Chase Case #9

This day may or may have not had tornadoes. 18z data will be provided tonight, please wait before guessing the date until people have had a chance to adjust their targets with the 18z data:



-Scott Olson.
This morning, Kansas has been worked over by the cool airmass and there are signs of the cold front making it into the northwestern Texas and Oklahoma Panhandles. I don't like that front with its fairly strong northerly winds behind it. I DO like the deeper moisture evident on surface obs in NE TX and AR......wish it'd make its way up here today.

At the risk of getting burned by inaction, I'm sitting tight on the northwest side of OKC with my hot McGriddle breakfast.....and waiting. I can blast north, west or south at a moment's notice. I hope I don't blow it....

Broad low centered west of Enid should continue rooted south-southwestward to west of Abilene as approaching weak short wave coming off the Guadalupe Mountains drives eastward and intensifies dryline currently east of Lubbock/Midland. Ingredients for a few isolated SCs look good where backed low level flow is focused east of the advancing dryline.

12Z target is Seymour, TX.
A dryline extends from the sfc low through western TX, with a cold front arching back behind it and then curving northeast... A warm front extends from the low through northern OK and extends through southern MO. Nice backed sfc flow exists south of the warm front and ahead of the dryline. I have a rather broad area of interest (and will wait before 18z to narrow things down), but from the looks of it now... I'd have to settle between Altus and Lawton, OK (and will probably be headed south later in the day).
Think I'll play the dryline game to start off with this 12Z data. SGF, TOP, and especially OUN soundings show promise, CAPE aoa 1500 J/Kg, good HEL on the OUN sounding - with at least 45 kts and rougly 50 degrees of speed/directional shear 0-6km. Hopefully we can start to burn those inversions off and overcome the CINH for the 18Z data.

Target as of 12Z: Southcentral OK/ SE OK - Durant, OK.
Morning target is Wellington, Kansas.

300 mb jet combined with intense vorticity advection ahead of the 500 mb shortwave will overspread the E Kansas/NE Oklahoma region with strong synoptic scale vertical motion. The surface low should progress eastward along KS-OK border, roughly along the E-W oriented warm front/baroclinic zone. Morning soundings look like OUN is socked in with some high clouds which would limit insolation and prevent significant weakening fo the cap, but the Topeka sounding looks absolutely juicy.
Lots of fog and even some drizzle reported north of the warm front. Appears to be a fall type event, since the air crossing the lower Great Lakes is warming while moistening, so not a climatologically favorable time of year. The 700 mb temps look quite warm from 9-11 C across much of the warm sector - you'd need some serious heating to overcome that, and with all the low cloud cover that is going to be tough. We aren't given any soundings in Texas, which might be a hint, but the prospects along the baroclinic feature across KS look rather suspect from the morning data. The shallow moisture depth combined with rather weak low-level winds suggests sticking where some moisure pooling can occur, so immediately downshear of the weak surface low in nc OK would probably be the feature to watch early. I guess I wouldn't be too excited to get out the door based on the current look of things.

I'm driving to Emporia and waiting till 18z. That looks like one nasty cap and no moisture to the south. If I was smart I'd stay home in eastern NE on this one...but I like to see what happens and more times than not simply ignore nasty caps.
Oh boy - this definitely looks like a fun one - whew ... (plus I'm feeling sick today, so this chase had better start shaping up soon for me to feel like it's going to be worth the trip.)

Also not overly excited about warm temps at 700mb here, but will be watching to see the direction this moves during the day. Cool, cloudy conditions for the most part to the north of the low, with warmer, sunny conditions to the southwest, along with dry air moving up into the Texas Panhandle. Cold temps aloft with 500mb temps at -13.

I'm going to go out on a limb (my favorite thing to do) and call Topeka to Emporia, Kansas for now - but will watch closely as this day progresses for the possibility of the development of mini supercells, in which case I will want to get close and just north of the low, wherever it's ultimately headed.
I will start at El Reno, Oklahoma. However, I don't like the cap and the lack of low level moisture (esp. 900-800mb). Then again I am 0 for 8 with these so... :lol:
I have a pretty broad area of interest that extends from NE TX into southern IL (basically along the warm front). However, areas further northeast in my "area of interest" are at risk of being capped off (or provide at least poor mid level lapse rates) since they are just east of the 850-700MB thermal axis.
Well, I got beat by the new data. Since I'm still sitting in Moore, I guess my best option is to watch what transpires just north and west of OKC. Hopefully the surface winds can back a little bit. Since its so close, I'm staying home clicking the refresh button on the visible satellite every few minutes. If it looks like its about to go I'll head out.
Not a whole lot of time to give a detail explanation, but I'm going to set up on the east side of Kansas City, MO. I don't like the veered flow to the south (in OK and southern KS), and the dewpoint deficits in TX are high (~25F). There appears to be some decent Tds and warm temps in MO, both of which should be contributing to significant CAPE given the lapse rates seen in morning soundings. Surface winds look nice across central/northern MO... Cap may be an issue, but there may be some divergence in the left-exit region of the upper jet that aides the surface parcels with mid-80s temps and 68-71 dewpoints across this area to breach the cap.

So, with nice looking wind profiles, and higher Ts and Tds under cooler 700mb temps (relative to the OK/TX target), I choose to park in the eastern side of Kansas City, MO, with a decent option east, southeast, and south.
Well even before I saw the 18z data I was thinking somewhere along I 35 in Kansas. Now I think Overland park would be my target along the warm front. It appears that the elevated mixed layer was a little to intense further south along the dryline based on the 12 Raobs. High capes, low LCL's and locally enhanced shear due to backed winds along the front make NE Kansas a prime location IMO.
I agree with Jeff's analysis of the situation per the 18Z obs. While hesitant to venture far from my initial area, I'm going to jog a bit NE towards the warmfront and reposition myself in Springfield, MO - options to push into NE kansas, continue my northeastward progression, or dart back down to my 12Z starting location incase some initiation starts south of the sfc Low and ahead of the Dryline - which appears to not have moved much since 12Z.

New target as of 18Z - Springfield, MO.
Just had my first look. Based on 12Z data I'm heading to Arkansas City, KS.
Hmm... Northeast KS and northwest MO is looking kind of interesting. A few stations reporting mid 80's with Td's in the low 70's with ESE winds along the warm front. METAR's also indicating partly sunny skies, so further warming might be possible. That area is right in the vacinity of the SFC low with excellent directional shear and probably some good SFC convergence going on. I did hand modify the TOP sounding, and there is a pretty solid CAPE area - but there appears to be a pretty strong CAP in the lower levels... Since that area is also west of the 850-700MB thermal axis, I would suspect that those temps may have cooled somewhat...

Right now, TOP and EAX look pretty good... But I am torn between that and the possible action near LSX over towards PAH... It almost looks like a meso-low with cyclonically curved wind barbs near the PAH area... And the moisture pooling with Td's in the mid 70's and T's near 85F - pretty tempting. In addition LSX/PAH are likely experiencing the strongest mid and upper level winds...
Waaaal, Seymour is getting swept by the dryline. Not pleased and likely to bust. Pulling stakes and heading up to Wichita Falls, thence ESE on US82 toward Sherman, TX. I haven't given up my theory, and the intensity of the dry punch shows there's something going on upstairs. Maybe I'll get lucky, while everyone else busts up in northern MO :wink: .