Alert archive / Louisiana / Mesoscale Discussions in 2011

Mesoscale Discussion 976

May 26, 201116 parishes in Louisiana; 14 counties in Mississippi

The Storm Prediction Center issued this mesoscale discussion at May 26, 2011, 2:05 AM CDT for 16 parishes in Louisiana; 14 counties in Mississippi. It was in force for 85 min.

The area

The outline as issued.

The facts

Issued: May 26, 2011, 2:05 AM CDT (07:05 UTC)
Expired: May 26, 2011, 3:30 AM CDT
In force: 85 min
Issued by: the Storm Prediction Center

All 30 counties

Ascension Parish, LA, East Baton Rouge Parish, LA, East Feliciana Parish, LA, Iberville Parish, LA, Livingston Parish, LA, Orleans Parish, LA, Pointe Coupee Parish, LA, Saint Helena Parish, LA, Saint James Parish, LA, Saint John the Baptist Parish, LA, Saint Martin Parish, LA, Saint Tammany Parish, LA, Tangipahoa Parish, LA, Washington Parish, LA, West Baton Rouge Parish, LA, West Feliciana Parish, LA, Amite County, MS, Forrest County, MS, Greene County, MS, Hancock County, MS, Harrison County, MS, Jones County, MS, Lamar County, MS, Marion County, MS, Pearl River County, MS, Perry County, MS, Pike County, MS, Stone County, MS, Walthall County, MS, Wayne County, MS

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 00:00Z, 7.1 hours before the alert went out and 96 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: 2631 J/kg
Mixed-layer CIN: -2 J/kg
Mixed-layer LCL: 910 m above ground
0-6 km bulk shear: 27 kt
0-1 km storm-relative helicity: 52 m²/s²
0-3 km storm-relative helicity: 78 m²/s²
Significant tornado parameter: 0.8
Supercell composite: 4.6

Open this sounding in Storm Lab

The text

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

882 
ACUS11 KWNS 260706
SWOMCD
SPC MCD 260705
ALZ000-MSZ000-LAZ000-260830-

MESOSCALE DISCUSSION 0976
NWS STORM PREDICTION CENTER NORMAN OK
0205 AM CDT THU MAY 26 2011

AREAS AFFECTED...SOUTHERN LA/SOUTHEAST MS INTO FAR SOUTHWEST AL

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 260705Z - 260830Z

AT LEAST ISOLATED SEVERE TSTMS ARE EXPECTED TO CONTINUE TO DEVELOP
ACROSS SOUTHEAST LA/FAR SOUTHERN MS AND PERHAPS SOUTHWEST AL THROUGH
THE EARLY MORNING HOURS. A WATCH MAY BE NEEDED.

SEVERAL STRONG/SEVERE TSTMS CONTINUE TO PROGRESS EAST-SOUTHEASTWARD
ALONG THE LA/MS BORDER VICINITY EARLY IN THE OVERNIGHT...WITH A
MODEST INCREASE IN SMALL SCALE QUASI-LINEAR ORGANIZATION NOTED OVER
THE PAST HOUR OR SO. AN APPROACHING/ARCING LOBE OF DPVA/ATTENDANT
HEIGHT FALLS AS IMPLIED PER WATER VAPOR IMAGERY SHOULD CONTINUE TO
SUPPORT ADDITIONAL TSTM DEVELOPMENT OVERNIGHT...WITH SHORT TERM
NUMERICAL GUIDANCE ACTUALLY SUGGESTIVE OF WEAKENING CINH THROUGH THE
EARLY MORNING HOURS. IN CONJUNCTION WITH STRENGTHENING FLOW
ALOFT...RELATIVELY MOIST/UNSTABLE INFLOW /MAINLY JUST ABOVE THE
SURFACE/ AS PER THE 00Z OBSERVED LCH/LIX RAOBS WILL YIELD SUSTAINED
STRONG UPDRAFTS CAPABLE OF SEVERE HAIL/WINDS AND PERHAPS A TORNADO.

..GUYER.. 05/26/2011

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

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

LAT...LON   29869237 31159123 31838836 30088887 29869237

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 25, 7:22 PM CDT	Mesoscale Discussion	SPC	Union	53 min
May 25, 7:45 PM CDT	Mesoscale Discussion	SPC	Bienville, Caldwell, De Soto, Grant, Jackson, Lincoln and 9 more	60 min
May 25, 9:43 PM CDT	Tornado Watch	SPC	Avoyelles, Caldwell, Catahoula, Concordia, East Carroll, Franklin and 14 more	5 hr
May 26, 5:18 PM CDT	Mesoscale Discussion	SPC	Orleans, Saint Bernard, Saint Tammany	57 min
May 25, 8:33 PM CDT	Tornado Watch	SPC	Alcorn, Benton, Calhoun, Chickasaw, DeSoto, Itawamba and 14 more	7 hr
May 25, 10:27 PM CDT	Mesoscale Discussion	SPC	Attala, Calhoun, Carroll, Chickasaw, Choctaw, Clay and 14 more	2 hr
May 26, 7:56 AM CDT	Mesoscale Discussion	SPC	Lowndes	94 min
May 26, 12:22 PM CDT	Mesoscale Discussion	SPC	Clarke, Covington, Forrest, George, Greene, Jasper and 6 more	83 min

Nearby

Mesoscale Discussions in Louisiana, 2011 Mesoscale Discussions in Mississippi, 2011 Every 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.