Alert archive / Texas / Mesoscale Discussions in 2021
Mesoscale Discussion 346
The Storm Prediction Center issued this mesoscale discussion at Apr 9, 2021, 3:59 PM CDT for 20 counties in Texas. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Apr 9, 2021, 3:59 PM CDT (20:59 UTC)
- Expired
- Apr 9, 2021, 6:00 PM CDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch possible
- Chance of a watch
- 40%
Counties Bastrop County, TX, Bell County, TX, Blanco County, TX, Bosque County, TX, Burnet County, TX, Caldwell County, TX, Comal County, TX, Coryell County, TX, Falls County, TX, Guadalupe County, TX, Hays County, TX, Hill County, TX, Hood County, TX, Johnson County, TX, Kendall County, TX, McLennan County, TX, Milam County, TX, Somervell County, TX, Travis County, TX, Williamson County, TX
The radar
The Ft Hood radar (KGRK), 47 km from the middle of the area, began a volume at 21:01 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
Fort Worth, TX (KFWD), launched 12:00Z, 9.0 hours before the alert went out and 224 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
- 1461 J/kg
- Mixed-layer CIN
- -451 J/kg
- Mixed-layer LCL
- 890 m above ground
- 0-6 km bulk shear
- 30 kt
- 0-1 km storm-relative helicity
- 401 m²/s²
- 0-3 km storm-relative helicity
- 399 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- -0.2
The text
As transmitted.
345
ACUS11 KWNS 092100
SWOMCD
SPC MCD 092059
TXZ000-092300-
Mesoscale Discussion 0346
NWS Storm Prediction Center Norman OK
0359 PM CDT Fri Apr 09 2021
Areas affected...Parts of central Texas
Concerning...Severe potential...Watch possible
Valid 092059Z - 092300Z
Probability of Watch Issuance...40 percent
SUMMARY...Isolated to widely scattered intense thunderstorms
increasingly possible through 5-6 PM, accompanied by the risk for
large, potentially damaging, hail and locally strong surface gusts.
A severe weather watch may be needed within the next hour or so.
DISCUSSION...The deepening moist boundary layer has become strongly
unstable along/east of the dryline which is still just west of the
Interstate 35 corridor, across north central through central Texas.
As mid-level troughing begins to overspread this region, it appears
that cooling aloft is contributing to weakening of initially strong
mid-level inhibition. Initial attempts at thunderstorm development
may be underway to the west of the dryline, based on recent
satellite imagery, and isolated to widely scattered thunderstorm
development appears possible through 22-23Z.
Strongest deep-layer shear, beneath the high-level jet of
lower-latitude Pacific origin, is generally south of the Dallas-Fort
Worth Metroplex, between Waco and San Antonio, where potential for
supercells currently seems highest. This probably will be
accompanied by a risk for large, potentially damaging hail, and
locally strong surface gusts into early evening.
..Kerr/Thompson.. 04/09/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...HGX...FWD...EWX...
LAT...LON 32539781 32609689 30859676 29859735 29379815 29539867
29889878 30729831 32539781SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 8, 9:58 PM CDT | Mesoscale Discussion | SPC | Anderson, Brazos, Cherokee, Freestone, Grimes, Henderson and 7 more | 2 hr |
| Apr 9, 9:49 AM CDT | Mesoscale Discussion | SPC | Bowie, Camp, Cass, Collin, Cooke, Delta and 20 more | 116 min |
| Apr 9, 12:07 PM CDT | Severe Thunderstorm Watch | SPC | Bowie, Camp, Cass, Gregg, Harrison, Marion and 5 more | 6 hr |
| Apr 9, 1:25 PM CDT | Mesoscale Discussion | SPC | Cherokee, Nacogdoches, Panola, Rusk, San Augustine, Shelby | 95 min |
| Apr 9, 3:14 PM CDT | Mesoscale Discussion | SPC | Cooke, Delta, Fannin, Grayson, Lamar, Montague and 1 more | 61 min |
| Apr 9, 4:27 PM CDT | Severe Thunderstorm Watch | SPC | Anderson, Bell, Bosque, Collin, Cooke, Coryell and 26 more | 9 hr |
| Apr 9, 5:19 PM CDT | Mesoscale Discussion | SPC | Angelina, Cherokee, Nacogdoches, Sabine, San Augustine, Shelby | 116 min |
| Apr 9, 5:32 PM CDT | Severe Thunderstorm Watch | SPC | Angelina, Brazos, Burleson, Cherokee, Gregg, Grimes and 16 more | 7 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.