Alert archive / Texas / Mesoscale Discussions in 2021
Mesoscale Discussion 233
The Storm Prediction Center issued this mesoscale discussion at Mar 22, 2021, 10:21 PM CDT for 58 counties in Texas. It was in force for 54 min.
The area
The outline as issued.
The facts
- Issued
- Mar 22, 2021, 10:21 PM CDT (03:21 UTC)
- Expired
- Mar 22, 2021, 11:15 PM CDT
- In force
- 54 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe thunderstorm watch 45
All 58 counties
Bandera County, TX, Bastrop County, TX, Bell County, TX, Bexar County, TX, Blanco County, TX, Bosque County, TX, Brazos County, TX, Burleson County, TX, Burnet County, TX, Caldwell County, TX, Collin County, TX, Comal County, TX, Comanche County, TX, Coryell County, TX, Dallas County, TX, Denton County, TX, Ellis County, TX, Erath County, TX, Falls County, TX, Fayette County, TX, Freestone County, TX, Gillespie County, TX, Gonzales County, TX, Grimes County, TX, Guadalupe County, TX, Hamilton County, TX, Hays County, TX, Henderson County, TX, Hill County, TX, Hood County, TX, Hunt County, TX, Johnson County, TX, Kaufman County, TX, Kendall County, TX, Kerr County, TX, Lampasas County, TX, Lee County, TX, Leon County, TX, Limestone County, TX, Llano County, TX, Madison County, TX, Mason County, TX, McLennan County, TX, Milam County, TX, Mills County, TX, Navarro County, TX, Palo Pinto County, TX, Parker County, TX, Robertson County, TX, Rockwall County, TX, San Saba County, TX, Somervell County, TX, Tarrant County, TX, Travis County, TX, Van Zandt County, TX, Washington County, TX, Williamson County, TX, Wise County, TX
The radar
The Ft Hood radar (KGRK), 45 km from the middle of the area, began a volume at 03:21 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
Fort Worth, TX (KFWD), launched 00:00Z, 3.4 hours before the alert went out and 192 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
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 679 m above ground
- 0-6 km bulk shear
- 43 kt
- 0-1 km storm-relative helicity
- 404 m²/s²
- 0-3 km storm-relative helicity
- 672 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.2
The text
As transmitted.
754
ACUS11 KWNS 230321
SWOMCD
SPC MCD 230321
TXZ000-230415-
Mesoscale Discussion 0233
NWS Storm Prediction Center Norman OK
1021 PM CDT Mon Mar 22 2021
Areas affected...central and north Texas
Concerning...Severe Thunderstorm Watch 45...
Valid 230321Z - 230415Z
The severe weather threat for Severe Thunderstorm Watch 45
continues.
SUMMARY...Recent ramp up in hail and damaging wind risk has been
noted over the past hour or so...
DISCUSSION...Convection across WW 45 appears to be responding well
to increased low-level shear (associated with strengthening of 850mb
flow across the region) and destabilization aloft with steep
mid-level lapse rates overspreading the moist boundary layer
(characterized by near 60F dewpoints). A couple of fairly
impressive supercell structures have been noted west/northwest of
Austin and hail reports as large as 2.5 inch in diameter have also
been noted. Linear segments nearer the DFW area have also resulted
in a recent 46 knot wind gusts near Rockwall, Texas.
Latest high-resolution guidance is most aggressive with longevity of
ongoing convection from near ACT to 50 NW SAT. These storms should
migrate east-southeastward and continue to pose a risk of hail/wind
over the next couple hours while approaching the eastern extent of
WW 45. Trends will be monitored for the possibility of either local
extensions of WW 45 in space and time or a new Severe Thunderstorm
Watch for downstream areas.
..Cook/Guyer.. 03/23/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...HGX...FWD...EWX...SJT...
LAT...LON 29529711 29399767 29379891 29599963 30309951 31499894
32289867 33009829 33379728 33369629 32999583 31799577
30729572 29999614 29529711SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Mar 22, 8:25 PM CDT | Mesoscale Discussion | SPC | Archer, Baylor, Bell, Blanco, Bosque, Brown and 53 more | 65 min |
| Mar 22, 10:44 PM CDT | Mesoscale Discussion | SPC | Delta, Fannin, Franklin, Hopkins, Hunt, Kaufman and 6 more | 61 min |
| Mar 22, 11:10 PM CDT | Severe Thunderstorm Watch | SPC | Austin, Bandera, Bastrop, Bexar, Blanco, Brazos and 29 more | 5 hr |
| Mar 23, 1:29 AM CDT | Mesoscale Discussion | SPC | Atascosa, Austin, Bandera, Bastrop, Bexar, Brazos and 29 more | 91 min |
| Mar 23, 3:19 AM CDT | Mesoscale Discussion | SPC | Angelina, Austin, Colorado, DeWitt, Fayette, Fort Bend and 20 more | 56 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.