Alert archive / Oklahoma / Mesoscale Discussions in 2021
Mesoscale Discussion 1842
The Storm Prediction Center issued this mesoscale discussion at Oct 12, 2021, 7:30 PM CDT for 16 counties in Oklahoma; 9 counties in Texas. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Oct 12, 2021, 7:30 PM CDT (00:30 UTC)
- Expired
- Oct 12, 2021, 9:30 PM CDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Tornado watch 523
All 25 counties
Beaver County, OK, Beckham County, OK, Caddo County, OK, Comanche County, OK, Cotton County, OK, Custer County, OK, Dewey County, OK, Ellis County, OK, Greer County, OK, Harmon County, OK, Jackson County, OK, Kiowa County, OK, Roger Mills County, OK, Tillman County, OK, Washita County, OK, Woodward County, OK, Collingsworth County, TX, Gray County, TX, Hansford County, TX, Hemphill County, TX, Lipscomb County, TX, Ochiltree County, TX, Roberts County, TX, Wheeler County, TX, Wilbarger County, TX
The radar
The Altus AFB radar (KFDR), 125 km from the middle of the area, began a volume at 00:32 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 00:00Z, 0.5 hours before the alert went out and 184 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
- 165 J/kg
- Mixed-layer CIN
- -69 J/kg
- Mixed-layer LCL
- 2910 m above ground
- 0-6 km bulk shear
- 49 kt
- 0-1 km storm-relative helicity
- 141 m²/s²
- 0-3 km storm-relative helicity
- 172 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.7
The text
As transmitted.
288
ACUS11 KWNS 130031
SWOMCD
SPC MCD 130030
OKZ000-TXZ000-KSZ000-130230-
Mesoscale Discussion 1842
NWS Storm Prediction Center Norman OK
0730 PM CDT Tue Oct 12 2021
Areas affected...Eastern Texas Panhandle and Western Oklahoma
Concerning...Tornado Watch 523...
Valid 130030Z - 130230Z
The severe weather threat for Tornado Watch 523 continues.
SUMMARY...The severe weather threat continues across WW 523. The
greatest near-term threat will remain across western OK associated
with isolated supercells, but a second round of storms remains
likely later this evening.
DISCUSSION...Latest regional radar imagery shows a few supercells
moving north/northeastward across far north Texas and western
Oklahoma. The west-central OK supercell has exhibited strong
low-level rotation, indicating that the ample low-level shear over
the region (200-300 m2/s2 0-1 km SRH sampled by the KFDR VWP and
analyzed in recent RAP mesoanalysis) is compensating for lingering
mixed-layer inhibition. The tornado threat associated with this
storm will continue for the near term, and may persist into the late
evening hours as low-level wind fields strengthen in response to the
deepening surface low to the north.
Additional discrete cells are possible across southwest OK and/or
the eastern TX Panhandle along the warm front within the next 1-2
hours, but weak forcing for ascent, substantial mid-level dry air
entrainment, and the onset of diurnal cooling make confidence in
discrete storm coverage uncertain. Latest hi-res guidance has
depicted this potential, but run-to-run consistency has been
somewhat poor, further reducing confidence.
Additional storms are likely later this evening/overnight as
stronger lift associated with the approach of the main upper-level
wave (manifesting as increasing showers and weak convection over the
southern High Plains) overspreads the region. Increasingly
meridional flow along the initiating cold front will support mostly
linear storm modes, but increasing low-level shear within the warm
sector should maintain a QLCS tornado threat over the watch area.
..Moore.. 10/13/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...OUN...DDC...LUB...AMA...
LAT...LON 34500004 34920063 35460117 36180145 36790146 37010086
36829988 36679951 36149884 35329834 34639813 34259816
34069842 34029859 34039936 34500004SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Oct 12, 9:18 PM CDT | Mesoscale Discussion | SPC | Beaver, Beckham, Blaine, Caddo, Canadian, Comanche and 12 more | 117 min |
| Oct 12, 11:05 PM CDT | Tornado Watch | SPC | Alfalfa, Beaver, Beckham, Blaine, Caddo, Canadian and 19 more | 7 hr |
| Oct 13, 1:18 AM CDT | Mesoscale Discussion | SPC | Alfalfa, Beckham, Blaine, Custer, Dewey, Ellis and 7 more | 87 min |
| Oct 13, 3:26 AM CDT | Mesoscale Discussion | SPC | Blaine, Caddo, Canadian, Garfield, Grant, Jackson and 6 more | 94 min |
| Oct 13, 5:16 AM CDT | Mesoscale Discussion | SPC | Cleveland, Creek, Grady, Lincoln, Logan, McClain and 9 more | 59 min |
| Oct 13, 7:34 AM CDT | Mesoscale Discussion | SPC | Cherokee, Craig, Delaware, Hughes, McIntosh, Mayes and 9 more | 116 min |
| Oct 13, 3:59 PM CDT | Mesoscale Discussion | SPC | Brown, Coleman, Collin, Comanche, Cooke, Denton and 9 more | 91 min |
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.