Alert archive / Texas / Mesoscale Discussions in 2021
Mesoscale Discussion 1840
The Storm Prediction Center issued this mesoscale discussion at Oct 12, 2021, 3:14 PM CDT for 6 counties in Oklahoma; 11 counties in Texas. It was in force for 3 hr.
The area
The outline as issued.
The facts
- Issued
- Oct 12, 2021, 3:14 PM CDT (20:14 UTC)
- Expired
- Oct 12, 2021, 5:45 PM CDT
- In force
- 3 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...tornado watch likely
- Chance of a watch
- 80%
Counties Beckham County, OK, Ellis County, OK, Greer County, OK, Harmon County, OK, Jackson County, OK, Roger Mills County, OK, Childress County, TX, Collingsworth County, TX, Cottle County, TX, Donley County, TX, Foard County, TX, Gray County, TX, Hall County, TX, Hardeman County, TX, Hemphill County, TX, Roberts County, TX, Wheeler County, TX
The radar
The Altus AFB radar (KFDR), 116 km from the middle of the area, began a volume at 20:16 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, 8.2 hours before the alert went out and 154 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
- 1866 m above ground
- 0-6 km bulk shear
- 61 kt
- 0-1 km storm-relative helicity
- 399 m²/s²
- 0-3 km storm-relative helicity
- 416 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
305
ACUS11 KWNS 122014
SWOMCD
SPC MCD 122014
OKZ000-TXZ000-122245-
Mesoscale Discussion 1840
NWS Storm Prediction Center Norman OK
0314 PM CDT Tue Oct 12 2021
Areas affected...eastern Texas Panhandle into far western Oklahoma
Concerning...Severe potential...Tornado Watch likely
Valid 122014Z - 122245Z
Probability of Watch Issuance...80 percent
SUMMARY...A few supercells may develop through evening, from the
eastern Texas Panhandle into far western Oklahoma. Tornadoes,
perhaps strong, and very large hail will be possible.
DISCUSSION...Surface analysis shows a front extending from northern
TX into southwest OK which is becoming more diffuse with heating.
This boundary separates a cooler/capped air mass over much of OK
from a destabilizing air mass over northwest TX and into the TX
Panhandle. Meanwhile, a dryline stretches from north to south across
the TX Panhandle and South Plains.
Visible satellite shows stable billow clouds north of the boundary,
but these are gradually eroding from south to north as temperatures
warm into the lower 80s F. A growing CU field is also evident over
northwest TX, where MLCAPE is in the 1500-2000 J/kg range. Backed
surface winds on the cool side of the boundary are contributing to
100-150 m2/s2 0-1 km SRH per FDR VWP.
Although convergence is currently weak, it is expected to increase
around 00Z and into the evening as the dryline eventually pushes
east with the upper trough. A few more hours of air mass
modification will occur, including moistening. In addition, the
low-level jet will continue to increase to over 50 kt, further
enhancing shear.
Assuming a cell or two can form, they should quickly acquire
rotation, with tornadoes and hail likely. Any lone cells that can
maintain access to the warm side of the boundary will have the
potential for a strong tornado.
..Jewell/Grams.. 10/12/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...OUN...LUB...AMA...
LAT...LON 34959921 34639932 34139955 33929976 33760008 33720037
33790060 33930069 34480088 35050125 35580118 35960072
36389981 36319967 36279954 35749914 34959921SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Oct 12, 2:29 PM CDT | Mesoscale Discussion | SPC | Beaver, Ellis, Harper | 31 min |
| Oct 12, 3:08 PM CDT | Mesoscale Discussion | SPC | Beaver, Texas | 97 min |
| Oct 12, 5:34 PM CDT | Tornado Watch | SPC | Beaver, Beckham, Blaine, Caddo, Canadian, Comanche and 18 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.