Alert archive / Texas / Mesoscale Discussions in 2021

Mesoscale Discussion 668

May 18, 202119 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at May 18, 2021, 1:29 AM CDT for 19 counties in Texas. It was in force for 91 min.

The area

The outline as issued.

The facts

Issued
May 18, 2021, 1:29 AM CDT (06:29 UTC)
Expired
May 18, 2021, 3:00 AM CDT
In force
91 min
Issued by
the Storm Prediction Center
Concerning
Severe thunderstorm watch 187

Counties Coke County, TX, Concho County, TX, Crane County, TX, Crockett County, TX, Ector County, TX, Glasscock County, TX, Howard County, TX, Irion County, TX, Menard County, TX, Midland County, TX, Mitchell County, TX, Pecos County, TX, Reagan County, TX, Runnels County, TX, Schleicher County, TX, Sterling County, TX, Sutton County, TX, Tom Green County, TX, Upton County, TX

The radar

The San Angelo radar (KSJT), 68 km from the middle of the area, began a volume at 06:29 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 nearest sounding before it

Midland Regional, TX (KMAF), launched 00:00Z, 6.5 hours before the alert went out and 106 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.

Skew-T log-pSkew-T log-p diagram, Midland Regional, TX at 00:00Z on 2021-05-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 953 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Midland Regional, TX at 00:00Z on 2021-05-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 5 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
953 J/kg
Mixed-layer CIN
-44 J/kg
Mixed-layer LCL
1920 m above ground
0-6 km bulk shear
25 kt
0-1 km storm-relative helicity
5 m²/s²
0-3 km storm-relative helicity
36 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.8

Open this sounding in Storm Lab

The text

As transmitted.

423 
ACUS11 KWNS 180630
SWOMCD
SPC MCD 180629 
TXZ000-180800-

Mesoscale Discussion 0668
NWS Storm Prediction Center Norman OK
0129 AM CDT Tue May 18 2021

Areas affected...portions of southwest TX

Concerning...Severe Thunderstorm Watch 187...

Valid 180629Z - 180800Z

The severe weather threat for Severe Thunderstorm Watch 187
continues.

SUMMARY...Additional thunderstorms are expected to develop over
western portions of WW 187 over the next hour or two. Large hail
will be the main threat, but locally damaging gusts also could
occur.

DISCUSSION...A deepening line of cumulus has been noted in the
GOES-16 nighttime microphysics product over the past 30 minutes or
so from just northwest of Ft. Stockton to just south of Midland.
Most recently, weak midlevel reflectivity cores have become evident
in regional radar as well. This activity is developing to the east
of a dryline in moist upslope low level flow and to the south of an
outflow boundary. Strong instability, with MLCAPE values from
1500-3500 J/kg are in place, and very steep midlevel lapse rates
greater than 8 C/km remain over the region amid effective shear
greater than 40 kt and a 30+ kt southerly low level jet. This should
support organized, somewhat elevated supercells. Large hail and
locally strong gusts could accompany these cells.

..Leitman.. 05/18/2021

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...SJT...MAF...

LAT...LON   32059994 31359942 30470014 30310186 30530291 31270297
            31940284 32320190 32400120 32350075 32100006 32059994

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
May 17, 7:04 PM CDTMesoscale DiscussionSPCArcher, Bosque, Brown, Clay, Comanche, Eastland and 15 more86 min
May 17, 7:23 PM CDTMesoscale DiscussionSPCCarson, Dallam, Gray, Hansford, Hartley, Hemphill and 8 more2 hr
May 17, 7:32 PM CDTTornado WatchSPCBrown, Callahan, Coke, Coleman, Concho, McCulloch and 4 more3 hr
May 17, 7:37 PM CDTMesoscale DiscussionSPCCallahan, Coke, Coleman, Glasscock, Howard, Jones and 6 more83 min
May 17, 8:04 PM CDTSevere Thunderstorm WatchSPCArcher, Clay, Comanche, Eastland, Erath, Hamilton and 11 more5 hr
May 17, 8:34 PM CDTMesoscale DiscussionSPCAtascosa, Dimmit, Frio, La Salle, McMullen, Maverick and 2 more116 min
May 17, 9:28 PM CDTMesoscale DiscussionSPCCarson, Collingsworth, Donley, Gray, Hansford, Hemphill and 7 more2 hr
May 17, 9:44 PM CDTMesoscale DiscussionSPCArmstrong, Borden, Briscoe, Childress, Collingsworth, Cottle and 15 more91 min
May 17, 10:23 PM CDTMesoscale DiscussionSPCArcher, Brown, Callahan, Clay, Coke, Coleman and 16 more97 min
May 17, 10:35 PM CDTMesoscale DiscussionSPCAndrews, Borden, Brewster, Crane, Crockett, Dawson and 13 more85 min
May 17, 10:58 PM CDTSevere Thunderstorm WatchSPCAndrews, Borden, Brown, Coke, Coleman, Concho and 22 more7 hr
May 17, 11:37 PM CDTMesoscale DiscussionSPCBosque, Brown, Comanche, Denton, Eastland, Erath and 9 more83 min
May 18, 1:02 AM CDTMesoscale DiscussionSPCBrooks, Duval, Jim Hogg58 min
May 18, 5:07 AM CDTMesoscale DiscussionSPCCoke, Concho, Irion, Reagan, Runnels, Schleicher and 2 more53 min
May 18, 1:18 PM CDTMesoscale DiscussionSPCAtascosa, Austin, Bastrop, Bexar, Brazos, Burleson and 28 more117 min
May 18, 1:57 PM CDTMesoscale DiscussionSPCBailey, Castro, Deaf Smith, Parmer, Randall, Swisher3 hr
May 18, 2:29 PM CDTTornado WatchSPCAnderson, Atascosa, Austin, Bastrop, Bexar, Blanco and 30 more7 hr
May 18, 2:30 PM CDTMesoscale DiscussionSPCBowie, Camp, Cass, Cherokee, Franklin, Gregg and 12 more2 hr
May 18, 3:51 PM CDTSevere Thunderstorm WatchSPCBowie, Camp, Cass, Cherokee, Franklin, Gregg and 11 more5 hr
May 18, 3:52 PM CDTMesoscale DiscussionSPCBastrop, Caldwell, Colorado, Fayette, Gonzales, Guadalupe and 2 more83 min
May 18, 5:10 PM CDTMesoscale DiscussionSPCLa Salle, McMullen, Webb95 min
May 18, 5:39 PM CDTMesoscale DiscussionSPCBowie, Cass, Gregg, Harrison, Marion, Morris and 1 more2 hr
May 18, 6:07 PM CDTMesoscale DiscussionSPCArmstrong, Borden, Briscoe, Carson, Castro, Cochran and 17 more113 min
May 18, 6:13 PM CDTMesoscale DiscussionSPCAustin, Brazos, Burleson, Colorado, DeWitt, Fayette and 14 more92 min

Nearby

Mesoscale Discussions in Texas, 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.