Alert archive / Texas / Mesoscale Discussions in 2012
Mesoscale Discussion 791
The Storm Prediction Center issued this mesoscale discussion at May 11, 2012, 7:28 PM CDT for 16 counties in Texas. It was in force for 32 min.
The area
The outline as issued.
The facts
- Issued
- May 11, 2012, 7:28 PM CDT (00:28 UTC)
- Expired
- May 11, 2012, 8:00 PM CDT
- In force
- 32 min
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 95%
Counties Austin County, TX, Brazoria County, TX, Chambers County, TX, Fort Bend County, TX, Hardin County, TX, Harris County, TX, Jasper County, TX, Jefferson County, TX, Liberty County, TX, Montgomery County, TX, Polk County, TX, San Jacinto County, TX, Tyler County, TX, Walker County, TX, Waller County, TX, Wharton County, TX
The radar
The Houston radar (KHGX), 83 km from the middle of the area, began a volume at 00:29 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
Lake Charles Mun, LA (KLCH), launched 00:00Z, 0.5 hours before the alert went out and 208 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
- 21 J/kg
- Mixed-layer CIN
- -209 J/kg
- Mixed-layer LCL
- 694 m above ground
- 0-6 km bulk shear
- 40 kt
- 0-1 km storm-relative helicity
- 45 m²/s²
- 0-3 km storm-relative helicity
- 117 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- -0.2
The text
As transmitted, in the capitals the NWS used until 2016.
744
ACUS11 KWNS 120028
SWOMCD
SPC MCD 120028
TXZ000-120100-
MESOSCALE DISCUSSION 0791
NWS STORM PREDICTION CENTER NORMAN OK
0728 PM CDT FRI MAY 11 2012
AREAS AFFECTED...SERN TX...SWRN LA
CONCERNING...SEVERE POTENTIAL...WATCH NEEDED SOON
VALID 120028Z - 120100Z
PROBABILITY OF WATCH ISSUANCE...95 PERCENT
SUMMARY...A TORNADO WATCH WILL BE ISSUED FOR PORTIONS OF SERN TX.
DISCUSSION...STRONG LOW-LEVEL SHEAR AMIDST RICH LOW-LEVEL
MOISTURE/SUFFICIENT BUOYANCY WILL SUPPORT A TORNADO THREAT WITH
SUPERCELLS NEAR WARM FRONT AND SFC TROUGH.
ENVIRONMENTAL CONDITIONS HAVE BECOME FAVORABLE FOR SEVERE STORMS AND
A WATCH ISSUANCE WILL BE COORDINATED BETWEEN THE SPC AND THE
AFFECTED LOCAL NATIONAL WEATHER SERVICE OFFICES SHORTLY.
..COHEN/CARBIN.. 05/12/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...LCH...HGX...
LAT...LON 30789570 31029521 30999459 30689382 29719403 29109545
29159627 29609648 29939640 30789570SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 11, 7:36 PM CDT | Tornado Watch | SPC | Brazoria, Chambers, Fort Bend, Galveston, Hardin, Harris and 11 more | 6 hr |
| May 11, 10:31 PM CDT | Mesoscale Discussion | SPC | Brazoria, Chambers, Fort Bend, Galveston, Hardin, Harris and 11 more | 89 min |
| May 12, 1:40 AM CDT | Mesoscale Discussion | SPC | Brazoria, Chambers, Fort Bend, Galveston, Hardin, Harris and 11 more | 65 min |
| May 12, 4:20 PM CDT | Mesoscale Discussion | SPC | Brooks, Cameron, Hidalgo, Willacy | 55 min |
Nearby
Mesoscale Discussions in Texas, 2012Every mesoscale discussion in 2012
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.