2019-05-18 EVENT: TX/OK/KS/IA

[Dan Robinson]

Still quite a bit of model spread on this day, not to mention the potential caveats that overnight convective evolution from the 17th's event will introduce. The 18z NAM has the least favorable solution so far, with the wave ejecting early and a moisture-scouring MCS plowing across Oklahoma. Euro and GFS have better wave timing, keeping the dryline-adjacent warm sector intact in central/eastern OK/KS and north Texas until afternoon storm time. Wind/thermo profiles are far from pristine with some veer-back apparent and the cap weakening fairly early (21z). Storm mode might be this day's big problem. Any outflow boundaries from Friday will locally enhance potential.

A secondary target may exist in Iowa/Minnesota near the surface low/warm front, though upper support is shown weakening throughout the afternoon up there.

 

[Quincy Vagell]

It's a bit early to speculate targets due to complex convective evolution, but at this stage, I would argue that the area with the highest probability of seeing semi-discrete/discrete storm activity would be around central Texas, on the southern flank of an ongoing/weakening MCS, if such a system does evolve. The multi-model average, including the SREF mean, shows lower 70s dew-points up to around the Waco area. Wind fields look favorable and assuming any MCS isn't overly extensive, there should be more than sufficient instability as well.

The other question mark in this scenario is how far west/northwest does the target extend into? Does a boundary sag into eastern portions of Edwards Plateau? Is there some atmospheric recovery into Northwest Texas? As one goes farther west, more issues arise with wind fields. As you go north, confidence lowers, as convective overturning, particularly from the Red River area and points north, is a real concern.

Of course, severe storms are possible, if not probable, from the DFW metroplex, northeastward across eastern Oklahoma and the Ozarks. Trends would suggest that this threat is largely associated with an MCS. Farther north from there, a secondary target may develop around the Iowa vicinity, but an MCS to the south may limit the northward advection/recovery of boundary layer moisture.

 

[Brian McKibben]

00z WRF runs and 3-km NAM show that we should see airmass recovery for Sat. Some have a narrow corridor of instability developing while others like the NSSL WRF and 3-km NAM are a bit more robust. They all show convection firing. 00z 3km NAM brings hope as the hodographs look decent. For a day that seemed dead this is positive news. However, we still need to see what happens with the early morning convection. Don't write Saturday off just yet.

 

[Quincy Vagell]

Well, 12z model solutions, for the most part, show less deleterious effects from convection early tomorrow across Oklahoma and southern Kansas.

In the wake of early day convection, the model consensus places a <1000mb low in northwestern Oklahoma between 21-00z. Ahead of the low, models show a warm sector that’s not razor thin, but also not super huge, but large enough to catch your attention.

The low-level jet looks less veered than earlier model solutions showed, surface winds remain backed and quality boundary layer moisture recovers. I would keep a close eye on dew-point trends, as even the HRRR pushes 70F dews up toward the dryline in south-central Oklahoma between 22-00z. It would be one thing if just the NAM was showing that.

Stay tuned, but if there’s a silver lining about a scenario with less convection late tonight in the northwestern Texas vicinity, it’s that it may result in a less disturbed environment in the risk area tomorrow.