Alert archive / Texas / Mesoscale Discussions in 2021
Mesoscale Discussion 469
The Storm Prediction Center issued this mesoscale discussion at May 1, 2021, 8:06 AM CDT for 12 counties in Texas. It was in force for 114 min.
The area
The outline as issued.
The facts
- Issued
- May 1, 2021, 8:06 AM CDT (13:06 UTC)
- Expired
- May 1, 2021, 10:00 AM CDT
- In force
- 114 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 20%
Counties Atascosa County, TX, Bexar County, TX, Dimmit County, TX, Frio County, TX, Kinney County, TX, La Salle County, TX, Maverick County, TX, McMullen County, TX, Medina County, TX, Uvalde County, TX, Wilson County, TX, Zavala County, TX
The radar
The Laughlin AFB radar (KDFX), 88 km from the middle of the area, began a volume at 13:11 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
Del Rio, TX (KDRT), launched 12:00Z, 1.1 hours before the alert went out and 142 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
- 155 J/kg
- Mixed-layer CIN
- -34 J/kg
- Mixed-layer LCL
- 538 m above ground
- 0-6 km bulk shear
- 37 kt
- 0-1 km storm-relative helicity
- -31 m²/s²
- 0-3 km storm-relative helicity
- -5 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
031
ACUS11 KWNS 011307
SWOMCD
SPC MCD 011306
TXZ000-011500-
Mesoscale Discussion 0469
NWS Storm Prediction Center Norman OK
0806 AM CDT Sat May 01 2021
Areas affected...Rio Grande Valley eastward into southern Texas
Concerning...Severe potential...Watch unlikely
Valid 011306Z - 011500Z
Probability of Watch Issuance...20 percent
SUMMARY...Storms crossing the Rio Grande may produce marginal hail
this morning, but a watch is unlikely.
DISCUSSION...Storms have increased in intensity and coverage over
northern Coahuila, with marginal MESH shown on radar. These storms
are in a rather weakly unstable air mass with only a few hundred
J/kg of MUCAPE, but are aided by cooling aloft with the upper low.
The 12Z DRT sounding shows little instability, but modifying for
observed temperatures and dewpoints to the southeast yields
sufficient instability.
Ample PWAT exists over southern TX (1.50-1.75" per GPS sensors), but
little heating is expected in the near term. However, easterly mean
winds in the low levels will aid storm-relative inflow to any
approaching cells, and may maximize updrafts despite marginal
instability. Cold temperatures aloft could support hail.
Storm evolution will continue to be monitored this morning as
conditions ahead of these storms destabilize further.
..Jewell/Edwards.. 05/01/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...CRP...EWX...
LAT...LON 29280108 29720032 29799960 29689869 29529832 29199805
28749797 28319823 27989889 27739956 27889997 28320034
28930077 29280108SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 1, 11:08 AM CDT | Mesoscale Discussion | SPC | Bexar, Medina | 97 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.