Alert archive / Texas / Mesoscale Discussions in 2017
Mesoscale Discussion 367
The Storm Prediction Center issued this mesoscale discussion at Mar 29, 2017, 8:23 AM CDT for 18 counties in Texas. It was in force for 67 min.
The area
The outline as issued.
The facts
- Issued
- Mar 29, 2017, 8:23 AM CDT (13:23 UTC)
- Expired
- Mar 29, 2017, 9:30 AM CDT
- In force
- 67 min
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 40%
Counties Brazoria County, TX, Calhoun County, TX, Chambers County, TX, Fort Bend County, TX, Galveston County, TX, Hardin County, TX, Harris County, TX, Jackson County, TX, Jasper County, TX, Jefferson County, TX, Liberty County, TX, Matagorda County, TX, Montgomery County, TX, Polk County, TX, San Jacinto County, TX, Tyler County, TX, Waller County, TX, Wharton County, TX
The radar
The Houston radar (KHGX), 49 km from the middle of the area, began a volume at 13:24 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
Lake Charles Mun, LA (KLCH), launched 12:00Z, 1.4 hours before the alert went out and 238 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
- 451 J/kg
- Mixed-layer CIN
- -384 J/kg
- Mixed-layer LCL
- 879 m above ground
- 0-6 km bulk shear
- 27 kt
- 0-1 km storm-relative helicity
- 162 m²/s²
- 0-3 km storm-relative helicity
- 229 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.1
The text
As transmitted.
588
ACUS11 KWNS 291323
SWOMCD
SPC MCD 291323
TXZ000-291430-
Mesoscale Discussion 0367
NWS Storm Prediction Center Norman OK
0823 AM CDT Wed Mar 29 2017
Areas affected...Southeast Texas
Concerning...Severe potential...Watch possible
Valid 291323Z - 291430Z
Probability of Watch Issuance...40 percent
SUMMARY...An isolated severe threat is expected to move across
southeast Texas over the next few hours. A few damaging wind gusts
and perhaps a brief tornado may occur with short bowing line
segments. However threat threat should remain marginal for WW
issuance.
DISCUSSION...The latest radar imagery shows a continuous line of
thunderstorms located from about 40 statute miles west of Houston
extending south southwestward to the vicinity of Victoria. The line
appears to be located along an old outflow boundary. Ahead of this
line, a moist airmass is present with surface dewpoints in the upper
60s F with moderate instability in place (MLCAPE of 1000 to 1500
J/kg). The line of storms is being supported by a subtle shortwave
trough moving around an upper-level low in the southern high Plains
and this will help maintain the line as it moves across the
remainder of southeast Texas over the next few hours. Concerning the
environment, the Houston WSR-88D VWP shows substantial directional
shear in the boundary layer with ample speed shear above 2 km AGL.
This is resulting in about 70 kt of 0-6 km shear suggesting storm
organization will be possible with this convection. The current
thinking is that this line will continue to have an isolated severe
threat and that a few damaging wind gusts will occur as the line
moves across the Houston area. A brief tornado can also not be ruled
out but low-level shear appears to be marginal for a more sustained
tornado threat.
..Broyles/Guyer.. 03/29/2017
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...LCH...HGX...CRP...
LAT...LON 30879545 29429642 28599715 28199652 28089572 29609410
30859382 30879545SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Mar 28, 7:45 PM CDT | Mesoscale Discussion | SPC | Armstrong, Briscoe, Carson, Castro, Crosby, Deaf Smith and 9 more | 60 min |
| Mar 28, 9:07 PM CDT | Mesoscale Discussion | SPC | Bandera, Bexar, Blanco, Brown, Burnet, Callahan and 37 more | 23 min |
| Mar 28, 9:28 PM CDT | Severe Thunderstorm Watch | SPC | Atascosa, Bandera, Bell, Bexar, Blanco, Bosque and 78 more | 8 hr |
| Mar 28, 10:21 PM CDT | Severe Thunderstorm Watch | SPC | Archer, Baylor, Clay, Wichita, Wilbarger | 7 hr |
| Mar 28, 10:25 PM CDT | Mesoscale Discussion | SPC | Archer, Clay, Cooke, Montague, Wichita | 65 min |
| Mar 28, 11:58 PM CDT | Mesoscale Discussion | SPC | Anderson, Bastrop, Bell, Bexar, Blanco, Bosque and 29 more | 92 min |
| Mar 29, 2:54 AM CDT | Mesoscale Discussion | SPC | Collin, Delta, Fannin, Franklin, Grayson, Hopkins and 7 more | 96 min |
| Mar 29, 1:31 PM CDT | Mesoscale Discussion | SPC | Brazoria, Chambers, Galveston, Hardin, Harris, Jasper and 7 more | 2 hr |
| Mar 29, 2:11 PM CDT | Tornado Watch | SPC | Angelina, Chambers, Galveston, Hardin, Jasper, Jefferson and 6 more | 7 hr |
| Mar 29, 4:17 PM CDT | Tornado Watch | SPC | Bowie, Cass, Morris | 8 hr |
| Mar 29, 5:50 PM CDT | Mesoscale Discussion | SPC | Jasper, Newton, Orange | 115 min |
Nearby
Mesoscale Discussions in Texas, 2017Every mesoscale discussion in 2017
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.