Alert archive / Texas / Mesoscale Discussions in 2012
Mesoscale Discussion 303
The Storm Prediction Center issued this mesoscale discussion at Mar 20, 2012, 5:26 AM CDT for 9 counties in Texas. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Mar 20, 2012, 5:26 AM CDT (10:26 UTC)
- Expired
- Mar 20, 2012, 7:30 AM CDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
Counties Brazoria County, TX, Calhoun County, TX, Fort Bend County, TX, Harris County, TX, Liberty County, TX, Matagorda County, TX, Montgomery County, TX, Polk County, TX, San Jacinto County, TX
The radar
The Houston radar (KHGX), 71 km from the middle of the area, began a volume at 10:29 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 nearest sounding before it
Corpus Christi, TX (KCRP), launched 00:00Z, 10.4 hours before the alert went out and 237 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
- 2851 J/kg
- Mixed-layer CIN
- -113 J/kg
- Mixed-layer LCL
- 778 m above ground
- 0-6 km bulk shear
- 40 kt
- 0-1 km storm-relative helicity
- 121 m²/s²
- 0-3 km storm-relative helicity
- 88 m²/s²
- Significant tornado parameter
- 0.6
- Supercell composite
- 3.0
The text
As transmitted, in the capitals the NWS used until 2016.
808
ACUS11 KWNS 201026
SWOMCD
SPC MCD 201026
TXZ000-201230-
MESOSCALE DISCUSSION 0303
NWS STORM PREDICTION CENTER NORMAN OK
0526 AM CDT TUE MAR 20 2012
AREAS AFFECTED...SOUTHEAST TEXAS...INCLUDING THE HOUSTON
METROPOLITAN AREA
CONCERNING...SEVERE THUNDERSTORM WATCH 91...
VALID 201026Z - 201230Z
THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 91
CONTINUES.
HOWEVER...THE NEED FOR AN ADDITIONAL WW EAST OF WW 91 IS NOT
CURRENTLY ANTICIPATED. THE POTENTIAL FOR EXCESSIVE RAINFALL MAY
BECOME MORE OF A CONCERN AS CONVECTION SPREADS INTO THE HOUSTON
METROPOLITAN AREA BETWEEN NOW AND 12-13Z.
A SIGNIFICANT SURFACE COLD POOL ON THE SOUTHERN FLANK OF THE
EXTENSIVE EAST TEXAS SQUALL LINE HAS GENERALLY MAINTAINED A 40 KT
EASTWARD PROGRESSION INTO MIDDLE TEXAS COASTAL AREAS. FORWARD
PROPAGATION ACROSS THE COASTAL PLAIN INTO UPPER TEXAS COASTAL
AREAS...INCLUDING THE HOUSTON METROPOLITAN AREA...MAY CONTINUE
THROUGH 11-13Z. HOWEVER...THIS IS EXPECTED TO SLOW AS MID/UPPER
FLOW CONTINUES TO GRADUALLY BACK TO MORE OF A SOUTHERLY
COMPONENT...IN ADVANCE OF THE STILL EVOLVING AND SLOW MOVING
SOUTHERN ROCKIES CLOSED LOW/TROUGH. AS THIS OCCURS...THE DAMAGING
WIND POTENTIAL PROBABLY WILL DIMINISH. LOCALLY EXCESSIVE RAINFALL
LIKELY WILL BECOME THE PRIMARY CONVECTIVE HAZARD...ASSOCIATED WITH
TRAINING/SLOW MOVING CONVECTION SUPPORTED BY INFLOW OF AIR
CHARACTERIZED BY WEAK TO MODERATE CAPE AND SEASONABLY HIGH
PRECIPITABLE WATER UP TO AROUND 1.5 INCHES.
..KERR.. 03/20/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...HGX...CRP...
LAT...LON 27959684 28439679 29149628 29619610 30129584 30669539
31119480 30069480 29219492 28869518 27959684SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Mar 19, 7:28 PM CDT | Tornado Watch | SPC | Anderson, Bell, Bowie, Camp, Cass, Cherokee and 30 more | 9 hr |
| Mar 19, 8:22 PM CDT | Mesoscale Discussion | SPC | Bandera, Bell, Bexar, Blanco, Burnet, Comal and 30 more | 53 min |
| Mar 19, 9:46 PM CDT | Mesoscale Discussion | SPC | Bandera, Bell, Blanco, Burnet, Coryell, Ellis and 18 more | 119 min |
| Mar 19, 11:53 PM CDT | Mesoscale Discussion | SPC | Atascosa, Bastrop, Bell, Bexar, Burleson, Caldwell and 28 more | 67 min |
| Mar 20, 12:48 AM CDT | Severe Thunderstorm Watch | SPC | Aransas, Atascosa, Austin, Bastrop, Bee, Bexar and 52 more | 9 hr |
| Mar 20, 2:43 AM CDT | Mesoscale Discussion | SPC | Aransas, Bee, Calhoun, Colorado, DeWitt, Duval and 13 more | 92 min |
| Mar 20, 9:03 AM CDT | Mesoscale Discussion | SPC | Chambers, Galveston, Hardin, Jasper, Jefferson, Liberty and 6 more | 87 min |
| Mar 20, 9:46 AM CDT | Tornado Watch | SPC | Hardin, Jasper, Jefferson, Newton, Orange, Sabine and 3 more | 7 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.