Alert archive / Louisiana / Mesoscale Discussions in 2012
Mesoscale Discussion 247
The Storm Prediction Center issued this mesoscale discussion at Mar 12, 2012, 8:55 AM CDT for 11 parishes in Louisiana. It was in force for 65 min.
The area
The outline as issued.
The facts
- Issued
- Mar 12, 2012, 8:55 AM CDT (13:55 UTC)
- Expired
- Mar 12, 2012, 10:00 AM CDT
- In force
- 65 min
- Issued by
- the Storm Prediction Center
Counties Acadia Parish, LA, Ascension Parish, LA, Assumption Parish, LA, Iberville Parish, LA, Jefferson Davis Parish, LA, Lafayette Parish, LA, Saint James Parish, LA, Saint John the Baptist Parish, LA, Saint Landry Parish, LA, Saint Martin Parish, LA, West Baton Rouge Parish, LA
The nearest sounding before it
Lake Charles Mun, LA (KLCH), launched 12:00Z, 1.9 hours before the alert went out and 154 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
- 1900 J/kg
- Mixed-layer CIN
- -1 J/kg
- Mixed-layer LCL
- 441 m above ground
- 0-6 km bulk shear
- 32 kt
- 0-1 km storm-relative helicity
- 111 m²/s²
- 0-3 km storm-relative helicity
- 116 m²/s²
- Significant tornado parameter
- 0.8
- Supercell composite
- 4.4
The text
As transmitted, in the capitals the NWS used until 2016.
251
ACUS11 KWNS 121356
SWOMCD
SPC MCD 121355
LAZ000-121500-
MESOSCALE DISCUSSION 0247
NWS STORM PREDICTION CENTER NORMAN OK
0855 AM CDT MON MAR 12 2012
AREAS AFFECTED...SRN LA
CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY
VALID 121355Z - 121500Z
A THREAT FOR ISOLATED DMGG WIND GUSTS...AND PERHAPS A BRIEF/WEAK
TORNADO...MAY EXIST THROUGH LATE MORNING ACROSS SRN LA. A WW IS NOT
CURRENTLY ANTICIPATED...BUT CONVECTIVE TRENDS WILL CONTINUE TO BE
MONITORED.
WATER VAPOR LOOP SHOWS A FOCUSED ZONE OF ASCENT ACCOMPANYING A WEAK
UPPER IMPULSE MOVING ACROSS THE WRN GULF...OVERSPREADING A NEARLY
STATIONARY OUTFLOW BOUNDARY /ANALYZED 20 WNW LFT TO 30 S BTR TO 15
NNW BVE AT 13Z/. RADAR TRENDS INDICATE LOOSELY ORGANIZED TSTMS
DEVELOPING FROM SWRN INTO S-CNTRL LA...WITH THE STRONGER CELLS
OCCASIONALLY EXHIBITING WEAK ROTATION. LOCALLY ENHANCED LOW-LEVEL
HELICITY ALONG/N OF THE OUTFLOW BOUNDARY /WITH 10-15 KTS OF ESELY
0-1 KM AGL LAYER FLOW AND 20-30 KTS OF SWLY MIDLEVEL FLOW/ SHOULD
CONTINUE TO SUPPORT THE POTENTIAL FOR WEAKLY ROTATING TSTMS. AS
SUCH...WITH A MOIST BOUNDARY LAYER / LOW LCL/S PRESENT...A THREAT
FOR A BRIEF/WEAK TORNADO AND/OR DMGG WIND GUST MAY EXIST
ALONG/IMMEDIATELY N OF THE OUTFLOW BOUNDARY. EVOLUTION OF ONGOING
TSTMS IS SOMEWHAT UNCLEAR...BUT WITH STRONG SFC
HEATING/DESTABILIZATION LIKELY TO OCCUR OVER SERN LA...ACTIVITY MAY
PERSIST WELL INTO THE LATE MORNING.
..ROGERS.. 03/12/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...LIX...LCH...
LAT...LON 29599041 29799110 29969180 30039235 30009276 30179296
30489280 30659246 30709206 30679179 30579131 30489097
30139044 29769031 29599041SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Mar 11, 8:44 PM CDT | Mesoscale Discussion | SPC | Acadia, Avoyelles, Catahoula, Concordia, East Carroll, Evangeline and 7 more | 91 min |
| Mar 11, 11:17 PM CDT | Mesoscale Discussion | SPC | Acadia, Ascension, Assumption, East Baton Rouge, Iberia, Iberville and 11 more | 88 min |
| Mar 12, 1:23 AM CDT | Mesoscale Discussion | SPC | Ascension, Assumption, Iberia, Iberville, Livingston, Saint Charles and 5 more | 2 hr |
| Mar 12, 4:02 PM CDT | Mesoscale Discussion | SPC | East Carroll, Madison, Richland, West Carroll | 58 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.