Alert archive / Oklahoma / Mesoscale Discussions in 2021
Mesoscale Discussion 764
The Storm Prediction Center issued this mesoscale discussion at May 27, 2021, 11:29 AM CDT for Crawford County, Arkansas; 45 counties in Oklahoma; Collingsworth County, Hemphill County, Wheeler County, Texas. It was in force for 61 min.
The area
The outline as issued.
The facts
- Issued
- May 27, 2021, 11:29 AM CDT (16:29 UTC)
- Expired
- May 27, 2021, 12:30 PM CDT
- In force
- 61 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch likely
- Chance of a watch
- 80%
All 49 counties
Crawford County, AR, Adair County, OK, Alfalfa County, OK, Beckham County, OK, Blaine County, OK, Caddo County, OK, Canadian County, OK, Cherokee County, OK, Cleveland County, OK, Creek County, OK, Custer County, OK, Dewey County, OK, Ellis County, OK, Garfield County, OK, Grady County, OK, Grant County, OK, Greer County, OK, Haskell County, OK, Hughes County, OK, Kay County, OK, Kingfisher County, OK, Lincoln County, OK, Logan County, OK, Major County, OK, Mayes County, OK, McClain County, OK, McIntosh County, OK, Muskogee County, OK, Noble County, OK, Okfuskee County, OK, Oklahoma County, OK, Okmulgee County, OK, Osage County, OK, Pawnee County, OK, Payne County, OK, Pottawatomie County, OK, Roger Mills County, OK, Rogers County, OK, Seminole County, OK, Sequoyah County, OK, Tulsa County, OK, Wagoner County, OK, Washington County, OK, Washita County, OK, Woods County, OK, Woodward County, OK, Collingsworth County, TX, Hemphill County, TX, Wheeler County, TX
The radar
The Norman radar (KTLX), 75 km from the middle of the area, began a volume at 16:31 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
Norman, OK (KOUN), launched 12:00Z, 4.5 hours before the alert went out and 92 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
- 2431 J/kg
- Mixed-layer CIN
- -121 J/kg
- Mixed-layer LCL
- 765 m above ground
- 0-6 km bulk shear
- 43 kt
- 0-1 km storm-relative helicity
- 264 m²/s²
- 0-3 km storm-relative helicity
- 360 m²/s²
- Significant tornado parameter
- 1.5
- Supercell composite
- 7.5
The text
As transmitted.
203
ACUS11 KWNS 271630
SWOMCD
SPC MCD 271629
ARZ000-OKZ000-KSZ000-TXZ000-271730-
Mesoscale Discussion 0764
NWS Storm Prediction Center Norman OK
1129 AM CDT Thu May 27 2021
Areas affected...eastern Texas Panhandle...Oklahoma. far southern
Kansas and northwest Arkansas
Concerning...Severe potential...Watch likely
Valid 271629Z - 271730Z
Probability of Watch Issuance...80 percent
SUMMARY...Thunderstorms are expected to develop across western
through central Oklahoma by early afternoon and gradually spread
east. Supercells with isolated large hail will be the initial main
threat, but isolated damaging wind and a few tornadoes are also
possible.
DISCUSSION...Latest objective analysis show the atmosphere to be
moderately to strongly unstable (2500-3000 J/kg MLCAPE) across
western through central OK supported by steep mid-level lapse rates
above rich low-level moisture with surface dewpoints in the low 70s
F. Latest trends in radar show a few showers developing within a
modest warm advection regime in the pre-frontal warm sector across
western OK. While some remnant capping may still exist, convective
inhibition should gradually weaken as temperatures rise into the low
80s F. Rap analysis data show a mid-level jet approaching this
region from the west, and effective bulk shear profiles will
gradually increase to between 40 and 50 kt through the afternoon.
This environment should support discrete supercells as the initial
storm mode with large to very large hail likely. While low-level
hodographs are not particularly large with 0-1 km storm relative
helicity between 100-150 m2/s2 isolated tornadoes cannot be ruled
out given degree of instability and a very moist boundary layer with
relatively low LCLS. Additional storms may develop along the cold
front by late afternoon across southern KS into northern OK and
these will also likely become severe.
..Dial/Hart.. 05/27/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...TSA...ICT...OUN...DDC...AMA...
LAT...LON 35579377 34959538 34920033 36260026 37099842 36719549
35579377SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 27, 11:04 AM CDT | Mesoscale Discussion | SPC | Baxter, Benton, Boone, Carroll, Cleburne, Crawford and 15 more | 86 min |
| May 27, 2:06 PM CDT | Mesoscale Discussion | SPC | Baxter, Boone, Clay, Cleburne, Conway, Craighead and 23 more | 84 min |
| May 27, 4:52 PM CDT | Mesoscale Discussion | SPC | Arkansas, Baxter, Benton, Boone, Carroll, Clark and 47 more | 83 min |
| May 27, 5:12 PM CDT | Severe Thunderstorm Watch | SPC | Arkansas, Baxter, Benton, Boone, Carroll, Clark and 41 more | 8 hr |
| May 27, 5:21 PM CDT | Mesoscale Discussion | SPC | Clay, Craighead, Greene, Mississippi | 114 min |
| 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, 11:58 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, 6:24 PM CDT | Mesoscale Discussion | SPC | Harmon | 2 hr |
| 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 Oklahoma, 2021Mesoscale Discussions in Texas, 2021Mesoscale Discussions in Arkansas, 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.