Alert archive / Oklahoma / Mesoscale Discussions in 2021
Mesoscale Discussion 446
The Storm Prediction Center issued this mesoscale discussion at Apr 28, 2021, 6:35 AM CDT for Washington County, Arkansas; 24 counties in Oklahoma; 15 counties in Texas. It was in force for 3 hr.
The area
The outline as issued.
The facts
- Issued
- Apr 28, 2021, 6:35 AM CDT (11:35 UTC)
- Expired
- Apr 28, 2021, 9:30 AM CDT
- In force
- 3 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Tornado watch 116
All 40 counties
Washington County, AR, Adair County, OK, Atoka County, OK, Carter County, OK, Cherokee County, OK, Coal County, OK, Garvin County, OK, Haskell County, OK, Hughes County, OK, Jefferson County, OK, Johnston County, OK, Latimer County, OK, Love County, OK, Marshall County, OK, McIntosh County, OK, Murray County, OK, Muskogee County, OK, Okfuskee County, OK, Okmulgee County, OK, Pittsburg County, OK, Pontotoc County, OK, Pottawatomie County, OK, Seminole County, OK, Sequoyah County, OK, Wagoner County, OK, Archer County, TX, Callahan County, TX, Clay County, TX, Cooke County, TX, Eastland County, TX, Jack County, TX, Montague County, TX, Palo Pinto County, TX, Parker County, TX, Shackelford County, TX, Stephens County, TX, Taylor County, TX, Throckmorton County, TX, Wise County, TX, Young County, TX
The radar
The Dallas/Ft Worth radar (KFWS), 142 km from the middle of the area, began a volume at 11:37 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
Fort Worth, TX (KFWD), launched 00:00Z, 11.6 hours before the alert went out and 113 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
- 692 J/kg
- Mixed-layer CIN
- -275 J/kg
- Mixed-layer LCL
- 967 m above ground
- 0-6 km bulk shear
- 61 kt
- 0-1 km storm-relative helicity
- 197 m²/s²
- 0-3 km storm-relative helicity
- 388 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.3
The text
As transmitted.
480 ACUS11 KWNS 281135 SWOMCD SPC MCD 281135 ARZ000-OKZ000-TXZ000-281430- Mesoscale Discussion 0446 NWS Storm Prediction Center Norman OK 0635 AM CDT Wed Apr 28 2021 Areas affected...parts of northwest Texas into eastern Oklahoma and northwest Arkansas Concerning...Tornado Watch 116... Valid 281135Z - 281430Z The severe weather threat for Tornado Watch 116 continues. SUMMARY...The threat for severe weather including a tornado or two continues within tornado watch 116. DISCUSSION...Scattered storms persist from the Abilene TX area northeastward into far northwest AR, with a supercell near the OK/AR border in Adair County OK. Meanwhile, a stronger storm cluster was also located over Shackelford County TX, on the southern end of the watch. In between, a large region of rain and thunderstorms covers much of central and southern OK, and extending south of the Red River. While this intermediate region is rain cooled, mid to upper 60s F dewpoints still yield around 1000 J/kg MUCAPE per SFCOA analysis. This early-day warm-advection regime is likely to continue into the late morning as a strong low-level jet maintains lift and theta-e advection. Much of the watch still contains effective SRH on the order of 200-300 m2/s2, favoring an occasional supercell. A brief tornado remains possible, along with localized wind damage or hail. ..Jewell.. 04/28/2021 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...TSA...FWD...OUN...SJT... LAT...LON 32299830 32290037 36199583 36189367 32299830
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 28, 3:01 AM CDT | Tornado Watch | SPC | Benton, Carroll, Crawford, Madison, Washington | 7 hr |
| Apr 28, 8:52 AM CDT | Mesoscale Discussion | SPC | Baxter, Boone, Clay, Cleburne, Conway, Craighead and 17 more | 113 min |
| Apr 28, 9:25 AM CDT | Mesoscale Discussion | SPC | Carroll, Crawford, Madison, Washington | 65 min |
| Apr 28, 10:56 AM CDT | Mesoscale Discussion | SPC | Fulton | 64 min |
| Apr 28, 6:01 PM CDT | Mesoscale Discussion | SPC | Crawford, Franklin, Howard, Logan, Montgomery, Polk and 3 more | 119 min |
| Apr 27, 8:01 PM CDT | Mesoscale Discussion | SPC | Comanche, Cotton, Jefferson, Stephens, Tillman | 89 min |
| Apr 27, 8:23 PM CDT | Severe Thunderstorm Watch | SPC | Carter, Cleveland, Comanche, Cotton, Garvin, Jefferson and 10 more | 7 hr |
| Apr 27, 10:39 PM CDT | Mesoscale Discussion | SPC | Andrews, Borden, Crane, Dawson, Ector, Howard and 5 more | 2 hr |
| Apr 28, 1:38 AM CDT | Mesoscale Discussion | SPC | Callahan, Coke, Coleman, Eastland, Glasscock, Jones and 10 more | 2 hr |
| Apr 28, 1:14 PM CDT | Mesoscale Discussion | SPC | Brown, Callahan, Coleman, Comanche, Cooke, Denton and 14 more | 2 hr |
| Apr 28, 1:57 PM CDT | Tornado Watch | SPC | Brown, Callahan, Coke, Coleman, Comanche, Concho and 16 more | 9 hr |
| Apr 28, 2:42 PM CDT | Mesoscale Discussion | SPC | Bandera, Blanco, Edwards, Gillespie, Kendall, Kerr and 9 more | 2 hr |
| Apr 28, 3:10 PM CDT | Tornado Watch | SPC | Atascosa, Bandera, Bexar, Blanco, Comal, Dimmit and 23 more | 8 hr |
| Apr 28, 3:40 PM CDT | Mesoscale Discussion | SPC | Brown, Callahan, Coleman, Comanche, Eastland, Runnels and 2 more | 95 min |
| Apr 28, 5:41 PM CDT | Mesoscale Discussion | SPC | Bandera, Bexar, Frio, Kendall, Kinney, Maverick and 4 more | 2 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.