Alert archive / Louisiana / Mesoscale Discussions in 2012
Mesoscale Discussion 242
The Storm Prediction Center issued this mesoscale discussion at Mar 11, 2012, 2:47 PM CDT for 16 parishes in Louisiana; 4 counties in Texas. It was in force for 118 min.
The area
The outline as issued.
The facts
- Issued
- Mar 11, 2012, 2:47 PM CDT (19:47 UTC)
- Expired
- Mar 11, 2012, 4:45 PM CDT
- In force
- 118 min
- Issued by
- the Storm Prediction Center
Counties Allen Parish, LA, Beauregard Parish, LA, Bienville Parish, LA, Calcasieu Parish, LA, De Soto Parish, LA, Grant Parish, LA, Jackson Parish, LA, LaSalle Parish, LA, Lincoln Parish, LA, Natchitoches Parish, LA, Rapides Parish, LA, Red River Parish, LA, Sabine Parish, LA, Vernon Parish, LA, Webster Parish, LA, Winn Parish, LA, Jasper County, TX, Newton County, TX, Orange County, TX, Sabine County, TX
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, 7.8 hours before the alert went out and 124 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
- 182 J/kg
- Mixed-layer CIN
- -71 J/kg
- Mixed-layer LCL
- 452 m above ground
- 0-6 km bulk shear
- 26 kt
- 0-1 km storm-relative helicity
- 246 m²/s²
- 0-3 km storm-relative helicity
- 294 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 1.1
The text
As transmitted, in the capitals the NWS used until 2016.
274
ACUS11 KWNS 111947
SWOMCD
SPC MCD 111947
LAZ000-TXZ000-112145-
MESOSCALE DISCUSSION 0242
NWS STORM PREDICTION CENTER NORMAN OK
0247 PM CDT SUN MAR 11 2012
AREAS AFFECTED...ERN TX THROUGH WRN LA
CONCERNING...TORNADO WATCH 71...
VALID 111947Z - 112145Z
THE SEVERE WEATHER THREAT FOR TORNADO WATCH 71 CONTINUES.
THREAT FOR ISOLATED TORNADOES AND DAMAGING WIND WILL PERSIST THIS
AFTERNOON FROM SERN TX INTO WRN LA. THE GREATEST RISK FOR ISOLATED
TORNADOES THROUGH 22Z IS EXPECTED FROM SERN TX NEWD THROUGH SWRN AND
CNTRL LA.
STORMS DEVELOPING ALONG PRE-FRONTAL CONVERGENCE AXIS FROM EXTREME NW
LA INTO SERN TX CONTINUE TO SHOW OCCASIONAL UPDRAFT ROTATION AND
LEWP STRUCTURES...BUT SO FAR HAVE MOSTLY REMAINED BELOW SEVERE
LEVELS. PRIMARY LIMITING FACTOR HAS BEEN WEAK LOW-MID LEVEL LAPSE
RATES WHICH HAVE RESULTED IN MARGINAL INSTABILITY AND MODEST UPDRAFT
ACCELERATIONS. NEVERTHELESS...0-1 KM HODOGRAPHS WITH 200-250 M2/S2
STORM RELATIVE HELICITY AND LOW LCLS WILL REMAIN SUFFICIENT FOR A
THREAT OF ISOLATED TORNADOES AS THE LLJ SHIFTS SLOWLY NEWD THROUGH
THETA-E AXIS ACROSS WRN CNTRL LA NEXT FEW HOURS.
..DIAL.. 03/11/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...LCH...SHV...
LAT...LON 29989438 31519396 32829347 32819225 31549215 29929323
29989438SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Mar 11, 11:31 AM CDT | Mesoscale Discussion | SPC | Bossier, Caddo, De Soto, Red River, Sabine | 89 min |
| Mar 11, 11:55 AM CDT | Tornado Watch | SPC | Allen, Beauregard, Bienville, Bossier, Caddo, Calcasieu and 18 more | 7 hr |
| Mar 11, 5:36 PM CDT | Mesoscale Discussion | SPC | Avoyelles, Caldwell, Catahoula, Concordia, East Carroll, Franklin and 12 more | 84 min |
| Mar 11, 6:42 PM CDT | Tornado Watch | SPC | Acadia, Allen, Avoyelles, Caldwell, Cameron, Catahoula and 20 more | 8 hr |
| Mar 11, 7:56 AM CDT | Mesoscale Discussion | SPC | Angelina, Brazoria, Chambers, Fort Bend, Galveston, Hardin and 15 more | 3 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.