Chase Case #4

[Mark Farnik]

Lol I remember this day pretty well, as it was the second to last week of 7th grade in Fort Morgan, and I ditched class in the afternoon to go storm spotting -watched the initial cells go up from the west edge of town around 3 p.m. and then walked back to the middle school and hung out in my mom's classroom, watching the radar until she got off work around 4 p.m., and then we headed back home, which is 22 miles north of Fort Morgan. I remember we drove through some dime to nickel size hail, but that's about it.

The tornado report southwest of Fort Morgan was indeed valid, however - one of my friend's had an uncle whose farm received some damage to some trees, fences and outbuilding roofs on his property 2 miles southwest of town, where the tornado report was logged. I had my mom drive me out there a couple days later and sure enough, the damage was consistent with high end F0 - low end F1 damage. Forgot to bring my camera along, though, so I have no record to back my story up >.<

 

[Brian Stertz]

Thanks for work into this chase case Scott. Sometimes events can be good honest surprises. This one appeared to be one of those days...maybe not for strong tornadoes but quantity for real.

 

[Mike Peregrine]

This is one of those times it would have been good to have access to forecast soundings and additional model guidance, I think ... instability and moisture were certainly in place, but if we could have seen the way the wind was forecast to start turning once the shortwave came over the midwest, it may have been an easier call. Still great that so many got it just based on available data -

 

[Chad Cowan]

This is one of those times it would have been good to have access to forecast soundings and additional model guidance, I think ... instability and moisture were certainly in place, but if we could have seen the way the wind was forecast to start turning once the shortwave came over the midwest, it may have been an easier call. Still great that so many got it just based on available data -

Mike- the 12z DVN sounding showed solid turning with height from the southerly low-level winds to the NWrly mid-levels. Like I said in my first post, that's a big reason I picked that area:

I'm sitting with Adam Lucio in his new chasemobile in Peru, IL. The thing that really narrowed down my target area is the Davenport, IA sounding which shows the best wind profile of all the soundings. I can't for the life of me figure out why the LL winds are southerly in this area but I think it may have something to do with the secondary low over SErn KS. Regarding storm mode, I believe there may be an isolated supercell and tornado threat in a brief window after initiation and transition to a widespread wind event.
...
I actually think today has solid potential for supercells and tors near the Galesburg, IL area. That's where I would have shifted to from Peru, IL. I really like the 77/63 reading just to the west of me with, and with a nearly southerly wind at the surface and NW flow aloft, vertical shear is quite good, especially for any storm that deviates to the right. Keeping a close eye on the CU field forming along the prefrontal confluence zone in east IA...

 

[Scott Weberpal]

The forecast models for this day were essentially useless until about 18z. From the 0100z outlook through the 12z, and 1630z outlooks SPC was all over the place as far as location, storm mode, etc. It wasn't until the 18z RUC and later surface obs that it was obvious surface winds would remain backed enough over Illinois and moisture would make it far enough north for good tornado chances. Even with that, by looking at the pictures one could surmise that moisture was just deep enough for tornadoes, as every tornado that day had a condensation funnel extending no more than halfway to the ground with a debris cloud at the surface.

I remember looking at the 15z RUC at work that day and decided I probably wouldn't chase due to the lacking moisture in N. IL. I got off work at 2:30, stopped at a dealership to look at a car, and finally got home around 4. It was only then I looked at the 18z RUC and sfc obs and decided I would chase. Left home about 4:45 and by 5:45ish I was on a tornado 45 minutes from home - doesn't get much easier than that I was home by 8 pm! Gotta love leaving for a chase, seeing a tornado, sending video to the nextworks and being home all in 3.5 hours.

 

[Doug Mitchell]

Swing and a miss. Oh well, only about a 2 hour drive back home.

 

[Paul Austin]

Latecomer to this one...

(I’m late to this game, so I’ll just read the updates and post as I can as if I had done it with everyone else as an exercise.)

12z:

Since I’m located in FL and I’m not especially keen on NW flow storms, I’ll be sitting this one out. However, my Danish chase partners just happen to be in the states at present, so I will be nowcasting for Kai-Asle, Thomas, and Per. Good luck, guys! Unfortunately, for some reason my computer is only allowing me to acquire data every few hours.

First, I’m going to eliminate the dry line setup in OK/TX due to mid-level temps that are higher than I am comfortable with. The cap will be too strong and forcing too weak in this area.

I really like the southern warm front/cold front intersection area. As the cold front advances and the nose of the jet streak moves southward, the area from near Springfield, MO to near Hannibal, IL looks to possibly be in play for rotating storms, depending on the exact frontal movement and available daytime heating behind the existing precip. Central to southern MO looks nice for directional shear and extra lift due to approaching front and position relative to the jet streak’s exit region. There also appears to be some localized convergence ahead of the front.

Wisconsin presents an interesting target as well, but limited moisture, weaker backing winds at the surface, and the position of the jet streak discourage me from this target. If the low pressure center occludes, which appears quite possible with the strong upper jet streak, winds could become more veered at the surface, which would be less favorable for rotation. Honestly, I’m quite unfamiliar with the Wisconsin area as well, and I’m not thrilled by the prospect of running out of real estate. But I could see some potential here.

Iowa and Illinois appear to offer a little less lift and more unidirectional wind fields. I would think storms in this area would be a little more linear in nature.

Upon conferring with my Danish counterparts, we will begin by positioning near Columbia, MO. This will give us decent positioning for adjustments as updates are received. Incidentally, Columbia happens to be where we all first met in 2006, so nostalgia plays a part in this decision as well. Hopefully, substantial heating will occur with the clearing behind the morning precip. I think there is some potential for tornadoes, perhaps brief one, but the main threats for the day appear to be strong straight-line winds and some widespread severe hail.

 

[Paul Austin]

OK, after reading the 13z SPC day 1 outlook, the system appears to be moving SE at a faster clip than I initially figured. That takes Wisconsin mostly out of play, so I’m glad I stuck with MO. I’m telling the Danish team to stay put for now.

 

[Marc Austin]

(I’m late to this game, so I’ll just read the updates and post as I can as if I had done it with everyone else as an exercise.)

12z:

Since I’m located in FL and I’m not especially keen on NW flow storms, I’ll be sitting this one out. However, my Danish chase partners just happen to be in the states at present, so I will be nowcasting for Kai-Asle, Thomas, and Per. Good luck, guys! Unfortunately, for some reason my computer is only allowing me to acquire data every few hours.

First, I’m going to eliminate the dry line setup in OK/TX due to mid-level temps that are higher than I am comfortable with. The cap will be too strong and forcing too weak in this area.

I really like the southern warm front/cold front intersection area. As the cold front advances and the nose of the jet streak moves southward, the area from near Springfield, MO to near Hannibal, IL looks to possibly be in play for rotating storms, depending on the exact frontal movement and available daytime heating behind the existing precip. Central to southern MO looks nice for directional shear and extra lift due to approaching front and position relative to the jet streak’s exit region. There also appears to be some localized convergence ahead of the front.

Wisconsin presents an interesting target as well, but limited moisture, weaker backing winds at the surface, and the position of the jet streak discourage me from this target. If the low pressure center occludes, which appears quite possible with the strong upper jet streak, winds could become more veered at the surface, which would be less favorable for rotation. Honestly, I’m quite unfamiliar with the Wisconsin area as well, and I’m not thrilled by the prospect of running out of real estate. But I could see some potential here.

Iowa and Illinois appear to offer a little less lift and more unidirectional wind fields. I would think storms in this area would be a little more linear in nature.

Upon conferring with my Danish counterparts, we will begin by positioning near Columbia, MO. This will give us decent positioning for adjustments as updates are received. Incidentally, Columbia happens to be where we all first met in 2006, so nostalgia plays a part in this decision as well. Hopefully, substantial heating will occur with the clearing behind the morning precip.

Hey Paul! I'm at Patrick Martin's house in Thornton, CO! I apparently decided to head for Colorado seeing as it's much closer to FL than your target! I won't give anything away. Let me know when you plan on hopping in your time machine and joining us in the present for some steaks, burgers (for Verne) and beers! Maybe you can hit up ShowMe's while you're in Columbia, MO! Good luck!

 

[Paul Austin]

18z:

From satellite, I appear to have been wrong about the eastward progression of the deep low. A nice line of cu indicates some convection from W central WI down to NE IA, but my Danish team is 200+ miles away. With largely unidirectional winds with height over my initial target area, storm mode, if they develop will likely be linear in nature.

Based on surface wind direction and speed (lighter southwesterlies), I am moving the Danish chasers north toward SE IA. The surface winds are stronger and veer with time in this area. Shear, both directional and speed are enhanced with the strong surface winds. The cold front/warm front intersection should marginally enhance surface convergence. This area is also closer to the nose of the upper level jet max.

We’re hoping for a “Tale End Charlie†along the line of convection evident on the 1815z sat image. So I instruct my team to move NE toward Hannibal, MO. Here, we would have a viable river crossing for any storms developing this far south, as well as options to go N, W, SW, and E.

Upon reaching Hannibal, a small blip on the 2045z sat image in central MO (SW of our initial) catches my eye. Decisions, decisions… It’s not a very impressive blip, but…
Nothing that is within reach really stands out, so I’ve instructed the Danish chasers to wait in Hannibal under blue skies for further info.

Note: all this “I instruct the team to…†is really more of a discussion and consensus. But when we bust, they will all blame me for dictating the whole day. Our friendship will be forever lost. How could you guys make me the scapegoat, after all we’ve been through together?

 

[Paul Austin]

0z:

While my team sat at Hannibal, MO for the last 2 hours, almost any chance to catch the southern tail of the line of cells in N IL vanished. We should have continued ENE, and I should have noticed the field of agitated cu in N IL on the 2045z sat image ahead of the advancing convective line. That would have been promising enough for a decision to continue NE travel. Now the team races east toward Springfield for any storm that might still have a chance to develop prior to sunset (still about 2 hours left, and the SPC Convective Outlook called for storms into the night. We’ll take a chance at some redemption (I really don’t want my Danish friends to disown me), at least some large hail (temps aloft are cool NE of here).

And then the reports…

 

[Paul Austin]

Reports:

I was definitely right to move my team toward Illinois. I was definitely wrong to make them wait in Hannibal, MO, while nice cells were within driving distance. But seeing the towers and hearing the warnings go up, I’m pretty sure my wise Danish partners ignored my instructions. Even had they stayed until 0z, tornadoes occurred within travel time distance (but only with the pedal to the metal). The last report occurred at 206 in Clinton, IL, 2.5 hours away from Hannibal by GoogleMaps estimation. Perhaps they could have made it, but it would have been a frustrating day, to have been on the right track and missed most of the action. Alas, my Danish counterparts decided not to disown me…this time.

 

[Paul Austin]

Thanks, Scott, for setting this all up. This was a great exercise. I was wrong about a number of things. Storm mode certainly played out differently than I expected. Congrats to all who participated in the learning experience, whether you scored or not.

Marc, I don't think I'll be joining you tonight. All flights out of Springfield and Chicago are delayed due to "inclement weather." Oh wait, I'm not in Illinois, I'm still in Gainesville. Sure, I'll just hop in my time machine transporter thing-a-majiggy and see you in a few. Too bad the Danish team is stuck in the midwest. Save me a steak, or at least a burger! Oh, and congrats on the score!