2018-06-23 Event: OK

[Ben Holcomb]

The GFS and now the NAM has been showing some decent potential for a unusual late season setup in central and eastern Oklahoma for a couple days now. Complicating factors include overnight and ongoing morning convection, but a small shortwave passing atop what should be a very moist and unstable environment should kick off a decent round of storms.

Questions on storm mode and timing are all still a bit in the air and probably will have to wait until day of, but there's a decent possibility of an outflow boundary to deal with. High surface temps and LCL's to the south along the red river, a strong cap to the SW and some wonky surface flow as depicted by todays 12Z NAM can all throw a wrench in the setup. With that said, seeing a sub 1000mb low in June, especially in the southern plains, is always attention getting. I would not be surprised to see at least one photogenic tube come from this event in Oklahoma.

 

[chrisbray]

Thanks for getting this started. I have been eyeing this for a while as a possible trip, but uncertainty about Sunday make me wonder if this is worth an overnight trip for one day, or if its worth sticking around and making do with Sunday in anticipation of Monday.

While the NAM shows some pretty soundings, I do worry about storm mode since the shear vectors are due east, right along a very narrow E-W warm sector. There are also the 2 inch PWs to worry about making this very messy/HP. Very curious to hear other's thoughts on an event like this.

 

[Adam Lucio]

I see more I don't like than I do like. My concerns would be departing 500mb flow, never a fan when I see that. I also dont like to see those 850s turning SWerly as the LLJ finally ramps up after 0z. Further south where the spreads are worse I worry about getting into subsidence south of the main jet streak In addition the NAM also doesn't fire convection until after 0z and its all north of the boundary/warm front.

However given the time of the year, a morning outflow boundary can negate all of this, and thats what you want to watch for. Cant complain for late June though and when big CAPE is in play anything is possible.

The next two days look more interesting, assuming what happens this day doesn't cut off the critical return flow currently progged. The fact both the GFS and NAM show a similar evolution is worth noting.

 

[Ben Holcomb]

Chris I will echo your sentiments that the shear vectors will give a big question mark on storm mode. Like Adam said, a big outflow boundary can negate it all and a nice E/W boundary would make those shear vectors perfect. Or we could just end up with a raging MCS all day. I'd definitely consider all 3 days if you're traveling and bring that noob below you with you.

 

[Drew Terril]

My thinking hasn't changed a whole lot since I first started looking at things pretty hard yesterday. My big concern is overnight and early/late morning convection along the areas that I ordinarily would expect to target. That said, both the NAM and the 3km are indicating that convection stays far enough north to lay down a boundary roughly parallel to I-40 but set a little south, but without being so far south as to open up the T/Td spread too much. I'm not working Saturday, it's close to home and close enough to the next day's target area that I will definitely be out. As far as I can tell to this point, Saturday will almost certainly be a vis sat/surface obs day where you find the boundary and go there.

 

[Taylor Wright]

Tons of issues I see at first glance. Pwats > 2" and pretty pitiful anvil relative winds will probably lead to HP mode, target area looks to be south of 40 and east of 35 with storms moving ESE into worse terrain, cap filling in after 21z, 850s are almost non-existent until after 00z. Despite all of this, if a nice OFB is laid across Oklahoma would definitely negate a lot of these issues, however models have been pretty bad at dealing with morning MCS this year so I don't think the true tor potential will be clear until Saturday morning. I doubt I ditch the Astros-Royals game for this one.

 

[Tim Supinie]

Outflow boundaries are in dashed black on the satellite image. The southernmost one isn't reflected in surface obs very well, but there seems to be a coherent line of cumulus. The middle one is pretty obvious in the Oklahoma Mesonet data. The northernmost boundary isn't very obvious in surface data, either, but there has been a line of convection trying to develop on it (that convection doesn't look very healthy on the latest image, though).



The morning Albuquerque sounding shows a seasonably warm EML, with the potential temperature in the mixed layer at ~48 C. This will probably require some lift to get over. We'll have some mesoscale lift with the outflow boundaries, but some synoptic scale lift would also be useful. There's a (very) subtle mid-level wave over the TX panhandle that might help, circled in the attached water vapor image.



The HREF members all have some convection developing on the outflow boundary(ies), and quite a few appear to have supercell modes for an hour or two before growing upscale. A not-too-cherrypicked forecast sounding from southern OK looks pretty decent (a three-digit number on the 0-1 km SRH! ) Moisture is probably a bit over-done, though.



The biggest question to me appears to be how long we're going to have discrete modes. The latest HRRR runs are fairly pessimistic on that, so we'll see. The HRRR also has more realistic (i.e. lower) inflow moisture, which would tend to result in stronger cold pools and therefore more rapid upscale growth, so maybe it's onto something. I have a commitment in Purcell, OK from 4-6 pm, so maybe I'll find a storm on my way back to Norman.

I doubt I ditch the Astros-Royals game for this one.

Given the quality of those teams this year, I think we know how that game is going to go.

 

[Drew Terril]

HRRR has been indicating more convection on that northern boundary that has been showing and also hasn't done well with observed moisture return. According to OK mesonet, 70 degree dews are already making it north of the Red River which none of the recent HRRR runs have shown until a few hours later. So I'm taking anything the HRRR says with a rather large grain of salt. Right now (again looking at Mesonet), it appears there's a wind convergence south of I-40, roughly on a line from Chickasha to Clinton. I've been watching this most of the day and it's more or less stabilized as far as movement is concerned. Dew points are considerably higher along and south of that line, with many mesonet stations to the south of it reporting 70 degree or greater Dews. I'm about to leave home and that's the area that I'm going to concentrate on, barring any major shifts in how things are lining up.