2013-05-29 FCST: NE, KS, OK, TX

[Tim Supinie]

I've been thinking about the possibility of chasing on Wednesday, and I was kind of surprised no one had started a thread on this yet. Then I took a look at the latest (28/06Z, granted) GFS and NAM, and now I kind of see why. I'm always wary of veer-back-veer wind profiles with these über-negative-tilt troughs, and this one has some ugly ones. The NAM has some pretty disgusting tropopause-level winds (50 kts out of the SSW) all up and down the dryline by 00Z on the 30th. The GFS is better in that respect in southwest OK, but keeps a pretty big cap in place (probably because it's barely mixed the boundary layer any, which I don't buy).

Also, we have the usual good moisture (65 F+ surface dewpoints), good mid-level lapse rates (8-9 C/km), gigantor CAPE (MLCAPE > 3000 J/kg by 18Z), all that fun stuff. The 06Z NAM's mid-level lapse rates are less good by 30/00Z, but that's because it's already broken out convection in the general area by 21Z, and you see the effects of that. Its 18Z mid-level lapse rates are good.

So as of now, I'd be targeting southwest OK, which is fine with me because that makes it convenient to get back to Norman at the end of the evening.

Can I hope that the ugly wind profiles are a 06Z model run anomaly?

 

[JamesCaruso]

Similarly, I am worried about mid/upper flow being meridional and too parallel to the dryline, particularly in KS. Based on this morning's 12Z NAM, the eastern TX panhandle will have flow that is somewhat more perpendicular to the dryline, so that is my preliminary target region, subject to change between now and then of course.

I am also worried that the trough will result in too much large scale forcing and an early event and/or too many storms all over the place interfering with each other. But that's a separate issue that good targeting is not going to fix...

 

[Brian McKibben]

SPC has gone with a Moderate Risk with a 15% hatched. Last night I was worried about anvil interference with the 300 hPa winds progged to be from the south. Veer-back-veer. We could still see some monsters, but I don't know if they will stay discrete for too long.

The 12z RUC forecast sounding below for Clinton looks a little better with less backing aloft than previous NAM runs showed. It could be interesting. I would want to be on cells early in the game. They should mature quickly.

Just looked a forecast sounding from WRF. It looks much worse for the upper levels.

 

[JamesCaruso]

I am worried about the southerly upper jet as well. The Norman AFD also alludes to this issue. But it is what it is; it's the same over the whole region so no impact on target selection. The 500mb flow, on the other hand, does seem to be at least slightly more perpendicular to the dryline as you move south.

I am targeting the eastern TX PH today, but it is tough picking a position on the dryline from north to south... Will have to just see how the surface observations take shape. Leaving Woodward now and will adjust along the way.

Hoping to redeem ourselves after a serious of missteps, misfortunes and misadventures that have left us empty handed thus far. Flight out of Wichita back home to Philadelphia on Friday.

 

[Mike Johnston]

Looks like James identified the significant concerns yesterday. I continue to think that we may have early initiation today. The RAP short-term model breaks out precip early in and around the outlook area, height falls are moving into the area and CIN is eroding pretty quickly. As a matter of fact, there are cells going up right now around Salina, KS and the RAP shows a pretty broad area of precip from central to eastern Oklahoma. Will be interesting how this early convection will affect developments later in the day. And, the upper flow being so parallel with the dry line is also a legit concern. On the positive side, looks like the low level helicity could be very supportive, LCL's aren't bad either.