Alert archive / Texas / Mesoscale Discussions in 2021
Mesoscale Discussion 391
The Storm Prediction Center issued this mesoscale discussion at Apr 15, 2021, 4:55 PM CDT for 10 counties in Texas. It was in force for 3 hr.
The area
The outline as issued.
The facts
- Issued
- Apr 15, 2021, 4:55 PM CDT (21:55 UTC)
- Expired
- Apr 15, 2021, 7:30 PM CDT
- In force
- 3 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch possible
- Chance of a watch
- 40%
Counties Austin County, TX, Brazoria County, TX, Burleson County, TX, Fort Bend County, TX, Harris County, TX, Lee County, TX, Milam County, TX, Montgomery County, TX, Waller County, TX, Washington County, TX
The radar
The Ft Hood radar (KGRK), 121 km from the middle of the area, began a volume at 21:55 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
Corpus Christi, TX (KCRP), launched 12:00Z, 9.9 hours before the alert went out and 287 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
- 3082 J/kg
- Mixed-layer CIN
- -22 J/kg
- Mixed-layer LCL
- 497 m above ground
- 0-6 km bulk shear
- 37 kt
- 0-1 km storm-relative helicity
- 60 m²/s²
- 0-3 km storm-relative helicity
- 137 m²/s²
- Significant tornado parameter
- 1.6
- Supercell composite
- 7.8
The text
As transmitted.
795
ACUS11 KWNS 152155
SWOMCD
SPC MCD 152155
TXZ000-160030-
Mesoscale Discussion 0391
NWS Storm Prediction Center Norman OK
0455 PM CDT Thu Apr 15 2021
Areas affected...southeast Texas
Concerning...Severe potential...Watch possible
Valid 152155Z - 160030Z
Probability of Watch Issuance...40 percent
SUMMARY...A cluster of cells producing large hail may persist for a
few hours as it moves from central into southeast Texas. Watch
chances downstream will depend on storm coverage/intensity trends.
DISCUSSION...A long-lived cell just northeast of Austin TX as of
21:55Z continues to show severe hail potential. This cell is located
within the theta-e gradient just off the surface, and is utilizing
elevated instability on the order of 1500 J/kg. Given the
southeastward motion due to moderate westerlies aloft and rightward
propagation on the southern end of the cluster, this storm is in an
environment of favorable shear and storm relative inflow. While
gusty winds may also occur, damaging hail is the most likely threat.
Very little change environmentally is forecast over the next several
hours, suggesting a status-quo scenario. Flow at 850 mb may be
slightly weaker farther east.
..Jewell/Hart.. 04/15/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...HGX...FWD...EWX...
LAT...LON 31069725 30139509 29729486 29459487 29229515 29169547
30089721 30369757 30649738 30729730 31069725SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 15, 8:17 AM CDT | Mesoscale Discussion | SPC | Atascosa, Bandera, Bexar, Blanco, Comal, Edwards and 13 more | 2 hr |
| Apr 15, 8:36 AM CDT | Severe Thunderstorm Watch | SPC | Bandera, Blanco, Burnet, Concho, Crockett, Edwards and 19 more | 8 hr |
| Apr 15, 10:56 AM CDT | Mesoscale Discussion | SPC | Bandera, Concho, Edwards, Gillespie, Kerr, Kimble and 9 more | 94 min |
| Apr 15, 12:24 PM CDT | Mesoscale Discussion | SPC | Bastrop, Bell, Blanco, Burnet, Coryell, Falls and 12 more | 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.