Alert archive / Louisiana / Mesoscale Discussions in 2012
Mesoscale Discussion 310
The Storm Prediction Center issued this mesoscale discussion at Mar 20, 2012, 6:33 PM CDT for 9 parishes in Louisiana. It was in force for 117 min.
The area
The outline as issued.
The facts
- Issued
- Mar 20, 2012, 6:33 PM CDT (23:33 UTC)
- Expired
- Mar 20, 2012, 8:30 PM CDT
- In force
- 117 min
- Issued by
- the Storm Prediction Center
Counties Allen Parish, LA, Beauregard Parish, LA, Calcasieu Parish, LA, Grant Parish, LA, Jackson Parish, LA, Natchitoches Parish, LA, Rapides Parish, LA, Vernon Parish, LA, Winn Parish, LA
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, 11.6 hours before the alert went out and 110 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.
906
ACUS11 KWNS 202333
SWOMCD
SPC MCD 202333
LAZ000-TXZ000-210130-
MESOSCALE DISCUSSION 0310
NWS STORM PREDICTION CENTER NORMAN OK
0633 PM CDT TUE MAR 20 2012
AREAS AFFECTED...WRN THROUGH NCNTRL LA
CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE
VALID 202333Z - 210130Z
STORMS TRAINING FROM SWRN THROUGH NCTRL LA WILL CONTINUE TO POSE A
THREAT FOR MAINLY VERY HEAVY RAIN. HOWEVER...A COUPLE OF TORNADOES
CANNOT BE RULED OUT GIVEN THE FAVORABLE KINEMATIC ENVIRONMENT.
SCATTERED STORMS EMBEDDED WITHIN A LARGER STRATIFORM RAIN AREA
CONTINUE TO TRAIN NWD FROM SWRN THROUGH NCTRL LA PROMOTED BY DEEP
LAYER SLY FLOW PARALLEL TO THE CONVECTIVE BAND DOWNSTREAM FROM A
SLOW MOVING CUTOFF UPPER LOW. MOIST PROFILES THROUGH A DEEP LAYER
WITH PW VALUES TO 1.5 INCHES AND TENDENCY FOR THE STORMS TO TRAIN
WILL PROMOTE RAINFALL RATES FROM LOCALLY 1-2 INCHES PER HOUR.
IN ADDITION A STRONG LLJ EXISTS IN THIS REGION BUT IS FORECAST TO
GRADUALLY LIFT NWD LATER IN THE EVENING. UNTIL THEN STORMS WILL
REMAIN IN A KINEMATIC ENVIRONMENT CHARACTERIZED BY 0-1 KM STORM
RELATIVE HELICITY FROM 200-300 M2/S2. DESPITE FAVORABLE LOW LEVEL
HODOGRAPHS...THE WEAK THERMODYNAMIC ENVIRONMENT WILL POSE A LIMITING
FACTOR FOR A MORE WIDESPREAD SEVERE THREAT. NEVERTHELESS TRENDS WILL
CONTINUE TO BE MONITORED FOR EVIDENCE OF PERSISTENT UPDRAFT ROTATION
WITH NWD TRAINING CELLS.
..DIAL.. 03/20/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...LCH...SHV...
LAT...LON 29969373 31229340 32489271 32409216 31619234 30039306
29969373SPC 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, 3:47 PM CDT | Mesoscale Discussion | SPC | Acadia, Allen, Avoyelles, Beauregard, Calcasieu, Caldwell and 13 more | 88 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.