2016-03-30 EVENT: KS/OK/TX

[samuel stone]

Yeah If you live in Kansas or Oklahoma I don't know why you wouldn't want to give this a shot.

We have a N-S dryline with plenty of moisture/CAPE in front of it with a shear vector and storm motions quite normal to the boundary and sufficient deep layer shear. So discrete supercells are in play.

We have great LCLs and at least sufficient SRH in the effective layer (which is thick) so tornadoes are definitely in play to a degree

We have plenty of convergence and lift along the dryline so storms are in play..

That right there is enough to get me outa the house on a backyard chase. and honestly eastern Kansas has looked pretty good for several runs now..

We do have some definite uncertainties however, all of which have been covered above. I would throw in the weakness from 850 to 700mb as well (S-shaped hodos at least in KS) So we will see.. but I'm definitely gonna have a go at it.

I really like how the dryline on the 4km NAM appears to have a few separate areas of max convergence along the dryline in KS, with areas of low convergence in between, screams discrete storms. Also the convection allowing 4km NAM has now consistently shown a supercell starting around Wichita and moving up towards Ottawa area over the last few runs for whatever thats worth..

Target: Still Emporia, KS (likely moving SW from there)

 

[Jeff Duda]

Current observations as Ben outlined seem to be leaning more on the bullish side, although I'm a bit leery that the ascent from the incoming sub-tropical jet could lead to a washout tomorrow morning/afternoon and decrease the chances for destabilization. Important to note that with the LLJ initially out of the SSW/SW, there will be a chance for moisture to move north in behind whatever morning stuff is there unless we get a big cold pool.

Agreed. I think the "success" of this day depends primarily on 1) how long clouds hold and 2) development of convection upstream of the warm sector (i.e., across portions of E TX/E OK/AR/LA) during the early afternoon, although the "veeredness" of the flow in this case may be a saving grace of sorts, clearing out the region immediately east of the dryline without also moving the moisture out. Moisture is almost already in place, so it probably won't be a matter of waiting for moisture tomorrow. It'll be how warm it can get.

 

[Andy Berrington]

Looking at current observations over S TX, it further supports the notion of moisture coming in behind the morning convection barring cold pools and destabilizing areas closer to I-35 (assuming that's where the dryline sets up). 70 Td at Laredo and 67 Td at Del Rio suggest moisture has made it quite far inland.

 

[Brian McKibben]

70 Td at Laredo and 67 Td at Del Rio suggest moisture has made it quite far inland.

I don't think moisture will be an issue. I am more worried about low clouds hanging around too long. However, new 00z 4km WRF show cells along I-35 by 00Z thur.

 

[Randy Jennings]

Do you guys think there will be enough low level sheer to make things interesting? I just looked at observations and model runs from 0330 0Z and here are my thoughts:

Like Ben, the 0Z observed soundings get me excited about the thermodynamics of this setup - good moisture along the coast spreading north and great lapse rates out west. I compared the NAM and GFS valid 0330 21Z and the RAP valid 0330 18Z (21Z not in range yet). They all agree that CIN will be low to nonexistent, Td's will be good, and LCL heights will be low in the target area everyone has been talking about. The NAM is slower with the eastward progression of the dryline. All 3 have good CAPE from southern KS to central TX, with the NAM and RAP favoring the Wichita Falls to OKC area for the highest CAPE at 21Z/18Z respectively and the GFS favoring the DFW to southern OK area at 21Z.

Sheer is where it gets interesting to me. If you toggle between the RAP, NAM , and GFS they progressively move the jet streak slightly north. There looks to be good deep layer sheer, although the models disagree on timing and location. NAM seems to favor central OK and KS, GFS southeast KS and eastern OK, and RAP southeast KS and central OK. The low level sheer is what seems lacking to me. The NAM has some in southeastern KS and NE OK at 18Z, but it has all moved east by 21Z.

So I'm going to watch things closely, but for right now it looks like a hail event to me with a pop up tornado or 2 possible (but good luck being on it). The morning soundings may change my mind. I would not be surprised if I ended up leaving work at lunch to head north on 35 towards the Red River to chase, but I also wouldn't be surprised if I stayed at home until it was one county away and then went to a parking garage to spot and report hail size.

 

[samuel stone]

Your right SRH is not great near the dry line but it is a tleast sufficient for a tornado threat by 0z in most areas according the the NAM. especially if a SUP can move slightly deviant to the flow and enhance its local SRH. Note that the 0z NAM has effective layer SRH in excess of 200 m2/s2 in portions of eastern KS. this is certainly sufficient for tornadoes.

In addition storm motions will be quite fast perhaps even 40kts acoording to some right moving bunkers, and motion will be quite normal to the dryline so storms should progress east of the immediate dryline atmosphere relatively quickly

 

[samuel stone]

Interesting SPC DAY 1 mentions bouyancy and moisture as a limiting factor along the dryline north of texas. I was not really thinking that would be a big issue. they must be really buying into the early day convection having a big influence.

 

[Bryan Smith]

Interesting SPC DAY 1 mentions bouyancy and moisture as a limiting factor along the dryline north of texas. I was not really thinking that would be a big issue. they must be really buying into the early day convection having a big influence.

Actually I am pretty bullish about moisture along the southern plains dryline. The part of the outlook describing lower moisture/buoyancy refers to the areas in the central plains [reference the 06z outlook composed by Cohen and (Smith, me)] The 30/12z DRT raob will probably look quite potent from a moisture/lapse rate perspective. The 00z CRP and BRO raobs already look "charged".

Bryan

 

[Randy Jennings]

I was awaken to the sound of my phone beeping early this AM with the latest day 1 SPC outlook and like a kid at Christmas I rushed to open it. Looks like I am eating crow this morning, so it is back to the models to see why my post last night, where I said we didn't have enough low level shear, was so different from this AM's SPC outlook. It looks like my issue was I didn't look at enough data. I focused too much on my target of 4 pm.

Looking at the 0330 06Z runs of the RAP, NAM, and GFS, there does appear t be adequate low level shear for TORs in the arklatx region this afternoon. The only hold up seems to be that the instability lags at little further west during that time period.

We'll see. I'm not sure I would head to that area to chase - perhaps too many trees to make for a good chase.

 

[Ben Holcomb]

As Bryan (correctly) predicted, the DRT sounding this morning shows a very stout EML with a great mixing ratio of 14 with a moisture depth over 1km deep. Even the 12Z OUN sounding shows quite the steep mid level lapse rate, and without significant convection in the area, I'm feeling a bit more confident on today. The trough has seemingly taken a more neutral tilt as it bumps into the ridge to its east, which should bode well for better looking hodographs and holding things a bit further west - Better chase opportunities, hopefully.

 

[Bob Schafer]

I had one foot out the door before sunrise this morning and then pulled the plug when I saw from HRRR and RAP that initiation is progged at, like, 18Z. I'm glad I checked data before leaving.

 

[Royce Sheibal]

NAM, HRRR and RAP are really boosting the chances for Tors and Sig Tors up in SE NE and SW IA. Dewpoints in the area are still <50, but they are advecting in from SC NE where they are nearing 60 already. If we can get some clearing by noon I'd expect those 2k Capes to likely happen. The models also suggest the front may get a bit of negative tilt up near the triple point, which causes them to boost SRH significantly. Dynamics aloft in this area are also primed, in the perfect region of the jet, however DPVA seems to be lacking. (Note: Down south in TX/LA/AK DVPA you may get a solid DPVA boost.)

I don't think the tornado window will be large, as the models start convection at 3pm and clear most of the area by 6 or 7, but there is a pretty solid shot. Sadly the models are quite divergent as to where initiation will occur, I've seen as far west at Hastings and as far east as Neb City. So let's say Target: Lincoln, NE (or where ever is closer to the triple point) moving toward Omaha / SW IA after dark. 12Z NAM really slowed the progression of the low down. It appears to be retrograding / re-positioning for a few hours on the last run.

 

[Tim Paitz]

I'm pretty sure Arkansas, Louisiana and Mississippi should be added to today's event. However, the CAPE there is nonexistent but impressive shear makes up for that. I wouldn't be surprised if they get a strong tor out of that. Dewpoints are in the mid-60s there.

 

[Bob Schafer]

I had one foot out the door before sunrise this morning and then pulled the plug when I saw from HRRR and RAP that initiation is progged at, like, 18Z. I'm glad I checked data before leaving.

I should have specified that this was in reference to a Kansas target.

 

[Andrew Constans]

With the 15z run of the HRRR, I could hop on board with a target around Neb City and pushing NE from there. The 15z run shows initiation taking place between essentially Grand Island and the SE NE side of the MO River, but the SW IA cells appear to be in the best conditions the area has to offer (echoed by the composite parameters) especially considering the convection to the NW dies out as the afternoon progresses/the frontal boundary pushes east. Dew points - 60s. Surface convergence - yes. Lifting mechanism - present. Instability - CAPE forecasted to push 2k at 21z. Helicity and to a greater extent shear are the question marks for me, but both appear to be present in that 15z HRRR run with the weakest link being the 0-1km level shear and the 0-6km pushing 60kts.

Disclaimer - I'm getting back into forecasting after a few years and am relatively new to chasing