Alert archive / Louisiana / Mesoscale Discussions in 2016

Mesoscale Discussion 313

March 31, 201615 parishes in Louisiana

The Storm Prediction Center issued this mesoscale discussion at Mar 31, 2016, 5:22 PM CDT for 15 parishes in Louisiana. It was in force for 53 min.

The area

The outline as issued.

The facts

Issued: Mar 31, 2016, 5:22 PM CDT (22:22 UTC)
Expired: Mar 31, 2016, 6:15 PM CDT
In force: 53 min
Issued by: the Storm Prediction Center

Counties Caldwell Parish, LA, Catahoula Parish, LA, East Carroll Parish, LA, Franklin Parish, LA, Grant Parish, LA, Jackson Parish, LA, LaSalle Parish, LA, Madison Parish, LA, Morehouse Parish, LA, Natchitoches Parish, LA, Ouachita Parish, LA, Richland Parish, LA, Tensas Parish, LA, West Carroll Parish, LA, Winn Parish, LA

The radar

The Ft Polk radar (KPOE), 134 km from the middle of the area, began a volume at 22:23 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The nearest sounding before it

Shreveport, LA (KBAD), launched 12:00Z, 10.4 hours before the alert went out and 163 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.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 1130 J/kg
Mixed-layer CIN: -143 J/kg
Mixed-layer LCL: 602 m above ground
0-6 km bulk shear: 35 kt
0-1 km storm-relative helicity: 187 m²/s²
0-3 km storm-relative helicity: 166 m²/s²
Significant tornado parameter: 0.6
Supercell composite: 2.0

Open this sounding in Storm Lab

The text

As transmitted.

404 
ACUS11 KWNS 312223
SWOMCD
SPC MCD 312222 
MSZ000-LAZ000-ARZ000-312315-

MESOSCALE DISCUSSION 0313
NWS STORM PREDICTION CENTER NORMAN OK
0522 PM CDT THU MAR 31 2016

AREAS AFFECTED...NRN LA

CONCERNING...SEVERE THUNDERSTORM WATCH 69...

VALID 312222Z - 312315Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 69
CONTINUES.

SUMMARY...SEMI-DISCRETE SUPERCELLS PRODUCING LARGE HAIL SHOULD
PERSIST FOR THE NEXT FEW HOURS BEFORE MAINLY SHIFTING INTO WW 70.

DISCUSSION...A COUPLE SUPERCELLS ACROSS NRN LA ARE BEING SUPPORTED
BY STEEP MID-LEVEL LAPSE RATES WITHIN A PERSISTENT EML PLUME AND
ROBUST MID/UPPER-LEVEL SPEED SHEAR PER POE/JAN VWP DATA. WHILE
VEERED LOW-LEVEL FLOW AHEAD OF THE IMPINGING COLD FRONT SHOULD LIMIT
THE TORNADO RISK...THE MOSTLY DISCRETE NATURE OF THE CONVECTION WILL
CONTINUE TO SUPPORT A PRIMARY RISK OF LARGE HAIL. CURRENT CONVECTIVE
TRENDS SUGGEST THE BULK OF THE SEVERE THREAT SHOULD SHIFT INTO WW 70
BY ABOUT 01Z.

..GRAMS.. 03/31/2016

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...JAN...LCH...SHV...

LAT...LON   32139303 32919200 33049163 33039117 32329114 31919133
            31579150 31359179 31359235 31529286 31759316 32139303

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Mar 30, 8:39 PM CDT	Mesoscale Discussion	SPC	Bienville, Bossier, Caddo, Caldwell, Claiborne, De Soto and 13 more	96 min
Mar 30, 10:00 PM CDT	Tornado Watch	SPC	Bienville, Caldwell, Catahoula, Claiborne, Concordia, East Carroll and 16 more	6 hr
Mar 30, 11:30 PM CDT	Mesoscale Discussion	SPC	Catahoula, Concordia, East Carroll, Franklin, Madison, Morehouse and 3 more	60 min
Mar 31, 3:04 AM CDT	Mesoscale Discussion	SPC	East Feliciana, Pointe Coupee, Saint Helena, Tangipahoa, Washington, West Feliciana	86 min
Mar 31, 3:20 AM CDT	Tornado Watch	SPC	East Baton Rouge, East Feliciana, Livingston, Pointe Coupee, Saint Helena, Saint Tammany and 4 more	6 hr
Mar 31, 1:30 PM CDT	Mesoscale Discussion	SPC	Avoyelles, Caldwell, Catahoula, Concordia, East Carroll, Franklin and 12 more	2 hr
Mar 31, 2:05 PM CDT	Severe Thunderstorm Watch	SPC	Avoyelles, Bienville, Caldwell, Catahoula, Claiborne, Concordia and 20 more	8 hr
Mar 31, 3:30 PM CDT	Mesoscale Discussion	SPC	Ascension, East Baton Rouge, East Feliciana, Iberville, Livingston, Pointe Coupee and 6 more	2 hr

Nearby

Mesoscale Discussions in Louisiana, 2016 Every mesoscale discussion in 2016

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; radar from the NEXRAD Level II archive.