Alert archive / Oklahoma / Mesoscale Discussions in 2021
Mesoscale Discussion 345
The Storm Prediction Center issued this mesoscale discussion at Apr 9, 2021, 3:14 PM CDT for 8 counties in Arkansas; 57 counties in Oklahoma; 7 counties in Texas. It was in force for 61 min.
The area
The outline as issued.
The facts
- Issued
- Apr 9, 2021, 3:14 PM CDT (20:14 UTC)
- Expired
- Apr 9, 2021, 4:15 PM CDT
- In force
- 61 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch likely
- Chance of a watch
- 80%
All 72 counties
Benton County, AR, Crawford County, AR, Franklin County, AR, Polk County, AR, Scott County, AR, Sebastian County, AR, Sevier County, AR, Washington County, AR, Adair County, OK, Atoka County, OK, Blaine County, OK, Bryan County, OK, Caddo County, OK, Canadian County, OK, Carter County, OK, Cherokee County, OK, Choctaw County, OK, Cleveland County, OK, Coal County, OK, Comanche County, OK, Cotton County, OK, Craig County, OK, Creek County, OK, Delaware County, OK, Garfield County, OK, Garvin County, OK, Grady County, OK, Haskell County, OK, Hughes County, OK, Jefferson County, OK, Johnston County, OK, Kay County, OK, Kingfisher County, OK, Latimer County, OK, LeFlore County, OK, Lincoln County, OK, Logan County, OK, Love County, OK, Marshall County, OK, Mayes County, OK, McClain County, OK, McCurtain County, OK, McIntosh County, OK, Murray County, OK, Muskogee County, OK, Noble County, OK, Nowata County, OK, Okfuskee County, OK, Oklahoma County, OK, Okmulgee County, OK, Osage County, OK, Ottawa County, OK, Pawnee County, OK, Payne County, OK, Pittsburg County, OK, Pontotoc County, OK, Pottawatomie County, OK, Pushmataha County, OK, Rogers County, OK, Seminole County, OK, Sequoyah County, OK, Stephens County, OK, Tulsa County, OK, Wagoner County, OK, Washington County, OK, Cooke County, TX, Delta County, TX, Fannin County, TX, Grayson County, TX, Lamar County, TX, Montague County, TX, Red River County, TX
The radar
The Norman radar (KTLX), 54 km from the middle of the area, began a volume at 20:16 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, 8.2 hours before the alert went out and 65 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
- 1068 J/kg
- Mixed-layer CIN
- -311 J/kg
- Mixed-layer LCL
- 1414 m above ground
- 0-6 km bulk shear
- 37 kt
- 0-1 km storm-relative helicity
- 28 m²/s²
- 0-3 km storm-relative helicity
- 137 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- -0.6
The text
As transmitted.
996
ACUS11 KWNS 092015
SWOMCD
SPC MCD 092014
ARZ000-TXZ000-MOZ000-OKZ000-KSZ000-092115-
Mesoscale Discussion 0345
NWS Storm Prediction Center Norman OK
0314 PM CDT Fri Apr 09 2021
Areas affected...central and eastern Oklahoma/western Arkansas/North
Texas
Concerning...Severe potential...Watch likely
Valid 092014Z - 092115Z
Probability of Watch Issuance...80 percent
SUMMARY...Eventual storm development expected across this region
will likely require WW issuance late this afternoon.
DISCUSSION...Midday RAOB from KOKC revealed stout capping just above
850 mb, supporting persistent low cloud cover across central
Oklahoma. While the low clouds persist, a slight change in
character toward more cumuliform elements is occurring --
particularly over portions of western/southwestern Oklahoma.
As a cold front continues to advance southeastward across this area,
ahead of a mid-level vort max shifting southeastward out of the High
Plains, ascent will continue to allow the cap to weaken -- resulting
in eventual storm development. Intensity of the initial cells over
far western Oklahoma will likely remain limited, but with 2000 J/kg
mixed-layer CAPE now indicated within the very steep lapse rates
within the elevated mixed layer above the cap, robust storms will
likely evolve.
Storm intensity will be aided by a belt of stronger mid-level flow
expected to spread across the region south/southeast of the upper
system. Along with potential for locally damaging wind gusts, very
large hail will also be possible with the strongest/rotating storms.
..Goss/Thompson.. 04/09/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...LZK...SGF...SHV...TSA...ICT...FWD...OUN...
LAT...LON 35389873 36389838 37019704 37019488 36089383 34429374
33199511 33479796 34439850 35389873SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 9, 9:49 AM CDT | Mesoscale Discussion | SPC | Hempstead, Howard, Lafayette, Little River, Miller, Pike and 1 more | 116 min |
| Apr 9, 12:07 PM CDT | Severe Thunderstorm Watch | SPC | Arkansas, Bradley, Calhoun, Clark, Cleveland, Columbia and 20 more | 6 hr |
| Apr 9, 1:25 PM CDT | Mesoscale Discussion | SPC | Arkansas, Ashley, Bradley, Chicot, Desha, Drew and 5 more | 95 min |
| Apr 9, 2:50 PM CDT | Mesoscale Discussion | SPC | Baxter, Benton, Boone, Carroll, Clay, Cleburne and 18 more | 85 min |
| Apr 9, 3:10 PM CDT | Mesoscale Discussion | SPC | Arkansas, Ashley, Bradley, Chicot, Cleveland, Desha and 5 more | 95 min |
| Apr 9, 3:13 PM CDT | Severe Thunderstorm Watch | SPC | Baxter, Fulton, Izard, Lawrence, Marion, Randolph and 1 more | 7 hr |
| Apr 9, 3:42 PM CDT | Severe Thunderstorm Watch | SPC | Ashley, Chicot, Clay, Craighead, Crittenden, Cross and 6 more | 7 hr |
| Apr 9, 5:19 PM CDT | Mesoscale Discussion | SPC | Ashley | 116 min |
| Apr 9, 5:32 PM CDT | Severe Thunderstorm Watch | SPC | Columbia, Union | 7 hr |
| Apr 9, 6:34 PM CDT | Mesoscale Discussion | SPC | Benton, Carroll, Crawford, Madison, Washington | 116 min |
| Apr 9, 3:55 PM CDT | Severe Thunderstorm Watch | SPC | Adair, Atoka, Bryan, Caddo, Canadian, Carter and 48 more | 7 hr |
| Apr 8, 9:58 PM CDT | Mesoscale Discussion | SPC | Anderson, Brazos, Cherokee, Freestone, Grimes, Henderson and 7 more | 2 hr |
| Apr 9, 3:59 PM CDT | Mesoscale Discussion | SPC | Bastrop, Bell, Blanco, Bosque, Burnet, Caldwell and 14 more | 2 hr |
| Apr 9, 4:27 PM CDT | Severe Thunderstorm Watch | SPC | Anderson, Bell, Bosque, Collin, Cooke, Coryell and 26 more | 9 hr |
Nearby
Mesoscale Discussions in Oklahoma, 2021Mesoscale Discussions in Arkansas, 2021Mesoscale 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.