Alert archive / Mississippi / Mesoscale Discussions in 2015

Mesoscale Discussion 749

May 24, 201524 parishes in Louisiana; 30 counties in Mississippi

The Storm Prediction Center issued this mesoscale discussion at May 24, 2015, 7:42 PM CDT for 24 parishes in Louisiana; 30 counties in Mississippi. It was in force for 93 min.

The area

The outline as issued.

The facts

Issued: May 24, 2015, 7:42 PM CDT (00:42 UTC)
Expired: May 24, 2015, 9:15 PM CDT
In force: 93 min
Issued by: the Storm Prediction Center

All 54 counties

Ascension Parish, LA, Assumption Parish, LA, East Baton Rouge Parish, LA, East Feliciana Parish, LA, Iberville Parish, LA, Jefferson Parish, LA, Lafourche Parish, LA, Livingston Parish, LA, Orleans Parish, LA, Plaquemines Parish, LA, Pointe Coupee 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 Martin Parish, LA, Saint Tammany Parish, LA, St. Mary Parish, LA, Tangipahoa Parish, LA, Terrebonne Parish, LA, Washington Parish, LA, West Baton Rouge Parish, LA, West Feliciana Parish, LA, Adams County, MS, Amite County, MS, Claiborne County, MS, Copiah County, MS, Covington County, MS, Forrest County, MS, Franklin County, MS, Hancock County, MS, Harrison County, MS, Hinds County, MS, Humphreys County, MS, Issaquena County, MS, Jefferson County, MS, Jefferson Davis County, MS, Lamar County, MS, Lawrence County, MS, Lincoln County, MS, Madison County, MS, Marion County, MS, Pearl River County, MS, Pike County, MS, Rankin County, MS, Sharkey County, MS, Simpson County, MS, Smith County, MS, Stone County, MS, Walthall County, MS, Warren County, MS, Wilkinson County, MS, Yazoo County, MS

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 00:00Z, 0.7 hours before the alert went out and 90 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: 1726 J/kg
Mixed-layer CIN: -1 J/kg
Mixed-layer LCL: 962 m above ground
0-6 km bulk shear: 32 kt
0-1 km storm-relative helicity: 126 m²/s²
0-3 km storm-relative helicity: 155 m²/s²
Significant tornado parameter: 0.7
Supercell composite: 3.8

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

580 
ACUS11 KWNS 250042
SWOMCD
SPC MCD 250042 
MSZ000-LAZ000-250215-

MESOSCALE DISCUSSION 0749
NWS STORM PREDICTION CENTER NORMAN OK
0742 PM CDT SUN MAY 24 2015

AREAS AFFECTED...PORTIONS OF SERN LA AND SRN/WRN MS

CONCERNING...TORNADO WATCH 204...

VALID 250042Z - 250215Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 204 CONTINUES.

SUMMARY...THE THREAT FOR A BRIEF TORNADO OR TWO...AS WELL AS LOCALLY
DAMAGING WIND GUSTS MAY PERSIST FOR A FEW HOURS AFTER WW EXPIRATION.
LOCAL EXTENSION IN TIME MAY BE NECESSARY.

DISCUSSION...CLUSTERS AND BROKEN BANDS OF STRONG TO LOCALLY SEVERE
CONVECTION PERSIST ACROSS PORTIONS OF WW 204 THIS EVENING...IN A
REGIME OF VERY MOIST CONFLUENT FLOW. 1-MIN SUPER RAPID SCAN GOES
IMAGERY ILLUSTRATES A FEW MORE VIGOROUS UPDRAFTS IN FAR S-CNTRL LA
AS WELL AS SWRN MS...WHICH ARE BEING AIDED BY AROUND 1000-1500 J/KG
OF MLCAPE. HOWEVER...WITH STRONGER MID-LEVEL FLOW DEPARTING TO THE
NORTH AS WELL AS THE ONSET OF MODEST NOCTURNAL COOLING...A GENERAL
DOWNWARD TREND IN CONVECTIVE INTENSITY IS FORECAST THIS EVENING.
NONETHELESS...SOME MAINTENANCE OR EVEN SLIGHT ENHANCEMENT OF
850-700-MB FLOW AND THE PRESENCE OF AMPLE LOW-LEVEL MOISTURE COULD
EXTEND THE SEVERE THREAT FOR A FEW HOURS AFTER THE CURRENT WW
EXPIRATION. AS SUCH...LOCAL EXTENSION MAY BE REQUIRED TO ACCOUNT FOR
SOME THREAT FOR A TORNADO OR TWO...AS WELL AS LOCALLY DAMAGING WINDS
THIS EVENING.

..PICCA.. 05/25/2015

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

ATTN...WFO...MOB...JAN...LIX...LCH...

LAT...LON   29679192 33489082 32698978 30398867 28798932 29679192

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 25, 2:38 AM CDT	Mesoscale Discussion	SPC	Orleans, Saint Tammany, Washington	3 hr
May 25, 5:15 PM CDT	Mesoscale Discussion	SPC	Bienville, Bossier, Caddo, Caldwell, Claiborne, De Soto and 11 more	90 min
May 25, 5:51 PM CDT	Tornado Watch	SPC	Bienville, Bossier, Caddo, Caldwell, Claiborne, De Soto and 11 more	6 hr
May 25, 6:06 PM CDT	Mesoscale Discussion	SPC	Allen, Beauregard, Calcasieu, Cameron	54 min
May 25, 6:24 PM CDT	Tornado Watch	SPC	Acadia, Allen, Beauregard, Calcasieu, Cameron, Evangeline and 3 more	9 hr
May 24, 8:41 PM CDT	Mesoscale Discussion	SPC	Benton, Marshall, Tippah, Union	64 min
May 25, 9:00 AM CDT	Mesoscale Discussion	SPC	Itawamba, Lee, Monroe	60 min

Nearby

Mesoscale Discussions in Mississippi, 2015 Mesoscale Discussions in Louisiana, 2015 Every mesoscale discussion in 2015

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.