose a definitive target with all explanations of the case only by 12Z analysis, without a forecast map. That's the reason why I wrote only the city where I was.
I'm in Des Moines,Ia. I think I'm not so distant from an hypotethical play.

Andrea I'm moving from Joplin - Missouri to Saint Louis on the I44.

What do you think...

 

[Scott Weberpal]

Scott, as far as me, I will tell you with the next run of the models. I don't choose a definitive target with all explanations of the case only by 12Z analysis, without a forecast map. That's the reason why I wrote only the city where I was.
I'm in Des Moines,Ia. I think I'm not so distant from an hypotethical play.

No problem Andrea, I just like people to give some reasoning when they finally do pick a target. It helps any new folks understand why a particular target was picked and why they think the setup with lead to a certain mode of severe weather. I see these cases as serving two purposes, to help continue to sharpen forecasting skills of seasoned chasers, and help new chasers understand what is happening, why it's happening and what to look for while forecasting a severe weather event.

 

[Bob Hartig]

This, for me, is why these chase cases are so valuable--all the input from different chasers. So many are skeptical about NW flow. Till now, I never was aware of that as a major concern. As long as the lower levels behave themselves, with decent helicities present, adequate moisture moving in, and veering with height, I've figured the potential for tornadoes is there. The Davenport hodograph isn't as curvy as Springfield, but it doesn't seem bad and I think it will improve as 700 mb winds strenthen. My challenge has been estimating where the peak upper level winds will be by around 21z. That's largely guesswork for me, and based on the SPC report, I may have underestimated. So I'm readjusting back to Davenport; I think the jet max is critical for my area, but I don't want to meet it too early in the game. Adam just might be sitting pretty there in Peru, but I'm not ready to bump farther east yet till I see the next runs.

As for chaseableness--Iowa is easy to maneuver in, and the road grids in Illinois are fantastic. Chaseworthiness is another story, and I'm guessing that's what Scott meant. I just don't get my hopes too high with cold fronts in the Great Lakes. If the low over KS lifts through MO, I'm probably in a position to catch the WF; the WF to my north is in unchaseable territory; but where I'm sitting puts me in the region of the strongest jet, and I can sit still or adjust east or south depending on how things evolve.

 

[Sam Kennedy]

I would want to be on the central ND/SD border, because both states look like good targets. There is some directional shear and speed shear. There isn't too much moisture but that might change I will have to find out with the next update.

 

[Scott Weberpal]

Updated Wayfaring map for early morning targets

http://www.wayfaring.com/maps/show/54091