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Chase Case #5

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

12z on the morning of the Chase:

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300mb
500mb
700mb
850mb


Soundings
Davenport
Lincoln
Springfield
Omaha
 
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.
 
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
 
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.
 
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..
 
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.
 
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.
 
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.
 
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...
 
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).
 
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.
 
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....]
 
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
 
I like central Illinois. There is not much instability but I think there is going to more low level cape that will be hard to detect. I like the backing winds along the warmfront also. With great low level shear I feal like this low cape enviroment will be more tornado productive that some might think. Target is peoria, Illinois.
 
I don't like all of the clouds and rain in Illinois, and I usually don't like chasing when a warm front is involved. However, there seems to be a little clearing in southern Illinois and temps have warmed up into the lower 70s. I will watch the warm front and start in Litchfield, Illinois. :?:
 
It would be helpful if folks would pick older or at least less significant events, or better yet - some bust events.

I have a couple that fit the bill that I'm just ITCHING to do ... unknown, long-forgotten, impossible to track events. I can't wait to do them, but will hold off since work is SWAMPING me silly at this point.
 
Based on just the 12Z I'll go with Bethany, MO

If additional data is given I may adjust.
 
I agree with the warm front area. Winds are veered a bit south of the warm front (MO and southwestward). The strong wave on the 700mb plot at 12z across the plains will progress eastward, leaving much of OK and KS in subsidence. Things don't look too terrible down there, and the surface flow is backed a bit (PNC is 70/61 with a slightly-east-of-south wind). There does appear to be plenty of stratus around, however, so I'm not too hot on instability prospects. With decent mid-upper level flow, and with the low-level winds remaining OK, I do think there is a thread down in southeastern KS, eastern OK, and maybe just into southwestern MO. Flow behind the wave (at 700mb) is poor, which, with the likely veer low-level flow, leaving me looking elsewhere.

The clouds and precip along and north of the warm front across northeastern MO and point east and north is disturbing, and certainly not good for the development of strong surface-based instability. Dewpoints are pretty nice, however, immediately along the warm front in IL and IN. In addition, IR shows cloud tops to be relatively warm in central IL, where reflectivities are still pretty high. So, I'd say that the mess over IL is likely weakening... In addition, sfc obs indicate some breaks in the clouds over eastern MO and central IL. The 500mb isn't very good here, however, and lapse rates on 12z soundings are nearly moist-adiabatic (not good). 500mb temps upstream aren't any cooler, so I'm not sure if the lapse rates will steepen much, except perhaps through large-scale upward motion ahead of the trough. So, since I'm looking for tornadoes, I'd either go with the slightly more backed flow near Ponca City, OK, or, more probable, near the warm front, where the 68/65 with SE wind ob in extreme west-central IN is calling my name (or the 66/63 with mostly cldy skies in central IL).
 
So, since I'm looking for tornadoes, I'd either go with the slightly more backed flow near Ponca City, OK, or, more probable, near the warm front, where the 68/65 with SE wind ob in extreme west-central IN is calling my name (or the 66/63 with mostly cldy skies in central IL).

My chase partner and I chased east of PNC this day. It wasn't until later that night when we found out what unfolded elsewhere... It didn't take but 10 seconds to recognize this day from just the H7 map. I'll give a dollar to the first person who can post a chase case that no one recognizes, which will be much more stimulating for the group... like a "one tornado" day, or maybe a bigger event back in the 80s or earlier. Unfortunately, archived data back into the 50s to early-mid 90s isn't exactly readily available for everyone :(
 
I'll give a dollar to the first person who can post a chase case that no one recognizes, which will be much more stimulating for the group... like a "one tornado" day, or maybe a bigger event back in the 80s or earlier.

... Or an event that didn't occur in the Plains. That would REALLY test some forecast skills.

Anyway, I'm not going to participate in this case since I already know the day, and I don't want to spoil it for anyone.
 
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