Alert archive / Texas / Mesoscale Discussions in 2021
Mesoscale Discussion 439
The Storm Prediction Center issued this mesoscale discussion at Apr 27, 2021, 5:52 PM CDT for Comanche County, Cotton County, Tillman County, Oklahoma; 11 counties in Texas. It was in force for 113 min.
The area
The outline as issued.
The facts
- Issued
- Apr 27, 2021, 5:52 PM CDT (22:52 UTC)
- Expired
- Apr 27, 2021, 7:45 PM CDT
- In force
- 113 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe thunderstorm watch 113
Counties Comanche County, OK, Cotton County, OK, Tillman County, OK, Baylor County, TX, Dickens County, TX, Foard County, TX, Hardeman County, TX, Kent County, TX, King County, TX, Knox County, TX, Scurry County, TX, Stonewall County, TX, Wichita County, TX, Wilbarger County, TX
The radar
The Altus AFB radar (KFDR), 100 km from the middle of the area, began a volume at 22:53 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
Amarillo Airport, TX (KAMA), launched 12:00Z, 10.9 hours before the alert went out and 241 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
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 4126 m above ground
- 0-6 km bulk shear
- 53 kt
- 0-1 km storm-relative helicity
- 96 m²/s²
- 0-3 km storm-relative helicity
- 143 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
675
ACUS11 KWNS 272253
SWOMCD
SPC MCD 272252
OKZ000-TXZ000-280045-
Mesoscale Discussion 0439
NWS Storm Prediction Center Norman OK
0552 PM CDT Tue Apr 27 2021
Areas affected...Parts of the Texas South Plains into southwestern
Oklahoma
Concerning...Severe Thunderstorm Watch 113...
Valid 272252Z - 280045Z
The severe weather threat for Severe Thunderstorm Watch 113
continues.
SUMMARY...Additional supercell development is possible across the
region during the next few hours, which may pose the risk for large,
potentially damaging hail, and a tornado or two, before tending to
evolve into an increasingly organized cluster of storms during the
7-9 PM CDT time frame.
DISCUSSION...Although a subtle mid-level perturbation may now be in
the process of migrating off to the east-northeast of the region,
the primary, much more significant short wave trough is still well
upstream. As this feature continues to dig across parts of the
lower Colorado Valley/Gulf of California vicinity, it appears that
the stronger downstream difluent mid/upper flow will remain focused
across the Texas South Plains/Northwest Texas vicinity. Beneath
this regime, boundary-layer convergence and lower/mid tropospheric
warm advection remain focused along an axis northwest of Sweetwater,
TX into areas west of Wichita Falls, TX, where new thunderstorm
development appears in the process of gradually intensifying.
In the presence of thermodynamic profiles characterized by steep
lower/mid tropospheric lapse rates and CAPE on the order of
1000-2000 J/kg, at least some further erosion of mid-level
inhibition is expected to allow for rapid intensification during the
next few hours. Deep-layer and low-level shear remain supportive of
supercells, before activity tends to grow upscale and organize
through the 00-02Z time frame.
..Kerr.. 04/27/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...OUN...SJT...LUB...MAF...
LAT...LON 33390104 34140022 34699917 34869836 34609808 34219822
33619896 32920029 32660086 32840128 33390104SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 27, 1:17 PM CDT | Mesoscale Discussion | SPC | Beckham, Blaine, Caddo, Canadian, Comanche, Custer and 16 more | 118 min |
| Apr 27, 1:57 PM CDT | Severe Thunderstorm Watch | SPC | Alfalfa, Beckham, Blaine, Caddo, Canadian, Comanche and 18 more | 7 hr |
| Apr 27, 3:30 PM CDT | Mesoscale Discussion | SPC | Foard, Knox, Wilbarger | 90 min |
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.