Alert archive / Oklahoma / Mesoscale Discussions in 2021
Mesoscale Discussion 509
The Storm Prediction Center issued this mesoscale discussion at May 3, 2021, 7:38 PM CDT for 13 counties in Oklahoma; 12 counties in Texas. It was in force for 97 min.
The area
The outline as issued.
The facts
- Issued
- May 3, 2021, 7:38 PM CDT (00:38 UTC)
- Expired
- May 3, 2021, 9:15 PM CDT
- In force
- 97 min
- Issued by
- the Storm Prediction Center
- Concerning
- Tornado watch 133
All 25 counties
Atoka County, OK, Bryan County, OK, Choctaw County, OK, Coal County, OK, Haskell County, OK, Hughes County, OK, Johnston County, OK, Latimer County, OK, Marshall County, OK, McIntosh County, OK, Pittsburg County, OK, Pontotoc County, OK, Pushmataha County, OK, Bosque County, TX, Collin County, TX, Dallas County, TX, Denton County, TX, Ellis County, TX, Fannin County, TX, Grayson County, TX, Hill County, TX, Johnson County, TX, Rockwall County, TX, Somervell County, TX, Tarrant County, TX
The radar
The Dallas/Ft Worth radar (KFWS), 90 km from the middle of the area, began a volume at 00:39 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
Fort Worth, TX (KFWD), launched 00:00Z, 0.6 hours before the alert went out and 66 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
- 3299 J/kg
- Mixed-layer CIN
- -10 J/kg
- Mixed-layer LCL
- 1213 m above ground
- 0-6 km bulk shear
- 58 kt
- 0-1 km storm-relative helicity
- 150 m²/s²
- 0-3 km storm-relative helicity
- 143 m²/s²
- Significant tornado parameter
- 2.6
- Supercell composite
- 13.9
The text
As transmitted.
299
ACUS11 KWNS 040039
SWOMCD
SPC MCD 040038
OKZ000-TXZ000-040215-
Mesoscale Discussion 0509
NWS Storm Prediction Center Norman OK
0738 PM CDT Mon May 03 2021
Areas affected...Portions of central/north-central TX into
southern/eastern OK
Concerning...Tornado Watch 133...
Valid 040038Z - 040215Z
The severe weather threat for Tornado Watch 133 continues.
SUMMARY...A large hail threat continues in the short term, with
isolated tornadoes also possible. The severe wind threat may
increase across eastern OK this evening.
DISCUSSION...Numerous 1-1.75 inch large hail reports have been
received over the past hour or two with severe storms across
central/north-central TX into southern/eastern OK. Large to very
large (1 to 3 inch) hail remains possible with the more discrete
supercells currently in north-central TX given the 3500 J/kg of
MLCAPE and steep mid-level lapse rates observed on the 00Z FWD
sounding. The low-level flow is not overly strong across this
region, but recent VWPs from KFWS show around 100-150 m2/s2 of 0-1
km SRH, which should be sufficient for low-level rotation. Indeed,
one supercell to the south of the Metroplex as of 0030Z has recently
produced a tornado. Isolated tornadoes will remain possible across
Tornado Watch 133 for at least a couple more hours, with somewhat
better potential with at least semi-discrete storms. Father north
into southern/eastern OK, storms have mostly congealed into a
cluster. All severe hazards appear possible with this activity in
the short term, but severe/damaging winds may become an increasing
concern this evening across parts of eastern OK if upscale growth
into a bow occurs along/south of a surface front.
..Gleason.. 05/04/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...TSA...FWD...OUN...
LAT...LON 31539807 32369778 33059752 33469699 34509689 35129644
35489575 35399496 34799475 34559508 32539661 31699732
31449768 31419796 31539807SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 3, 8:38 PM CDT | Mesoscale Discussion | SPC | McCurtain | 2 hr |
| May 3, 9:10 PM CDT | Severe Thunderstorm Watch | SPC | McCurtain | 7 hr |
| May 3, 11:34 PM CDT | Mesoscale Discussion | SPC | McCurtain | 86 min |
| May 4, 12:47 AM CDT | Severe Thunderstorm Watch | SPC | Atoka, Bryan, Carter, Coal, Johnston, Love and 3 more | 2 hr |
| May 4, 1:07 AM CDT | Mesoscale Discussion | SPC | Atoka, Bryan, Carter, Choctaw, Coal, Garvin and 7 more | 83 min |
| May 3, 7:01 PM CDT | Severe Thunderstorm Watch | SPC | Atascosa, Bandera, Bexar, Blanco, Burnet, Comal and 9 more | 4 hr |
| May 3, 8:30 PM CDT | Mesoscale Discussion | SPC | Bexar, Blanco, Comal, Guadalupe, Hays, Kendall | 60 min |
| May 3, 9:10 PM CDT | Mesoscale Discussion | SPC | Callahan, Eastland, Fisher, Haskell, Jones, Nolan and 6 more | 95 min |
| May 3, 9:52 PM CDT | Mesoscale Discussion | SPC | Anderson, Bell, Coryell, Ellis, Falls, Freestone and 12 more | 53 min |
| May 3, 10:22 PM CDT | Severe Thunderstorm Watch | SPC | Anderson, Bell, Collin, Cooke, Dallas, Delta and 28 more | 5 hr |
| May 4, 6:44 AM CDT | Mesoscale Discussion | SPC | Anderson, Bell, Brazos, Burleson, Camp, Cass and 23 more | 2 hr |
| May 4, 8:11 AM CDT | Severe Thunderstorm Watch | SPC | Angelina, Austin, Brazos, Burleson, Chambers, Colorado and 22 more | 8 hr |
Nearby
Mesoscale Discussions in Oklahoma, 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.