Alert archive / Texas / Mesoscale Discussions in 2021
Mesoscale Discussion 470
The Storm Prediction Center issued this mesoscale discussion at May 1, 2021, 11:08 AM CDT for Bexar County, Medina County, Texas. It was in force for 97 min.
The area
The outline as issued.
The facts
- Issued
- May 1, 2021, 11:08 AM CDT (16:08 UTC)
- Expired
- May 1, 2021, 12:45 PM CDT
- In force
- 97 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 20%
Counties Bexar County, TX, Medina County, TX
The radar
The Austin/San Antonio radar (KEWX), 89 km from the middle of the area, began a volume at 16:07 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, 4.1 hours before the alert went out and 203 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.
660
ACUS11 KWNS 011608
SWOMCD
SPC MCD 011608
TXZ000-011745-
Mesoscale Discussion 0470
NWS Storm Prediction Center Norman OK
1108 AM CDT Sat May 01 2021
Areas affected...south central Texas
Concerning...Severe potential...Watch unlikely
Valid 011608Z - 011745Z
Probability of Watch Issuance...20 percent
SUMMARY...Thunderstorms could pose a risk for locally strong, but
probably sub-severe wind gusts as they continue northeast through
South Central Texas through 18Z. At this time a ww will probably not
be needed, but trends will continue to be monitored.
DISCUSSION...A forced line of storms has recently become better
organized just southwest of San Antonio and is moving northeast at
near 30 kt. This band of storms is developing in association with a
northward-moving MCV. Downstream the atmosphere is only marginally
unstable with around 500 J/kg MUCAPE and weak lapse rates. VWP data
show easterly flow through the lowest 2 km which, given the weak
cap, should augment deep convergence along the leading gust front
and help to maintain forward propagation next couple hours. The
widespread low clouds will significantly limit degree of boundary
layer destabilization in the near term, which combined with only
modest mid-level flow and weak lapse rates should limit overall
severe threat. Nevertheless, a few instances of strong wind gusts
cannot be ruled out as this activity continues northeast next couple
hours.
..Dial/Grams.. 05/01/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...EWX...
LAT...LON 28799894 29139908 29449914 29749861 29559814 29039843
28799894SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 1, 8:06 AM CDT | Mesoscale Discussion | SPC | Atascosa, Bexar, Dimmit, Frio, Kinney, La Salle and 6 more | 114 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.