Alert archive / Louisiana / Mesoscale Discussions in 2011
Mesoscale Discussion 308
The Storm Prediction Center issued this mesoscale discussion at Mar 29, 2011, 6:47 PM CDT for 39 parishes in Louisiana; 26 counties in Mississippi. It was in force for 118 min.
The area
The outline as issued.
The facts
- Issued
- Mar 29, 2011, 6:47 PM CDT (23:47 UTC)
- Expired
- Mar 29, 2011, 8:45 PM CDT
- In force
- 118 min
- Issued by
- the Storm Prediction Center
All 65 counties
Acadia Parish, LA, Allen Parish, LA, Ascension Parish, LA, Assumption Parish, LA, Avoyelles Parish, LA, Beauregard Parish, LA, Calcasieu Parish, LA, Cameron Parish, LA, Catahoula Parish, LA, Concordia Parish, LA, East Baton Rouge Parish, LA, East Feliciana Parish, LA, Evangeline Parish, LA, Iberia Parish, LA, Iberville Parish, LA, Jefferson Davis Parish, LA, Jefferson Parish, LA, Lafayette Parish, LA, Lafourche Parish, LA, Livingston Parish, LA, Orleans Parish, LA, Pointe Coupee Parish, LA, Rapides Parish, LA, Saint Bernard Parish, LA, Saint Charles Parish, LA, Saint Helena Parish, LA, Saint James Parish, LA, Saint John the Baptist Parish, LA, Saint Landry Parish, LA, Saint Martin Parish, LA, Saint Tammany Parish, LA, St. Mary Parish, LA, Tangipahoa Parish, LA, Terrebonne Parish, LA, Vermilion Parish, LA, Vernon Parish, LA, Washington Parish, LA, West Baton Rouge Parish, LA, West Feliciana Parish, LA, Adams County, MS, Amite County, MS, Copiah County, MS, Covington County, MS, Forrest County, MS, Franklin County, MS, George County, MS, Greene County, MS, Hancock County, MS, Harrison County, MS, Jackson County, MS, Jefferson County, MS, Jefferson Davis County, MS, Jones County, MS, Lamar County, MS, Lawrence County, MS, Lincoln County, MS, Marion County, MS, Pearl River County, MS, Perry County, MS, Pike County, MS, Simpson County, MS, Stone County, MS, Walthall County, MS, Wayne County, MS, Wilkinson County, MS
The watches that followed
Watches SPC issued over any of the same counties within four hours of this discussion.
The nearest sounding before it
Slidell Radar S, LA (KSIL), launched 12:00Z, 11.8 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
- 7 J/kg
- Mixed-layer CIN
- -508 J/kg
- Mixed-layer LCL
- 621 m above ground
- 0-6 km bulk shear
- 33 kt
- 0-1 km storm-relative helicity
- 267 m²/s²
- 0-3 km storm-relative helicity
- 248 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 4.4
The text
As transmitted, in the capitals the NWS used until 2016.
139
ACUS11 KWNS 292347
SWOMCD
SPC MCD 292347
ALZ000-MSZ000-LAZ000-TXZ000-300145-
MESOSCALE DISCUSSION 0308
NWS STORM PREDICTION CENTER NORMAN OK
0647 PM CDT TUE MAR 29 2011
AREAS AFFECTED...SRN LA/SRN MS
CONCERNING...TORNADO WATCH 72...
VALID 292347Z - 300145Z
THE SEVERE WEATHER THREAT FOR TORNADO WATCH 72 CONTINUES.
A SYNOPTIC BAROCLINIC ZONE IS DRAPED FROM NEAR LCH TO JUST NORTH OF
BTR TO 25 MILES SSE OF ASD. THIS FEATURE IS LIFTING NWD AS A WARM
FRONT OVER SERN LA. SFC OBSERVATIONS INDICATE DEWPOINTS IN THE UPPER
60S AND LOWER 70S SOUTH OF THE FRONT...WHERE 23Z RUC OBJECTIVE
ANALYSIS INDICATES MLCAPE VALUES AOA 2000 J/KG. THIS FRONT IS
FORECAST TO BE NUDGED INTO SRN MS DURING THE NEXT FEW HOURS BY
INCREASING SLY LOW-LEVEL FLOW. SURFACE-BASED CONVECTION IS
DEVELOPING NEAR AND SOUTH OF THIS WARM FRONT...AND THIS WILL
CONTINUE TO OCCUR INTO THIS EVENING AS DEEP-LAYER ASCENT INCREASES.
FARTHER TO THE NORTH...A SECONDARY/MESOSCALE WARM FRONT EXTENDS FROM
S-CNTRL INTO SERN MS...AND IS FOLLOWED BY DEWPOINTS IN THE LOWER AND
MIDDLE 60S. BETWEEN THIS FEATURE AND THE SYNOPTIC BOUNDARY...MODEST
CONVECTIVE INHIBITION FOR A SURFACE-BASED PARCEL WILL RESULT IN A
CONTINUED POTENTIAL FOR SLIGHTLY ELEVATED CONVECTION. HOWEVER...AS
THE SYNOPTIC WARM FRONT LIFTS NWD...THIS CONVECTION WILL LIKELY
BECOME SURFACE BASED.
MODERATE TO STRONG DEEP-LAYER SHEAR /52 KT OF 0-6 KM SHEAR PER VWP
AT LIX/ IS ALLOWING CONVECTION TO EXHIBIT SUPERCELLULAR
CHARACTERISTICS...AND THIS WILL LIKELY CONTINUE THROUGH THE EVENING
HOURS. LOW-LEVEL VERTICAL SHEAR IS FORECAST TO INCREASE DURING THE
NEXT FEW HOURS...PARTICULARLY INVOF THE SYNOPTIC WARM FRONT...AS A
LOW-LEVEL JET MATERIALIZES EAST OF A DEEPENING TROUGH EXTENDING FROM
THE OZARKS TOWARD THE SABINE RIVER VALLEY. THIS IS EXPECTED TO
RESULT IN AN INCREASING POTENTIAL FOR TORNADOES ACROSS WW72 THROUGH
THE EVENING HOURS...ESPECIALLY WITH ANY SUPERCELLS. THE CONVECTION
COULD ALSO GROW UPSCALE INTO ONE OR MORE CONVECTIVE CLUSTERS/LINE
SEGMENTS...WITH AN ATTENDANT POTENTIAL FOR DMGG WINDS.
..COHEN.. 03/29/2011
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...MOB...JAN...LIX...LCH...SHV...
LAT...LON 29338969 29159108 29219314 29679373 30649370 31359326
31779163 31959016 31938863 30598836 29758874 29338969SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Mar 29, 2:48 PM CDT | Mesoscale Discussion | SPC | Acadia, Allen, Ascension, Assumption, Beauregard, Calcasieu and 29 more | 87 min |
| Mar 29, 3:17 PM CDT | Tornado Watch | SPC | Acadia, Allen, Ascension, Assumption, Avoyelles, Beauregard and 34 more | 7 hr |
| Mar 29, 5:26 PM CDT | Mesoscale Discussion | SPC | Bienville, Bossier, Caddo, Caldwell, Claiborne, De Soto and 14 more | 2 hr |
| Mar 29, 6:26 PM CDT | Severe Thunderstorm Watch | SPC | Bienville, Bossier, Caddo, Caldwell, Catahoula, Claiborne and 20 more | 8 hr |
Nearby
Mesoscale Discussions in Louisiana, 2011Mesoscale Discussions in Mississippi, 2011Every mesoscale discussion in 2011
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.