Severe Weather May 20-25, 27th, 2020

[Chinook]

Supercells are popping up all over the place near Fort Smith AR.

[Buckeye05]

Seeing pictures of fairly substantial structural damage in Bowie, TX including roof and exterior wall loss. Also hearing reports of mobile homes completely destroyed in town. Not good.

[cheese007]

Storms weakening a bit as they head into the metro

[jojo762]

4 hours ago, BrandonC_TX said:

Tornado warning also issued for that storm just northwest of Wichita Falls.  Radar indicated at this time.

EDIT: confirmed tornado west of Burkburnett according to livestream from Channel 6 in Wichita Falls.

Was on this storm from initiation onward until it merged into a blob near sunset. Wrapped up really nicely numerous times, produced numerous dusty tornadoes that weren’t fully condensated. Really thought it was going to produce something more significant at least a couple times — but it never could quite get it going. RFD was quite strong, but perhaps not warm/moist enough — and the inflow wasn’t all that strong really. 
 

On to tomorrow which offers a wide range of targets... most of which are probably too far from Wichita Falls to actually chase. 
 

Looking like Sunday could possibly be the last “severe day” the plains have for a while.

[Chinook]

This video has been making the rounds on Twitter -- a great funnel and debris cloud. I don't know how wide this is, but it's obviously not a wedge. So I guess that's kind of good, less total damage.

[Quincy]

Fairly high confidence in a corridor with intense supercell potential from northeastern Colorado into southwestern Nebraska on the nose of a lee cyclone. The parameter space should become very favorable toward and just after 00z for a couple of tornadoes. Forecast soundings show enlarging hodographs and more than ample instability.

I wouldn’t be surprised if SPC adds a small ENH risk area, but then again, they’re not predicting for storm chasers. 

The environment in northwestern Kansas also looks conditionally favorable for an intense supercell, but capping and less focused forcing lead to some uncertainty there.

[WhirlingWx]

TOG in Garza County, TX, SW of the town of Post, had/has a PDS on it. I believe that's the first PDS this month? Looking like it'll stay south of Post itself

[Chinook]

confirmed tornado near Post, Texas.

large and extremely dangerous tornado was located 11 miles southeast of Grassland, or 13 miles southwest of 
Post

The base velocity looks kind of awesome on this one.

[Snowstorm920]

Some wild velocity signatures with that cell near Post 

[Chinook]

This storm may have had two simultaneous tornadoes, but if not, this is still kind of a crazy velocity image

[WhirlingWx]

The PDS tornadic supercell in Texas is basically stationary, and in a localized area favorable for it to keep cranking

[WhirlingWx]

And meanwhile, in a marginal and general t-storm area...

The NWS Storm Prediction Center has issued a

   * Tornado Watch for portions of 
     Extreme northeast and east central Colorado
     Northwest Kansas
     Extreme southwest Nebraska

   * Effective this Saturday afternoon and evening from 435 PM until
     1000 PM MDT.

   * Primary threats include...
     A couple tornadoes possible
     Scattered large hail and isolated very large hail events to 2.5
       inches in diameter possible
     Isolated damaging wind gusts to 70 mph possible

   SUMMARY...Thunderstorm development appears to be underway near a
   mesolow along the dryline near Goodland.  At least isolated
   supercells should evolve from this initial convection, with the
   potential to produce isolated very large hail and a couple of
   tornadoes through late evening.

[Quincy]

The environment near the western KS/NE border is going to rapidly become very favorable for tornadoes around and after 7 p.m. Let’s see what happens. 

[Quincy]

Current storm NW of Goodland is still displaced a bit too far west of an area with much better low-level moisture to the east. I’m watching it and it’s still somewhat elevated and attempting to organize. If it can hang on for another 60-90 minutes, then the tornado threat will begin to substantially increase. 

[Chinook]

Today has certainly had some excitement, with 6 zones of severe weather.

[Quincy]

Just now, Chinook said:

Today has certainly had some excitement, with 6 zones of severe weather.

Late May has a way of squeaking out severe, even if regional (or even local patterns) don’t look particularly favorable. Yesterday had some sneaky severe reports too. 

[jojo762]

3 hours ago, Quincy said:

Current storm NW of Goodland is still displaced a bit too far west of an area with much better low-level moisture to the east. I’m watching it and it’s still somewhat elevated and attempting to organize. If it can hang on for another 60-90 minutes, then the tornado threat will begin to substantially increase. 

Funny how tons of chasers (myself included) get sucked into NW KS after being near Wichita Falls yesterday by a few HRRR runs... should’ve been obvious things were going to struggle given the initiation location relative to the moisture axis as well as the warm 700mb temps.

Most well documented rain shower of all time.

[Quincy]

I'm not sure where the warm 700mb idea came from, but several people have been mentioning it on Twitter and elsewhere. 700mb temperatures were around +10C when I looked this afternoon and there wasn't much of a capping inversion in place. However, an area of CINH was analyzed over northwestern Kansas, likely a result of clouds limiting surface heating and somewhat lower dew points than forecast. Note that convective temperatures in northwestern Kansas were in the lower 80s, but temperatures struggled to get above the mid/upper 70s.

I've spent the past hour and a half writing a post mortem about this:

 

[NWOkie_124]

We had some high winds come through Thursday night.  Naturally I was out of town and missed it.  The storms blew off some tin from my shed and uprooted a very large tree a few blocks north of me.

[jojo762]

00z LBF sounding did show a pretty stout cap at ~700mb last night... so probably a combo of both a several degree bust on forecast surface moisture and heating AND a traditional capping inversion.

[Quincy]

An inversion is defined as temperatures rising with increasing height. A capping inversion usually refers to a stable layer above the boundary layer where temperatures rise. 

The 00z LBF sounding does show a cap with -76 J/kg MLCIN. This is a good example of a traditional cap:

Refer to a 2hr near term RAP sounding valid at 23z near Goodland, KS. There’s about the same amount of MLCIN (-72 J/kg), but there is no capping inversion. The cause for CIN is largely tied to relatively dry boundary layer air. The convective temperature is 85F, but forecast and actual temperatures were only in the upper 70s.

For some reason this year the default explanation for any severe event not panning out is that there was a cap. I just don’t see a cap last night over northwestern Kansas. 

I had some good dialogue last night on Twitter about the bust. In addition to cloud cover, limited surface heating and dry air, the evolution of the dryline was key as well. As the dryline bulged, it actually curled in on itself. Not only did this feed drier air north, but it caused shear vector orientation issues. Instead of deep shear vectors being oriented orthogonally with the dryline, messy angles and lazy storm motions prevented parcels from ingesting more favorable moist low-level air that was displaced to the northeast. 

[Chinook]

pretty cool pic/video from near Post, TX

[Quincy]

Extended the thread for one more day. Today looks like a broad area with multiple targets, while tomorrow is a bit more focused on central/western Texas. Beyond tomorrow, the pattern across most of the Plains looks relatively benign for late May standards. 

[cheese007]

Severe thunderstorm warning for Denton County in TX

[Quincy]

Currently chasing this hail-producing supercell that is moving from Baca County, Colorado toward the Kansas border. 

 

[mob1]

Interesting little feature entering the northern suburbs of San Antonio. 

[bjenkins]

Noticed a lack of quality video from Bellevue/Joy TX tornado (5/22) so figured you guys would appreciate. Don't share often but this tor just didn't have very many witnesses. A nice ending to a rather lackluster May. We peeled off about halfway to the Red River storm after watching the southern updrafts mature and sustain, this happened shortly after the two cells merged and the southern became dominant. Enjoy. 

 

[Quincy]

Chased a supercell near Del Rio, TX today. Saw some robust updrafts on the Mexico side of the border, but this storm was the one I was focused on:

One of the rare chases south of I-10 that actually produced something worth chasing. 

[stormdragonwx]

I know its outside of the range for this discussion thread but does anyone have thoughts on the TX setup for tomorrow? Trying to make the most of this lackluster season and since I am off work till Friday I'm considering taking a shot at it even if it is a 12 hour drive one way. Though the pattern looks to be about the same as its been this year with messy HP storm modes and SSE storm motions from my initial look at the models. Either way I'm surprised there hasn't been more talk on this setup.

[Quincy]

3 hours ago, stormdragonwx said:

I know its outside of the range for this discussion thread but does anyone have thoughts on the TX setup for tomorrow? Trying to make the most of this lackluster season and since I am off work till Friday I'm considering taking a shot at it even if it is a 12 hour drive one way. Though the pattern looks to be about the same as its been this year with messy HP storm modes and SSE storm motions from my initial look at the models. Either way I'm surprised there hasn't been more talk on this setup.

This setup kind of went under the radar until SPC upgraded. I’ve been watching it. Some people have mentioned “veering” winds, but upper level winds look NW. Theres actually quite a bit of turning with some forecast soundings showing NW 500mb winds backing to SSE near the surface. The hodograph is rotated almost 90 degrees from a “typical” late May event in central Texas. 

I need to take a closer look with 00z guidance tonight, so far it looks like CI may occur relatively early in central Texas, but the environment gets increasingly favorable by late afternoon. I’d probably watch the tail end storm and there are is even a conditional threat for SW Texas (maybe down near I-10) could see an intense storm or two early in the evening. At least based on the parameter space, if the cap can be broken. Storm modes are probably going to be messy toward the N/NE edge of the risk area.