Alert archive / Texas / Mesoscale Discussions in 2021
Mesoscale Discussion 645
The Storm Prediction Center issued this mesoscale discussion at May 16, 2021, 8:54 PM CDT for 7 counties in Texas. It was in force for 96 min.
The area
The outline as issued.
The facts
- Issued
- May 16, 2021, 8:54 PM CDT (01:54 UTC)
- Expired
- May 16, 2021, 10:30 PM CDT
- In force
- 96 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe thunderstorm watch 177...179
Counties Briscoe County, TX, Cottle County, TX, Foard County, TX, Hall County, TX, King County, TX, Knox County, TX, Motley County, TX
The radar
The Altus AFB radar (KFDR), 135 km from the middle of the area, began a volume at 01:55 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 watches that followed
Watches SPC issued over any of the same counties within four hours of this discussion.
The nearest sounding before it
Amarillo Airport, TX (KAMA), launched 00:00Z, 1.9 hours before the alert went out and 155 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
- 449 J/kg
- Mixed-layer CIN
- -105 J/kg
- Mixed-layer LCL
- 2191 m above ground
- 0-6 km bulk shear
- 36 kt
- 0-1 km storm-relative helicity
- 98 m²/s²
- 0-3 km storm-relative helicity
- 250 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 2.5
The text
As transmitted.
955
ACUS11 KWNS 170155
SWOMCD
SPC MCD 170154
TXZ000-170330-
Mesoscale Discussion 0645
NWS Storm Prediction Center Norman OK
0854 PM CDT Sun May 16 2021
Areas affected...Southern Texas Panhandle through northwest Texas
Concerning...Severe Thunderstorm Watch 177...179...
Valid 170154Z - 170330Z
The severe weather threat for Severe Thunderstorm Watch 177, 179
continues.
SUMMARY...Storms will continue to pose a risk for damaging wind and
large hail especially across the southeast part of the TX Panhandle
into northwest TX through 04Z. Trends will be monitored for a
possible WW downstream across northwest TX.
DISCUSSION...As of mid evening storms over the southeast TX
Panhandle have become better organized and evolved into a bowing
linear structure as it accelerates southeast. The downstream
atmosphere remains moderately unstable and a strengthening southerly
low-level jet should support a forward propagating line next couple
hours. However, visible imagery just prior to sunset showed a
westward surging outflow boundary across northwest TX. This along
with onset of nocturnal cooling increases uncertainty regarding how
storms will evolve as they move into northwest TX. It is possible
storms may intensify further as they interact with the convective
outflow boundary, but weaken soon after. Given the mesoscale
uncertainties, any additional WW issuance downstream of WW 177 / 179
will depend on convective trends during the next hour or two.
..Dial.. 05/17/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...OUN...LUB...AMA...
LAT...LON 34830071 34249975 34009929 33429953 33650077 34460159
34870124 34830071SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 16, 7:08 PM CDT | Severe Thunderstorm Watch | SPC | Cottle, Crosby, Dickens, Floyd, Garza, Hale and 8 more | 6 hr |
| May 16, 9:38 PM CDT | Severe Thunderstorm Watch | SPC | Archer, Baylor, Clay, Foard, Hardeman, Haskell and 10 more | 4 hr |
| May 16, 10:46 PM CDT | Mesoscale Discussion | SPC | Baylor, Cottle, Dickens, Foard, Haskell, King and 3 more | 59 min |
| May 17, 1:09 AM CDT | Mesoscale Discussion | SPC | Archer, Baylor, Clay, Crosby, Dickens, Fisher and 17 more | 96 min |
| May 17, 9:18 AM CDT | Mesoscale Discussion | SPC | Jasper, Jefferson, Newton, Orange | 117 min |
| May 17, 12:47 PM CDT | Mesoscale Discussion | SPC | Austin, Bastrop, Bell, Blanco, Brazoria, Brazos and 29 more | 88 min |
| May 17, 1:39 PM CDT | Mesoscale Discussion | SPC | Dallam, Hartley, Oldham | 2 hr |
| May 17, 2:11 PM CDT | Mesoscale Discussion | SPC | Andrews, Bailey, Borden, Castro, Cochran, Crane and 20 more | 2 hr |
| May 17, 2:39 PM CDT | Severe Thunderstorm Watch | SPC | Armstrong, Carson, Collingsworth, Dallam, Donley, Gray and 10 more | 8 hr |
| May 17, 3:04 PM CDT | Tornado Watch | SPC | Andrews, Bailey, Borden, Briscoe, Castro, Cochran and 39 more | 8 hr |
| May 17, 4:44 PM CDT | Tornado Watch | SPC | Baylor, Childress, Cottle, Fisher, Foard, Hardeman and 10 more | 6 hr |
| May 17, 4:53 PM CDT | Mesoscale Discussion | SPC | Baylor, Callahan, Childress, Cottle, Fisher, Foard and 11 more | 97 min |
| May 17, 5:10 PM CDT | Mesoscale Discussion | SPC | Dallam, Hansford, Hartley, Hutchinson, Moore, Ochiltree and 3 more | 2 hr |
| May 17, 5:36 PM CDT | Mesoscale Discussion | SPC | Andrews, Armstrong, Bailey, Borden, Briscoe, Castro and 38 more | 84 min |
| May 17, 6:13 PM CDT | Mesoscale Discussion | SPC | Dimmit, La Salle, Webb | 92 min |
| May 17, 6:40 PM CDT | Severe Thunderstorm Watch | SPC | Dimmit, Frio, La Salle, Maverick, Webb, Zavala | 4 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.