Alert archive / Louisiana / Mesoscale Discussions in 2012
Mesoscale Discussion 304
The Storm Prediction Center issued this mesoscale discussion at Mar 20, 2012, 9:03 AM CDT for 21 parishes in Louisiana; 12 counties in Texas. It was in force for 87 min.
The area
The outline as issued.
The facts
- Issued
- Mar 20, 2012, 9:03 AM CDT (14:03 UTC)
- Expired
- Mar 20, 2012, 10:30 AM CDT
- In force
- 87 min
- Issued by
- the Storm Prediction Center
All 33 counties
Allen Parish, LA, Beauregard Parish, LA, Bienville Parish, LA, Bossier Parish, LA, Caddo Parish, LA, Calcasieu Parish, LA, Cameron Parish, LA, Claiborne Parish, LA, De Soto Parish, LA, Grant Parish, LA, Jackson Parish, LA, Jefferson Davis Parish, LA, Lincoln Parish, LA, Natchitoches Parish, LA, Rapides Parish, LA, Red River Parish, LA, Sabine Parish, LA, Union Parish, LA, Vernon Parish, LA, Webster Parish, LA, Winn Parish, LA, Chambers County, TX, Galveston County, TX, Hardin County, TX, Jasper County, TX, Jefferson County, TX, Liberty County, TX, Newton County, TX, Orange County, TX, Sabine County, TX, San Augustine County, TX, Shelby County, TX, Tyler County, TX
The radar
The Lake Charles radar (KLCH), 87 km from the middle of the area, began a volume at 14:03 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 12:00Z, 2.1 hours before the alert went out and 88 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
- 1368 J/kg
- Mixed-layer CIN
- -14 J/kg
- Mixed-layer LCL
- 555 m above ground
- 0-6 km bulk shear
- 40 kt
- 0-1 km storm-relative helicity
- 225 m²/s²
- 0-3 km storm-relative helicity
- 338 m²/s²
- Significant tornado parameter
- 1.2
- Supercell composite
- 8.8
The text
As transmitted, in the capitals the NWS used until 2016.
049
ACUS11 KWNS 201404
SWOMCD
SPC MCD 201403
LAZ000-ARZ000-TXZ000-201530-
MESOSCALE DISCUSSION 0304
NWS STORM PREDICTION CENTER NORMAN OK
0903 AM CDT TUE MAR 20 2012
AREAS AFFECTED...FAR SOUTHEAST TX/WESTERN LA TO FAR SOUTHERN AR
CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE
VALID 201403Z - 201530Z
SEVERE TSTM WATCH 91 HAS BEEN TEMPORALLY EXTENDED /15Z/ ACROSS
COASTAL SOUTHEAST TX...FOR A LOCALIZED WIND DAMAGE/TORNADO THREAT
ASIDE FROM HEAVY RAINFALL. TO THE EAST OF WW 91...MONITORING FOR AN
INCREASING TORNADO/WIND DAMAGE THREAT FROM FAR EAST TX INTO LA AND
PERHAPS EVENTUALLY FAR SOUTHERN AR. A TORNADO WATCH MAY BE NEEDED
WITHIN THE HOUR ESPECIALLY FOR FAR SOUTHEAST TX/SOUTHWEST LA.
FOCUSED ALONG COMPOSITE OUTFLOW...A SQUALL LINE CONTINUES TO MAKE A
SLOW BUT STEADY GENERAL EASTWARD PROGRESSION THIS MORNING ACROSS FAR
EASTERN TX/UPPER TX COASTAL PLAIN. AHEAD OF THIS LINE...SHORT TERM
FORECAST SOUNDINGS SUGGEST THAT THE WARM LAYER ALOFT /GENERALLY
CENTERED 700 MB/ AS NOTED PER 12Z OBSERVED SOUNDINGS FROM SHREVEPORT
AND LAKE CHARLES SHOULD ABATE THROUGH ASCENT AND SQUALL
LINE/COMPOSITE OUTFLOW UPLIFT. ACCORDINGLY...AS THE PRE-CONVECTIVE
LINE DIURNALLY HEATS /ALBEIT MODESTLY/...AN ALREADY
MOIST/UNINHIBITED BOUNDARY LAYER SHOULD ALLOW FOR GRADUAL UPDRAFT
INTENSIFICATION THROUGH MID/LATE MORNING AND ESPECIALLY AFTERNOON.
WITHIN THE ENTRANCE REGION OF A STRONG SOUTHERLY LOW LEVEL JET...12Z
OBSERVED SOUNDINGS AND MORE RECENT WSR-88D VWP DATA ARE INDICATIVE
OF LONG/MODESTLY CURVING LOW LEVEL HODOGRAPHS...WHICH WILL BE VERY
FAVORABLE FOR LINE-EMBEDDED VORTICIES AND NEAR/PRE-CONVECTIVE LINE
SUPERCELLS CAPABLE OF AT LEAST POCKETS OF WIND DAMAGE AND A FEW
TORNADOES. THE SEVERE THREAT MAY GRADUALLY INCREASE/BECOME A BIT
MORE WIDESPREAD THROUGH THE MORNING /AND ESPECIALLY AFTERNOON/ SUCH
THAT A TORNADO WATCH MAY BE NEEDED ESPECIALLY FOR FAR SOUTHEAST
TX/SOUTHWEST LA.
..GUYER.. 03/20/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...LCH...SHV...HGX...
LAT...LON 28609540 30479478 32209422 33099358 32849236 31479233
29459273 29299397 28609540SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Mar 20, 9:46 AM CDT | Tornado Watch | SPC | Allen, Beauregard, Bienville, Bossier, Caddo, Calcasieu and 18 more | 7 hr |
| Mar 20, 2:26 PM CDT | Mesoscale Discussion | SPC | Allen, Beauregard, Calcasieu, Caldwell, Cameron, Evangeline and 10 more | 94 min |
| Mar 20, 3:47 PM CDT | Mesoscale Discussion | SPC | Acadia, Allen, Avoyelles, Beauregard, Calcasieu, Caldwell and 13 more | 88 min |
| Mar 20, 6:33 PM CDT | Mesoscale Discussion | SPC | Allen, Beauregard, Calcasieu, Grant, Jackson, Natchitoches and 3 more | 117 min |
| 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, 5:26 AM CDT | Mesoscale Discussion | SPC | Brazoria, Calhoun, Fort Bend, Harris, Liberty, Matagorda and 3 more | 2 hr |
Nearby
Mesoscale Discussions in Louisiana, 2012Mesoscale 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.