Alert archive / Texas / Mesoscale Discussions in 2021
Mesoscale Discussion 777
The Storm Prediction Center issued this mesoscale discussion at May 27, 2021, 6:24 PM CDT for Harmon County, Oklahoma; 39 counties in Texas. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- May 27, 2021, 6:24 PM CDT (23:24 UTC)
- Expired
- May 27, 2021, 8:30 PM CDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe thunderstorm watch 216
All 40 counties
Harmon County, OK, Baylor County, TX, Borden County, TX, Briscoe County, TX, Childress County, TX, Coke County, TX, Collingsworth County, TX, Cottle County, TX, Crane County, TX, Crockett County, TX, Dickens County, TX, Fisher County, TX, Floyd County, TX, Foard County, TX, Glasscock County, TX, Hall County, TX, Hardeman County, TX, Haskell County, TX, Howard County, TX, Irion County, TX, Jones County, TX, Kent County, TX, King County, TX, Knox County, TX, Midland County, TX, Mitchell County, TX, Motley County, TX, Nolan County, TX, Pecos County, TX, Reagan County, TX, Runnels County, TX, Scurry County, TX, Shackelford County, TX, Sterling County, TX, Stonewall County, TX, Taylor County, TX, Terrell County, TX, Throckmorton County, TX, Tom Green County, TX, Upton County, TX
The radar
The Midland/Odessa radar (KMAF), 100 km from the middle of the area, began a volume at 23:26 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 12:00Z, 11.4 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
- 1927 J/kg
- Mixed-layer CIN
- -261 J/kg
- Mixed-layer LCL
- 1145 m above ground
- 0-6 km bulk shear
- 39 kt
- 0-1 km storm-relative helicity
- 246 m²/s²
- 0-3 km storm-relative helicity
- 245 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.3
The text
As transmitted.
868
ACUS11 KWNS 272324
SWOMCD
SPC MCD 272324
TXZ000-OKZ000-280130-
Mesoscale Discussion 0777
NWS Storm Prediction Center Norman OK
0624 PM CDT Thu May 27 2021
Areas affected...Northwest Texas into the Pecos/Rio Grande Valley
vicinity
Concerning...Severe Thunderstorm Watch 216...
Valid 272324Z - 280130Z
The severe weather threat for Severe Thunderstorm Watch 216
continues.
SUMMARY...Widely scattered strong to severe storms, including a few
supercells, will continue to develop through mid to late evening,
posing a risk for large hail and strong surface gusts before
diminishing.
DISCUSSION...Large-scale forcing for ascent appears mostly weak, and
likely to remain so into the evening hours, but weakening
inhibition, due to a combination of insolation and mid-level cold
advection, has allowed for the initiation of scattered thunderstorms
near the dryline.
Along and east of the dryline, a corridor of deep boundary-layer
mixing with sufficient moisture for large CAPE in excess of 3000
J/kg has developed. This has occurred in the presence of strong
deep-layer shear, beneath 30-50+ kt southwesterly flow in the
500-300 mb layer. Low-level wind fields are weak, however, with
little appreciable strengthening forecast, except perhaps in a small
area near the Del Rio, TX vicinity.
Given this environment, a period of continued thunderstorm
intensification appears probable into the 01-03Z time frame, before
the onset of boundary-layer cooling contributes to waning
instability. This may include the evolution of additional isolated
supercells, with strongest storms posing a risk for large hail, and
eventually strong surface gusts before diminishing.
..Kerr.. 05/27/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...FWD...OUN...EWX...SJT...LUB...AMA...MAF...
LAT...LON 32790142 33290106 33870129 34600144 35150003 33149880
31689980 30870095 30230149 29700240 30210275 31080276
32790142SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 26, 7:32 PM CDT | Mesoscale Discussion | SPC | Beaver, Ellis, Harper | 88 min |
| May 26, 11:26 PM CDT | Mesoscale Discussion | SPC | Alfalfa, Beckham, Blaine, Caddo, Canadian, Custer and 20 more | 64 min |
| May 27, 11:04 AM CDT | Mesoscale Discussion | SPC | Adair, Cherokee, Craig, Delaware, Mayes, Nowata and 5 more | 86 min |
| May 27, 11:29 AM CDT | Mesoscale Discussion | SPC | Adair, Alfalfa, Beckham, Blaine, Caddo, Canadian and 39 more | 61 min |
| May 27, 11:58 AM CDT | Tornado Watch | SPC | Adair, Alfalfa, Atoka, Beckham, Blaine, Bryan and 66 more | 9 hr |
| May 27, 1:39 PM CDT | Mesoscale Discussion | SPC | Blaine, Garfield, Grant, Kay, Kingfisher, Logan and 6 more | 66 min |
| May 27, 3:25 PM CDT | Mesoscale Discussion | SPC | Blaine, Canadian, Craig, Creek, Custer, Dewey and 13 more | 95 min |
| May 27, 5:34 PM CDT | Mesoscale Discussion | SPC | Caddo, Cleveland, Comanche, Garvin, Grady, McClain and 2 more | 56 min |
| May 27, 2:50 PM CDT | Mesoscale Discussion | SPC | Borden, Childress, Coke, Collingsworth, Cottle, Crane and 34 more | 115 min |
| May 27, 3:39 PM CDT | Severe Thunderstorm Watch | SPC | Archer, Baylor, Borden, Brewster, Briscoe, Callahan and 46 more | 7 hr |
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.