Alert archive / Texas / Mesoscale Discussions in 2021
Mesoscale Discussion 1791
The Storm Prediction Center issued this mesoscale discussion at Sep 29, 2021, 3:13 PM CDT for 11 counties in Texas. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Sep 29, 2021, 3:13 PM CDT (20:13 UTC)
- Expired
- Sep 29, 2021, 5:15 PM CDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 5%
Counties Archer County, TX, Brown County, TX, Callahan County, TX, Clay County, TX, Coleman County, TX, Eastland County, TX, Jack County, TX, McCulloch County, TX, Palo Pinto County, TX, Stephens County, TX, Young County, TX
The radar
The Dyess AFB radar (KDYX), 24 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 nearest sounding before it
Fort Worth, TX (KFWD), launched 12:00Z, 8.2 hours before the alert went out and 169 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
- 5 J/kg
- Mixed-layer CIN
- -407 J/kg
- Mixed-layer LCL
- 1372 m above ground
- 0-6 km bulk shear
- 11 kt
- 0-1 km storm-relative helicity
- -33 m²/s²
- 0-3 km storm-relative helicity
- 147 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
766
ACUS11 KWNS 292014
SWOMCD
SPC MCD 292013
TXZ000-292215-
Mesoscale Discussion 1791
NWS Storm Prediction Center Norman OK
0313 PM CDT Wed Sep 29 2021
Areas affected...Parts of northwest Texas into the Edwards Plateau
Concerning...Severe potential...Watch unlikely
Valid 292013Z - 292215Z
Probability of Watch Issuance...5 percent
SUMMARY...A few storms capable of producing marginally severe hail
and locally strong wind gusts are possible into the 5-7 PM CDT time
frame.
DISCUSSION...With strong daytime heating and deep boundary-layer
mixing to its west, the dryline has sharpened, roughly west of
Wichita Falls southward toward Junction. Mixed-layer CAPE is
maximizing (on the order of 2000 J/kg) in a narrow corridor along
and to its east, with the initiation of scattered thunderstorm
development ongoing, ahead of weak lower/mid tropospheric troughing.
Deep-layer mean flow and shear are generally weak, but veering with
height might still be sufficient to support occasional isolated
supercell structures with the potential to produce severe hail.
Sustained storms may tend to slowly advect east of the dryline, but
they are expected to weaken with inflow of less unstable air.
However, the dryline probably will remain the focus for renewed
vigorous thunderstorm development into early evening, before the
boundary-layer stabilizes with the loss of daytime heating.
..Kerr/Thompson.. 09/29/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...FWD...OUN...SJT...
LAT...LON 31669958 32229950 33079891 33959883 33989816 33099785
31139912 31189973 31669958SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 28, 7:01 PM CDT | Mesoscale Discussion | SPC | Atascosa, Bandera, Bee, Bexar, DeWitt, Dimmit and 14 more | 89 min |
| Sep 29, 2:06 AM CDT | Mesoscale Discussion | SPC | Calhoun, Victoria | 2 hr |
Nearby
Mesoscale 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.