Alert archive / Texas / Mesoscale Discussions in 2021
Mesoscale Discussion 505
The Storm Prediction Center issued this mesoscale discussion at May 3, 2021, 5:55 PM CDT for 6 counties in Oklahoma; 7 counties in Texas. It was in force for 95 min.
The area
The outline as issued.
The facts
- Issued
- May 3, 2021, 5:55 PM CDT (22:55 UTC)
- Expired
- May 3, 2021, 7:30 PM CDT
- In force
- 95 min
- Issued by
- the Storm Prediction Center
- Concerning
- Tornado watch 133
Counties Coal County, OK, Johnston County, OK, Love County, OK, Marshall County, OK, Murray County, OK, Pontotoc County, OK, Bosque County, TX, Cooke County, TX, Denton County, TX, Grayson County, TX, Johnson County, TX, Somervell County, TX, Tarrant County, TX
The radar
The Dallas/Ft Worth radar (KFWS), 60 km from the middle of the area, began a volume at 22:58 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 12:00Z, 10.9 hours before the alert went out and 32 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
- 1296 J/kg
- Mixed-layer CIN
- -475 J/kg
- Mixed-layer LCL
- 1712 m above ground
- 0-6 km bulk shear
- 29 kt
- 0-1 km storm-relative helicity
- 480 m²/s²
- 0-3 km storm-relative helicity
- 456 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
568
ACUS11 KWNS 032255
SWOMCD
SPC MCD 032255
OKZ000-TXZ000-040030-
Mesoscale Discussion 0505
NWS Storm Prediction Center Norman OK
0555 PM CDT Mon May 03 2021
Areas affected...Portions of north-central TX into southern OK
Concerning...Tornado Watch 133...
Valid 032255Z - 040030Z
The severe weather threat for Tornado Watch 133 continues.
SUMMARY...The threat for large to very large hail should become
maximized in the next couple of hours. Some of the very large hail
could be 2-3+ inches in diameter. The tornado threat may gradually
increase early this evening with any storms that remain discrete.
DISCUSSION...Convection has erupted over the past hour or two along
a composite cold front/dryline. Numerous instances of 1-1.75 inch
hail have been reported with this activity. The airmass downstream
of these severe storms remains strongly unstable, with MLCAPE of
2500-4000 J/kg present. There have been some storm mergers and
interactions along the surface boundary so far, and if this trends
continues it could limit the very large hail threat to some extent.
Still, given the presence of very steep mid-level lapse rates (8.6
C/km in the 700-500 mb layer) per the 19Z observed sounding from FWD
and enhanced flow at mid/upper levels, any supercell that can turn
right and move off the boundary will have the potential to produce
2-3+ inch hail over the next couple of hours. Otherwise, the tornado
threat may gradually increase through the early evening with any
cell that can remain discrete, even though the low-level flow is not
forecast to become overly strong.
..Gleason.. 05/03/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...FWD...OUN...
LAT...LON 31869791 32709764 33749742 34529714 34929665 34839616
33729647 32629688 31779731 31649778 31869791SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 3, 3:14 PM CDT | Mesoscale Discussion | SPC | Atoka, Bryan, Carter, Choctaw, Coal, Garvin and 10 more | 2 hr |
| May 3, 3:48 PM CDT | Tornado Watch | SPC | Adair, Atoka, Bryan, Carter, Cherokee, Choctaw and 18 more | 7 hr |
| May 3, 12:44 PM CDT | Mesoscale Discussion | SPC | Dallam, Deaf Smith, Hartley, Moore, Oldham | 2 hr |
| May 3, 2:24 PM CDT | Mesoscale Discussion | SPC | Andrews, Borden, Cochran, Dawson, Fisher, Gaines and 12 more | 2 hr |
| May 3, 3:15 PM CDT | Severe Thunderstorm Watch | SPC | Andrews, Borden, Cochran, Crosby, Dawson, Gaines and 12 more | 6 hr |
| May 3, 5:12 PM CDT | Mesoscale Discussion | SPC | Borden, Cochran, Dawson, Gaines, Garza, Lynn and 3 more | 93 min |
| May 3, 5:56 PM CDT | Mesoscale Discussion | SPC | Frio, La Salle, Medina | 94 min |
| May 3, 6:19 PM CDT | Mesoscale Discussion | SPC | Callahan, Eastland, Fisher, Haskell, Jack, Jones and 8 more | 116 min |
| May 3, 6:36 PM CDT | Severe Thunderstorm Watch | SPC | Callahan, Eastland, Fisher, Haskell, Jack, Jones and 8 more | 5 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.