Alert archive / Texas / Mesoscale Discussions in 2021
Mesoscale Discussion 245
The Storm Prediction Center issued this mesoscale discussion at Mar 24, 2021, 8:15 PM CDT for 35 counties in Texas. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Mar 24, 2021, 8:15 PM CDT (01:15 UTC)
- Expired
- Mar 24, 2021, 10:15 PM CDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch likely
- Chance of a watch
- 95%
All 35 counties
Bandera County, TX, Bell County, TX, Blanco County, TX, Bosque County, TX, Brown County, TX, Burnet County, TX, Comanche County, TX, Concho County, TX, Coryell County, TX, Edwards County, TX, Erath County, TX, Falls County, TX, Gillespie County, TX, Hamilton County, TX, Hays County, TX, Hill County, TX, Kendall County, TX, Kerr County, TX, Kimble County, TX, Kinney County, TX, Lampasas County, TX, Llano County, TX, Mason County, TX, McCulloch County, TX, McLennan County, TX, Medina County, TX, Menard County, TX, Mills County, TX, Real County, TX, San Saba County, TX, Somervell County, TX, Sutton County, TX, Uvalde County, TX, Val Verde County, TX, Williamson County, TX
The radar
The Austin/San Antonio radar (KEWX), 145 km from the middle of the area, began a volume at 01:16 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
Del Rio, TX (KDRT), launched 00:00Z, 1.3 hours before the alert went out and 223 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
- 479 J/kg
- Mixed-layer CIN
- -29 J/kg
- Mixed-layer LCL
- 2767 m above ground
- 0-6 km bulk shear
- 80 kt
- 0-1 km storm-relative helicity
- 13 m²/s²
- 0-3 km storm-relative helicity
- 317 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 1.9
The text
As transmitted.
101
ACUS11 KWNS 250115
SWOMCD
SPC MCD 250115
TXZ000-250315-
Mesoscale Discussion 0245
NWS Storm Prediction Center Norman OK
0815 PM CDT Wed Mar 24 2021
Areas affected...Edwards Plateau into the TX Hill Country
Concerning...Severe potential...Watch likely
Valid 250115Z - 250315Z
Probability of Watch Issuance...95 percent
SUMMARY...Additional storm development is likely by mid to late
evening. All severe hazards (hail, wind, tornado) are possible. A
new watch will likely need to be coordinated before 10pm prior to
expiration of tornado watch #47. The type of watch (severe
thunderstorm, tornado) is still a bit uncertain.
DISCUSSION...Visible/IR satellite imagery during the past 1.5 hours
has shown the development of a mid-level cloud patch straddling the
Rio Grande from parts of Terrell and Val Verde counties. The cloud
development is likely in response to stronger forcing for ascent
beginning to spread east towards the west edge of the moist/unstable
sector located over the TX Hill Country. As the upward vertical
motion continues to move east, concurrent with a strengthening
low-level jet, expecting the gradual development of additional
thunderstorms initially near Val Verde, Sutton, and Edwards
counties. As this activity matures, an accompanying severe risk is
probable given strong vertical shear and ample instability. Large
hail and severe gusts appear to be the primary risk. However, some
recent CAM model runs have shown the development of strong simulated
supercells. Although the low-level shear is not currently forecast
to be very strong, a conditional risk for a few low-level
mesocyclones and an attendant tornado risk could materialize.
Nonetheless, vigorous storms capable of hail/wind will likely
develop and a severe risk will probably linger into the overnight.
..Smith/Grams.. 03/25/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...FWD...EWX...SJT...
LAT...LON 29540128 30270114 31649975 32339866 32349769 31949674
31489667 30929690 29659853 29129943 29110066 29540128SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Mar 24, 7:37 PM CDT | Mesoscale Discussion | SPC | Bowie, Camp, Cass, Collin, Cooke, Dallas and 23 more | 53 min |
| Mar 24, 9:52 PM CDT | Tornado Watch | SPC | Bandera, Bell, Bexar, Blanco, Bosque, Burnet and 37 more | 6 hr |
| Mar 24, 10:28 PM CDT | Mesoscale Discussion | SPC | Edwards, Kimble | 62 min |
| Mar 24, 11:37 PM CDT | Mesoscale Discussion | SPC | Bowie, Cass, Lamar, Morris, Red River, Titus | 53 min |
| Mar 24, 11:42 PM CDT | Mesoscale Discussion | SPC | Burnet, Coryell, Lampasas, Llano, Mason, San Saba | 93 min |
| Mar 25, 1:40 AM CDT | Mesoscale Discussion | SPC | Anderson, Bandera, Bell, Bexar, Blanco, Bosque and 40 more | 95 min |
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.