Alert archive / Texas / Mesoscale Discussions in 2021
Mesoscale Discussion 681
The Storm Prediction Center issued this mesoscale discussion at May 18, 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 18, 2021, 8:54 PM CDT (01:54 UTC)
- Expired
- May 18, 2021, 10:30 PM CDT
- In force
- 96 min
- Issued by
- the Storm Prediction Center
- Concerning
- Tornado watch 188...190
Counties Austin County, TX, Fort Bend County, TX, Harris County, TX, Jackson County, TX, Montgomery County, TX, Waller County, TX, Wharton County, TX
The radar
The Houston radar (KHGX), 94 km from the middle of the area, began a volume at 01:58 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 00:00Z, 1.9 hours before the alert went out and 252 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
- 2386 J/kg
- Mixed-layer CIN
- -17 J/kg
- Mixed-layer LCL
- 721 m above ground
- 0-6 km bulk shear
- 22 kt
- 0-1 km storm-relative helicity
- 59 m²/s²
- 0-3 km storm-relative helicity
- 114 m²/s²
- Significant tornado parameter
- 0.8
- Supercell composite
- 6.4
The text
As transmitted.
580
ACUS11 KWNS 190155
SWOMCD
SPC MCD 190154
TXZ000-190330-
Mesoscale Discussion 0681
NWS Storm Prediction Center Norman OK
0854 PM CDT Tue May 18 2021
Areas affected...Southeast TX
Concerning...Tornado Watch 188...190...
Valid 190154Z - 190330Z
The severe weather threat for Tornado Watch 188, 190 continues.
SUMMARY...The threat for damaging wind and a tornado or two will
continue as an ongoing MCS moves eastward tonight.
DISCUSSION...Convection across southeast TX has consolidated into an
eastward-propagating MCS. Favorable instability (MLCAPE of 1500-2000
J/kg) and sufficient effective shear (30-40 kt) will continue to
favor some organization as the system progresses across southeast
TX. Locally damaging wind will be possible, especially near the
bowing portion of the line as it approaches the Houston area between
02-03Z. The KHGX VWP continues to show moderately strong low-level
southeasterly flow with some veering with height, which will support
transient supercell structures capable of a tornado or two, and
perhaps some hail.
..Dean.. 05/19/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...HGX...CRP...EWX...
LAT...LON 28839682 29669638 30189628 30439616 30569596 30639558
30429528 29969528 29459548 29119581 28979601 28819638
28839682SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 18, 7:34 PM CDT | Tornado Watch | SPC | Austin, Bee, Brazoria, Chambers, Colorado, Fort Bend and 17 more | 6 hr |
| May 18, 8:00 PM CDT | Mesoscale Discussion | SPC | Cherokee, Gregg, Harrison, Marion, Nacogdoches, Panola and 4 more | 60 min |
| May 18, 10:39 PM CDT | Mesoscale Discussion | SPC | Hardin, Jasper, Jefferson, Newton, Orange, Tyler | 96 min |
| May 18, 11:00 PM CDT | Mesoscale Discussion | SPC | Dimmit, Duval, Jim Hogg, La Salle, Webb, Zapata | 90 min |
| May 19, 3:32 AM CDT | Mesoscale Discussion | SPC | Brooks, Dimmit, Duval, Hidalgo, Jim Hogg, Jim Wells and 5 more | 118 min |
| May 19, 5:24 AM CDT | Severe Thunderstorm Watch | SPC | Brooks, Cameron, Duval, Hidalgo, Jim Hogg, Jim Wells and 8 more | 8 hr |
| May 19, 7:09 AM CDT | Mesoscale Discussion | SPC | Hidalgo, Jim Hogg, Starr | 96 min |
| May 19, 8:46 AM CDT | Mesoscale Discussion | SPC | Brooks, Cameron, Hidalgo, Kenedy, Willacy | 89 min |
| May 19, 2:10 PM CDT | Mesoscale Discussion | SPC | Callahan, Coke, Coleman, Concho, Crane, Crockett and 24 more | 3 hr |
| May 19, 6:06 PM CDT | Mesoscale Discussion | SPC | Crane, Crockett, Ector, Glasscock, Irion, Midland and 6 more | 84 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.