Alert archive / Louisiana / Mesoscale Discussions in 2012
Mesoscale Discussion 308
The Storm Prediction Center issued this mesoscale discussion at Mar 20, 2012, 3:47 PM CDT for 19 parishes in Louisiana. It was in force for 88 min.
The area
The outline as issued.
The facts
- Issued
- Mar 20, 2012, 3:47 PM CDT (20:47 UTC)
- Expired
- Mar 20, 2012, 5:15 PM CDT
- In force
- 88 min
- Issued by
- the Storm Prediction Center
Counties Acadia Parish, LA, Allen Parish, LA, Avoyelles Parish, LA, Beauregard Parish, LA, Calcasieu Parish, LA, Caldwell Parish, LA, Cameron Parish, LA, Catahoula Parish, LA, Concordia Parish, LA, Evangeline Parish, LA, Franklin Parish, LA, Grant Parish, LA, Jefferson Davis Parish, LA, LaSalle Parish, LA, Madison Parish, LA, Ouachita Parish, LA, Rapides Parish, LA, Richland Parish, LA, Tensas Parish, LA
The nearest sounding before it
Lake Charles Mun, LA (KLCH), launched 12:00Z, 8.8 hours before the alert went out and 78 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.
652
ACUS11 KWNS 202047
SWOMCD
SPC MCD 202047
MSZ000-LAZ000-TXZ000-202215-
MESOSCALE DISCUSSION 0308
NWS STORM PREDICTION CENTER NORMAN OK
0347 PM CDT TUE MAR 20 2012
AREAS AFFECTED...SOUTHWEST/NORTHEAST LA TO FAR WESTERN MS
CONCERNING...TORNADO WATCH 92...
VALID 202047Z - 202215Z
THE SEVERE WEATHER THREAT FOR TORNADO WATCH 92 CONTINUES.
TORNADO WATCH 92 CONTINUES UNTIL 22Z...WITH THE PRIMARY SEVERE
THREAT FOCUSED ACROSS SOUTHWEST LA. GIVEN A SCHEDULED 22Z EXPIRATION
OF WW 92...CURRENT THINKING IS THAT A LOCAL EXTENSION OR WATCH
REPLACEMENT WILL BE NEEDED WITHIN THE HOUR ESPECIALLY FOR SOUTHERN
LA. POTENTIAL CONTINUES FOR ISOLATED DAMAGING WINDS...A TORNADO OR
TWO...ALONG WITH PERSISTENT/REPETITIVE HEAVY RAINFALL.
STRONG UPDRAFTS PERSIST ESPECIALLY ACROSS SOUTHWEST LA IN TANDEM
WITH A COMPOSITE OUTFLOW BOUNDARY...WITH THE OUTFLOW HAVING
OTHERWISE SURGED EASTWARD/WEAKENED ACROSS NORTHEAST LA. WITH LITTLE
CHANGE IN THE WIND PROFILE OVER THE PAST FEW HOURS AS PER WSR-88D
VWP DATA...A MOIST/UNSTABLE BOUNDARY LAYER IN CONJUNCTION WITH A
SURFACE COLD POOL/MESOSCALE PROCESSES WILL REMAIN CONDUCIVE FOR
QLCS-EMBEDDED BOWS/MESOVORTICES ESPECIALLY ACROSS SOUTHERN LA AS THE
LINE CONTINUES A SLOW EASTWARD PROGRESSION. GIVEN THAT ISOLATED
DAMAGING WIND/TORNADO POTENTIAL MAY PERSIST BEYOND 22Z ESPECIALLY
ACROSS SOUTHWEST/SOUTH-CENTRAL LA...A REPLACEMENT WATCH OR WFO
EXTENSION WILL LIKELY BE NEEDED.
..GUYER.. 03/20/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...JAN...LIX...LCH...SHV...
LAT...LON 29049390 30129370 31379297 31939253 32819200 32499095
30999167 29949261 29019270 29049390SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Mar 20, 9:03 AM CDT | Mesoscale Discussion | SPC | Allen, Beauregard, Bienville, Bossier, Caddo, Calcasieu and 15 more | 87 min |
| 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, 6:33 PM CDT | Mesoscale Discussion | SPC | Allen, Beauregard, Calcasieu, Grant, Jackson, Natchitoches and 3 more | 117 min |
Nearby
Mesoscale Discussions in Louisiana, 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.