Alert archive / Texas / Mesoscale Discussions in 2021
Mesoscale Discussion 658
The Storm Prediction Center issued this mesoscale discussion at May 17, 2021, 7:04 PM CDT for 4 counties in Oklahoma; 21 counties in Texas. It was in force for 86 min.
The area
The outline as issued.
The facts
- Issued
- May 17, 2021, 7:04 PM CDT (00:04 UTC)
- Expired
- May 17, 2021, 8:30 PM CDT
- In force
- 86 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch likely
- Chance of a watch
- 95%
All 25 counties
Cotton County, OK, Jefferson County, OK, Stephens County, OK, Tillman County, OK, Archer County, TX, Bosque County, TX, Brown County, TX, Clay County, TX, Comanche County, TX, Eastland County, TX, Erath County, TX, Hamilton County, TX, Hood County, TX, Jack County, TX, Johnson County, TX, Mills County, TX, Montague County, TX, Palo Pinto County, TX, Parker County, TX, Somervell County, TX, Stephens County, TX, Tarrant County, TX, Wichita County, TX, Wise County, TX, Young County, TX
The radar
The Dyess AFB radar (KDYX), 88 km from the middle of the area, began a volume at 00:08 UTC, the scan nearest the moment this went out.
Open the radar archive at this moment
The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.
The watches that followed
Watches SPC issued over any of the same counties within four hours of this discussion.
The nearest sounding before it
Fort Worth, TX (KFWD), launched 00:00Z, 0.1 hours before the alert went out and 100 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.
- Mixed-layer CAPE
- 392 J/kg
- Mixed-layer CIN
- -323 J/kg
- Mixed-layer LCL
- 1247 m above ground
- 0-6 km bulk shear
- 31 kt
- 0-1 km storm-relative helicity
- -57 m²/s²
- 0-3 km storm-relative helicity
- -5 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- -0.1
The text
As transmitted.
469
ACUS11 KWNS 180004
SWOMCD
SPC MCD 180004
TXZ000-OKZ000-180130-
Mesoscale Discussion 0658
NWS Storm Prediction Center Norman OK
0704 PM CDT Mon May 17 2021
Areas affected...North TX...Southwest OK
Concerning...Severe potential...Watch likely
Valid 180004Z - 180130Z
Probability of Watch Issuance...95 percent
SUMMARY...Storms across northwest TX may merge into an
eastward-moving cluster this evening, increasing the severe wind
risk downstream. Watch issuance is likely.
DISCUSSION...At 00Z, intense supercells are ongoing across northwest
TX. Storm coverage continues to gradually increase, and will likely
continue to do so this evening due to cell mergers and gradually
increasing low-level flow. An eastward-moving cluster is expected to
eventually develop, though the exact timing remains uncertain.
MLCINH increases substantially with eastward extent, so storms may
initially struggle to advance to the east until more of a cold pool
becomes established with ongoing convection across northwest TX.
Eventually, a forward-propagating system is expected to move into
portions of southwest OK and north-central TX, with a primary risk
of damaging wind, though large hail will also continue to be
possible with the strongest updrafts. Watch issuance may be needed
by 01Z to cover this threat.
..Dean/Grams.. 05/18/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...FWD...OUN...SJT...
LAT...LON 31539927 33309890 34689915 34519767 33629727 32699716
31849736 31609783 31489850 31439909 31539927SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 17, 7:23 PM CDT | Mesoscale Discussion | SPC | Beaver, Cimarron, Texas | 2 hr |
| May 17, 9:28 PM CDT | Mesoscale Discussion | SPC | Beaver, Beckham, Cimarron, Ellis, Roger Mills, Texas | 2 hr |
| May 18, 2:30 PM CDT | Mesoscale Discussion | SPC | Choctaw, McCurtain | 2 hr |
| May 18, 3:51 PM CDT | Severe Thunderstorm Watch | SPC | LeFlore, McCurtain | 5 hr |
| May 17, 7:32 PM CDT | Tornado Watch | SPC | Brown, Callahan, Coke, Coleman, Concho, McCulloch and 4 more | 3 hr |
| May 17, 7:37 PM CDT | Mesoscale Discussion | SPC | Callahan, Coke, Coleman, Glasscock, Howard, Jones and 6 more | 83 min |
| May 17, 8:04 PM CDT | Severe Thunderstorm Watch | SPC | Archer, Clay, Comanche, Eastland, Erath, Hamilton and 11 more | 5 hr |
| May 17, 8:34 PM CDT | Mesoscale Discussion | SPC | Atascosa, Dimmit, Frio, La Salle, McMullen, Maverick and 2 more | 116 min |
| May 17, 9:44 PM CDT | Mesoscale Discussion | SPC | Armstrong, Borden, Briscoe, Childress, Collingsworth, Cottle and 15 more | 91 min |
| May 17, 10:23 PM CDT | Mesoscale Discussion | SPC | Archer, Brown, Callahan, Clay, Coke, Coleman and 16 more | 97 min |
| May 17, 10:35 PM CDT | Mesoscale Discussion | SPC | Andrews, Borden, Brewster, Crane, Crockett, Dawson and 13 more | 85 min |
| May 17, 10:58 PM CDT | Severe Thunderstorm Watch | SPC | Andrews, Borden, Brown, Coke, Coleman, Concho and 22 more | 7 hr |
| May 17, 11:37 PM CDT | Mesoscale Discussion | SPC | Bosque, Brown, Comanche, Denton, Eastland, Erath and 9 more | 83 min |
| May 18, 1:02 AM CDT | Mesoscale Discussion | SPC | Brooks, Duval, Jim Hogg | 58 min |
| May 18, 1:29 AM CDT | Mesoscale Discussion | SPC | Coke, Concho, Crane, Crockett, Ector, Glasscock and 13 more | 91 min |
| May 18, 5:07 AM CDT | Mesoscale Discussion | SPC | Coke, Concho, Irion, Reagan, Runnels, Schleicher and 2 more | 53 min |
| May 18, 1:18 PM CDT | Mesoscale Discussion | SPC | Atascosa, Austin, Bastrop, Bexar, Brazos, Burleson and 28 more | 117 min |
| May 18, 1:57 PM CDT | Mesoscale Discussion | SPC | Bailey, Castro, Deaf Smith, Parmer, Randall, Swisher | 3 hr |
| May 18, 2:29 PM CDT | Tornado Watch | SPC | Anderson, Atascosa, Austin, Bastrop, Bexar, Blanco and 30 more | 7 hr |
| May 18, 3:52 PM CDT | Mesoscale Discussion | SPC | Bastrop, Caldwell, Colorado, Fayette, Gonzales, Guadalupe and 2 more | 83 min |
| May 18, 5:10 PM CDT | Mesoscale Discussion | SPC | La Salle, McMullen, Webb | 95 min |
| May 18, 5:39 PM CDT | Mesoscale Discussion | SPC | Bowie, Cass, Gregg, Harrison, Marion, Morris and 1 more | 2 hr |
| May 18, 6:07 PM CDT | Mesoscale Discussion | SPC | Armstrong, Borden, Briscoe, Carson, Castro, Cochran and 17 more | 113 min |
| May 18, 6:13 PM CDT | Mesoscale Discussion | SPC | Austin, Brazos, Burleson, Colorado, DeWitt, Fayette and 14 more | 92 min |
Nearby
Mesoscale Discussions in Texas, 2021Mesoscale Discussions in Oklahoma, 2021Every mesoscale discussion in 2021
Sources
The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.