Alert archive / Texas / Mesoscale Discussions in 2021
Mesoscale Discussion 506
The Storm Prediction Center issued this mesoscale discussion at May 3, 2021, 5:56 PM CDT for Frio County, La Salle County, Medina County, Texas. It was in force for 94 min.
The area
The outline as issued.
The facts
- Issued
- May 3, 2021, 5:56 PM CDT (22:56 UTC)
- Expired
- May 3, 2021, 7:30 PM CDT
- In force
- 94 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 20%
Counties Frio County, TX, La Salle County, TX, Medina County, TX
The radar
The Laughlin AFB radar (KDFX), 130 km from the middle of the area, began a volume at 23:01 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 12:00Z, 10.9 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
- 32 J/kg
- Mixed-layer CIN
- -642 J/kg
- Mixed-layer LCL
- 2302 m above ground
- 0-6 km bulk shear
- 47 kt
- 0-1 km storm-relative helicity
- 219 m²/s²
- 0-3 km storm-relative helicity
- 227 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
445
ACUS11 KWNS 032256
SWOMCD
SPC MCD 032256
TXZ000-040030-
Mesoscale Discussion 0506
NWS Storm Prediction Center Norman OK
0556 PM CDT Mon May 03 2021
Areas affected...South central TX
Concerning...Severe potential...Watch unlikely
Valid 032256Z - 040030Z
Probability of Watch Issuance...20 percent
SUMMARY...Isolated thunderstorm development possible through about
7pm CDT, but uncertainty remains high. If storms form, the storm
environment conditionally favors supercells capable of producing
large hail and damaging winds.
DISCUSSION...Towering cumulus and a couple of orphan anvils have
been noted from 2230-2250z in visible imagery from La Salle
northward into Medina County in south central TX. These updrafts
are forming along a weak surface trough/pseudo dryline that should
retreat slowly westward this evening. Given the very hot surface
temperatures and deep mixing layer along and west of the trough,
there will be at least a low chance of sustained storm development
before the boundary layer begins to stabilize near and after 00z.
If sustained updrafts can initiate in this zone, the storm
environment is conditionally favorable for supercells given large
CAPE, steep lapse rates, and strong deep-layer vertical shear.
While a watch is not currently expected given the uncertainty in
sustained storm development, this area will be monitored for a
conditional large hail/damaging wind threat for a few hours this
evening.
..Thompson.. 05/03/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...CRP...EWX...
LAT...LON 28709894 28209898 28009910 28069928 28639932 29169927
29469910 29499891 29309893 28709894SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 3, 12:44 PM CDT | Mesoscale Discussion | SPC | Dallam, Deaf Smith, Hartley, Moore, Oldham | 2 hr |
| May 3, 2:24 PM CDT | Mesoscale Discussion | SPC | Andrews, Borden, Cochran, Dawson, Fisher, Gaines and 12 more | 2 hr |
| May 3, 3:14 PM CDT | Mesoscale Discussion | SPC | Bosque, Collin, Comanche, Cooke, Dallas, Delta and 24 more | 2 hr |
| May 3, 3:15 PM CDT | Severe Thunderstorm Watch | SPC | Andrews, Borden, Cochran, Crosby, Dawson, Gaines and 12 more | 6 hr |
| May 3, 3:48 PM CDT | Tornado Watch | SPC | Bell, Bosque, Collin, Comanche, Cooke, Coryell and 27 more | 7 hr |
| May 3, 5:12 PM CDT | Mesoscale Discussion | SPC | Borden, Cochran, Dawson, Gaines, Garza, Lynn and 3 more | 93 min |
| May 3, 5:55 PM CDT | Mesoscale Discussion | SPC | Bosque, Cooke, Denton, Grayson, Johnson, Somervell and 1 more | 95 min |
| May 3, 6:19 PM CDT | Mesoscale Discussion | SPC | Callahan, Eastland, Fisher, Haskell, Jack, Jones and 8 more | 116 min |
| May 3, 6:36 PM CDT | Severe Thunderstorm Watch | SPC | Callahan, Eastland, Fisher, Haskell, Jack, Jones and 8 more | 5 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.