2019-05-24 EVENT: IA/IL/KS/MO/OK/TX

Jun 16, 2015
407
867
21
32
Oklahoma City, OK
quincyvagell.com
After having relatively isolated targets for much of this week, Friday's severe weather threat looks to cover a wide area with many possible targets.

Synoptically, a ridge will be in place over the Southeast with a seasonably strong upper level jet ejecting from the Central Plains into the Upper Midwest. The most apparent region for severe thunderstorm development and chase prospects will be on the southeast fringe of the stronger upper level winds, where they juxtapose with moderate to locally strong instability.

Plains targets:
This area is hard to pin down. Due to minimal convective inhibition, most model solutions initiate a band of convection by midday to early afternoon over a broad area. Mixed modes are probable, although the overall signal is fairly messy. Depending on convective evolution, you might have embedded supercells, or there could be fairly quick upscale growth. It's hard to pin down specific target areas at this time, but they should become more clear by morning. If convective trends dial back a bit, there a more robust severe threat, at least locally, could evolve. Another scenario is that early day convection over the Southern High Plains/Oklahoma/Kansas vicinity moves east and there is just enough recovery in the afternoon for isolated storm development in its wake. If this does occur, look for any outflow boundaries. My guess is that if this scenario does happen, you'd be most likely to look somewhere from the Texas Panhandle vicinity into northwestern Oklahoma and south-central Kansas, but that's just speculation. Another area to look may be on the southwestern fringe of early day convection, which might set up somewhere around the Texas South Plains. There's also a dryline forecast to be in place across West/Southwest Texas, but model solutions are varied with this feature. That area will be displaced from more favorable shear to the north and HRRR progs show virtually no SRH, outside of the storm-scale level. Some recent model runs have popped up the classic I-10 lone storm around 00z, but that seems like a risky play, especially given less than stellar wind profiles.

Midwest target:
I think as we get closer in, this appears to be the most intriguing target, assuming it's within driving range. Most convection allowing models show substantial destabilization along and south of a warm front, draped from Iowa into northern Illinois. Wind profiles show quite a bit of turning with height and hodographs will be largest in vicinity of the warm front. If convective initiation holds off until at least mid-afternoon, then you'd probably see supercell storm development in the eastern Iowa/northern Illinois vicinity with a few intense updrafts possible. The model consensus is for a relative minimum in severe potential across Missouri, but it's possible that the warm front lingers close enough that a few storms could affect northeastern Missouri. On the other hand, any storms ejecting from southeastern Kansas could move into Missouri as well.

Keep in mind that northern Oklahoma and southern Kansas are extremely wet and additional rainfall may exacerbate flooding issues here. Dirt roads are quite muddy over much of the area with many roads impassible, even including some paved roads. Keep this in mind if you plan on targeting that area.
 

chrisbray

EF4
Apr 24, 2012
471
125
11
Bourbonnais, Illinois
Agree and I plan on heading out towards quad cities this morning. The I-80 and I-88 corridors seems like the best target, but the MCS that just passed through Des Moines doesn't seem to be weakening and has me a bit worried about cloud cover in the warm sector. Guess we will wait and see how far the warm front lifts and finding any destabilization chances near it.
 
  • Like
Reactions: Jason Strohecker

Jesse Risley

Staff member
Apr 12, 2006
1,941
239
11
38
Macomb, IL
www.tornadoguys.com
I've been keeping an eye on the frontal position here in the Central Plains region, as it currently lies south of the ongoing convection, roughly south of US 136 and then back NW-SE across Central IL. I'd expect it to lift north, as the models have indicated, once the current MCS exits eastern IA and begins to further decay. The key here will be afternoon destabilization of the warm sector. As always with these types of setups, besides the position of the frontal boundary, there is also the mesoscale aspect of monitoring the position of OFBs from the ongoing convection that should continue to move eastward towards the Mississippi River into north central Illinois. CAMs have been consistent for the past 24 hours or so igniting convection proximal to the warm front during the late afternoon, as the next perturbation aloft overspreads eastern Iowa as highlighted by progged H5 absolute vort.

If the environment can adequately destablize, the discrete convection across far E IA is likely to interact with the warm front and potentially remnant OFBs to enhance tornadic potential. Though some of the overall lower level shear profiles are closer to being marginal, SRH and LCLs are favorable for some tornadic supercells, and mesoscale interactions can enhance near-storm vorticity at the surface. More corpulent looking CAPE values within the -10 to -30° C layer and large boundary layer moisture, coupled with ambient 700-500 mb lapse rates > 7.0 C km-1, suggest some large hail reports are likely to come fruition. If moderate to large CAPE values materialize, given steeper low-level/sub-cloud lapse rates, boundary layer moisture values, and 850-500 mb lapse rate ≥ 7.6 C km-1 (per morning RAP soundings), damaging wind reports are likely today as well.

The latest 12z HRRR is indicating more of a quick evolution to a linear mode between I-80 and I-88 once convection gets into IL. While there is ample turning in the lowest 1km and progged critical angles on soundings are favorable for tornadic development if storms can maintain favorable trajectories, profiles aloft are also quasi-unidirectional.
 
  • Like
Reactions: Ethan Schisler
Sep 25, 2006
482
52
11
29
Minneapolis, MN
Looks like there are some breaks in the clouds behind the MCS in IA. The problem is there is more rain and clouds moving northeast out of KS/NE towards IA that will probably cause issues with heating and destabilization this afternoon. HRRR wants to keep deeper convection and better UH tracks farther east into IL. I'd like to see that come west into IA before I pull the trigger on chasing today. I personally will be watching the HRRR closely this morning and as much as I hate to do it I will probably be basing my decision about chasing on what the HRRR shows because today is such a messy forecast. If we can get enough heating in eastern IA into IL I think there is a roughly 2 hour window of decent tornado potential.
 
Sep 25, 2006
482
52
11
29
Minneapolis, MN
There could be a threat for some mini supercells south of Fargo along the ND/MN border. NAM, 3km NAM, and HRRR all support this threat. A small corridor of higher parameters looks like it could materialize near a diffuse warm front/cold front intersection from a low pressure system moving through the area. Not sure how legit the threat is but it will be interesting to see if anything comes of it.
 
Jun 16, 2015
407
867
21
32
Oklahoma City, OK
quincyvagell.com
The MCS exiting Iowa and heading toward Illinois/Wisconsin is a bit concerning, as it looks a bit more expansive than even recent runs of the HRRR have shown. It is still relatively early, so I wouldn't say it's game ending for the warm front threat.

The southern High Plains target is looking increasingly favorable. Radar imagery this morning shows only a fine line of precipitation along a SW/NE axis between Amarillo and Lubbock. This boundary will separate a cooler/less unstable air mass from an increasingly unstable air mass to the south and east. The only issue I have right away is that the boundary, which will probably be a main focus point for storm initiation, is once again oriented nearly parallel to the deep shear vectors.

As far as shear goes, wind profiles will improve somewhat, but mainly not until late afternoon. Right now, the low-level jet is displaced well east of the area and there is some veer-backing of 1-3km winds observed across the West Texas/panhandle vicinity. With time, the low-level jet should increase and high resolution guidance shows enlargement of hodographs right around 00z.

For storm initiation, a mixed storm mode seems probable from West Texas toward the OK/TX border area, but at least a few discrete/semi-discrete storms should evolve. Any storms that remain at least somewhat isolated toward 23-02z would have a modest tornado threat.

Between the two areas, across Oklahoma and toward southern/eastern Kansas and western Missouri, wind profiles are not particularly ideal for supercells. While you may have a few such storms, hodograph size looks relatively limited. Again, this will improve a bit toward early evening, but a relatively low, although non-zero tornado threat is probable between the more interesting targets in Texas and Illinois/Iowa. Look for any storms that interact with ongoing/leftover boundaries for a possible tornado.

It does not look like a big a day, especially with smoke being a major issue, particularly over Oklahoma/Texas. I could see why some chasers might sit this one out, but if there's patience and determination, I do think there will be at least a few storms to chase in multiple target areas.
 
  • Like
Reactions: Brian McKibben

Dan Robinson

WxLibrary Editor
Staff member
Jan 14, 2011
2,346
1,958
21
St. Louis
stormhighway.com
Chaser alert: east-west road that passes through Owings south of Crosbyton is rapidly flooding. I had to turn around. Flooding situation east of Lubbock has reached dangerous levels for chasers. High risk of getting trapped by rising water. Must stay out of heavy precip/core punch moves.
 
  • Like
Reactions: Todd Lemery