Chase Case #5

[Dan Cook]

Let's try this again, this time with no squabbling.

12z on the morning of the Chase:

300mb
500mb
700mb
850mb


Soundings
Davenport
Lincoln
Springfield
Omaha

 

[David Draun]

The Chicago surface data looks quite familiar. I say that warm front through central IL should be watched :wink:

 

[Scott Olson]

That davenport sounding troubles me but I think I will go with Mankato, MN. Not a lot of data to make that decision but with the 850hPa low approching. Exit region should be somewhat situated to provide some divergence. Most importantly most of the other areas I looked at have rather unimpressive bulk shear and directional shear. A surface chart would help. Moisture looks pretty sad there but it looks like a pretty good surge to bring PWATS at least to 1 inch and low level winds may back to increase the already good SRH in that area.

On second thought that's to dry for me, think I will go 40 miles north of Springfield, IL.

 

[Jason Toft]

I'll take a stab at it...

Somewhere in SE Nebraska. The frontal system should move that direction and the upper level wind setup looks good for creating the shear needed.

Jason

 

[Mike Peregrine]

This is an excellent case study example. I know the date for sure so I won't post any observations - but I remember this setup quite well and it will make for a terrific discussion.

 

[Chris C Sanner]

I'm going to cross the mighty Mississippi at St. Louis and park somewhere around 40 miles northeast of there and follow the front all day in Illinois. I can't ignore the highly backed winds in Illinois, especially with decent moisture not too far south of my spot at the present time..

 

[David Wolfson]

I'm very unimpressed with the moisture and dynamics along the front through northern MO and IL.

The interesting feature for me is the mesoscale wave over north-central OK. This is kicking off a surface low and significant pressure falls and backed winds there and eastward. There may even be warm front genesis going on through south central MO.

This feature should deepen and move to somewhere north of Springfield, MO, through the afternoon. The Springfield sounding is unspectacular now, but should improve as somewhat drier air from the southwest at mid-levels clears the air and allows surface warming.

I see this as a triple-point play and will target Marshfield, MO, just east of Springfield along I-40. Hopefully the storms will cooperate and not get lost in the Ozarks.

 

[Kurt Silvey]

I see two possible setups with the data we have been given; the first is the obvious one in Central IL with the strongly backed winds along the warm front. But I don’t have confidence that there will be some mechanism to clear out the cloud cover and think this could lead to a grunge fest. The second is the warm front along the NE / KS border. There are southerly to slightly back winds here, which lead me to believe the warm front will move north during the daytime. The lows will continue ewd providing some clearing to the east and se. So, I think I’ll sit at home and wait for the warm front to interact with an outflow boundary moving se from the ongoing thunderstorm in Norfolk.

 

[Dan Cook]

18z Data:

 

[Nick Bender]

Target: NE KS, option to push eastward into MO.
Brief Reason: Decent Moisture, TD upper 50's lower 60's; almost a Larko's Triangle setup. Winds are backing, along with a region of diveragance to the east in MO, upper level winds aren't impressive but nevertheless are between 50-70kts. Omaha sounding doesn't scream Severe, but with some heating and some possible clearing as the low progesses eastward, could better support Supercell formation.

Edit - Ah Dan, wish I would have known you were posting updated information a minute before I made my first predicition =p. I'll let it stand how it is.

 

[Joel Wright]

I would start out in Chanute KS. I don't like the colder air to the north, plus the moisture seems pretty shallow. Much better wind fields to the south also. Assuming the trough doesn't kick to far east I would favor southeas KS...

 

[nickgrillo]

Looks like a warm front event... The very low T/Td spreads indicate a very humid/saturated boundary layer (with the 60F isodrosotherm peaking into central Missouri) along and south of the warm front, with strongly backed surface flow (increasing low-level convergence) across the region. Eastern Missouri, Illinois and Indiana could carry the potential for isolated supercells and tornadoes near the warm front. I'd stick on the warm front through the day, and start off around Peoria, IL (per the 18z obs).

 

[Aric Cylkowski]

I have to agree with the Springfield analysis. Nice amounts of helicity present, decent upper level winds, and a fairly weak amount of CINH to work with will probably yield good results as the day wears on, especially once the mid-level moisture starts to clear out.

Chase Target: Vista, MO with a clear path to the Northeast-ish along SR 82. Any thunderstorms that initiate along the incoming line from Nebraska will be in what I consider very favorable weather as the day progresses.

 

[David Wolfson]

Oops. I'm too far south. The secondary low is locating east of Kansas City. The locus of initiation is becoming apparent on radar in Kansas, bowing into northwest Missouri, but it will be several hours before the environment gets right enough to produce along this axis swinging east-southeastward. I'm relocating about 100 miles NNW to Clinton, MO [ed: about 25 miles north of Vista....]

 

[Glen Romine]

Guess I've been missing out on these - but rather quickly recognized the event. Sigh. It would be helpful if folks would pick older or at least less significant events, or better yet - some bust events. Instead, all are big tornado days, and with that knowledge all you have to do is figure out where. That would have killed 99% of folks on this event. This was a challenging event to forecast, and I spent a fair amount of time trying to figure this one out after-the-fact.

Glen