Alert archive / Texas / Mesoscale Discussions in 2012
Mesoscale Discussion 1532
The Storm Prediction Center issued this mesoscale discussion at Jul 21, 2012, 5:37 PM CDT for 37 counties in Texas. It was in force for 83 min.
The area
The outline as issued.
The facts
- Issued
- Jul 21, 2012, 5:37 PM CDT (22:37 UTC)
- Expired
- Jul 21, 2012, 7:00 PM CDT
- In force
- 83 min
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 60%
All 37 counties
Anderson County, TX, Angelina County, TX, Austin County, TX, Bastrop County, TX, Brazos County, TX, Burleson County, TX, Caldwell County, TX, Cherokee County, TX, Colorado County, TX, Falls County, TX, Fayette County, TX, Fort Bend County, TX, Freestone County, TX, Grimes County, TX, Harris County, TX, Henderson County, TX, Houston County, TX, Lee County, TX, Leon County, TX, Liberty County, TX, Limestone County, TX, Madison County, TX, Milam County, TX, Montgomery County, TX, Nacogdoches County, TX, Navarro County, TX, Polk County, TX, Robertson County, TX, San Augustine County, TX, San Jacinto County, TX, Travis County, TX, Trinity County, TX, Tyler County, TX, Walker County, TX, Waller County, TX, Washington County, TX, Williamson County, TX
The radar
The Ft Hood radar (KGRK), 149 km from the middle of the area, began a volume at 22:37 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, 10.6 hours before the alert went out and 256 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
- 534 J/kg
- Mixed-layer CIN
- -230 J/kg
- Mixed-layer LCL
- 2199 m above ground
- 0-6 km bulk shear
- 18 kt
- 0-1 km storm-relative helicity
- 46 m²/s²
- 0-3 km storm-relative helicity
- 108 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.3
The text
As transmitted, in the capitals the NWS used until 2016.
118
ACUS11 KWNS 212238
SWOMCD
SPC MCD 212237
TXZ000-220000-
MESOSCALE DISCUSSION 1532
NWS STORM PREDICTION CENTER NORMAN OK
0537 PM CDT SAT JUL 21 2012
AREAS AFFECTED...SOUTHEAST TEXAS
CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE
VALID 212237Z - 220000Z
PROBABILITY OF WATCH ISSUANCE...60 PERCENT
SUMMARY...DAMAGING WIND THREAT INCREASING LATE THIS AFTERNOON
THROUGH THE EVENING. A CLUSTER OF STORMS OVER E-CNTRL TX MAY
ORGANIZE INTO A LINE WITH SWD EXTENT THIS EVENING. A SEVERE WW MAY
BE REQUIRED WITHIN THE NEXT HOUR SHOULD CONVECTION CONTINUE TO
STRENGTHEN/ORGANIZE.
DISCUSSION...THUNDERSTORMS WERE DEVELOPING ALONG A NEARLY STATIONARY
BOUNDARY IN AXIS OF STRONG INSTABILITY LATE THIS AFTERNOON OVER
E-CNTRL TX. WHILE DEEP LAYER FLOW IS GENERALLY WEAK ACROSS THE
AREA...THERE IS A SMALL POCKET OF 20-30 KT BULK SHEAR DOWNSTREAM OF
CURRENT CONVECTION WHICH MAY HELP STORM ORGANIZATION. WITH PW VALUES
AROUND 1.5-1.75 INCHES AND DCAPE EXCEEDING 1500 J/KG...STRONG
DOWNBURST WINDS ARE POSSIBLE. SHOULD A COLD POOL DEVELOP AS STORMS
TREND TOWARD LINEAR ORGANIZATION THE WIND THREAT WOULD CONTINUE FOR
SEVERAL HOURS AS STORMS GENERALLY MOVE S/SWWD. THEREFORE A SEVERE WW
MAY BE NEEDED WITHIN THE NEXT HOUR SHOULD CONVECTIVE SIGNAL CONTINUE
AN UPWARD TREND.
..LEITMAN/CARBIN.. 07/21/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...LCH...SHV...HGX...FWD...EWX...
LAT...LON 31989461 31549400 30999397 30119479 29549529 29339616
29389681 29689777 30249796 31169738 32069676 32259623
32289529 31989461SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 20, 7:47 PM CDT | Mesoscale Discussion | SPC | Hardin, Jasper, Jefferson, Newton, Orange, Tyler | 88 min |
| Jul 21, 12:45 PM CDT | Mesoscale Discussion | SPC | Angelina, Chambers, Hardin, Jasper, Jefferson, Liberty and 9 more | 3 hr |
| Jul 21, 2:06 PM CDT | Mesoscale Discussion | SPC | Andrews, Archer, Armstrong, Bailey, Baylor, Borden and 64 more | 2 hr |
| Jul 21, 6:14 PM CDT | Severe Thunderstorm Watch | SPC | Anderson, Angelina, Bell, Brazos, Burleson, Cherokee and 42 more | 6 hr |
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.