Alert archive / Mississippi / Mesoscale Discussions in 2005

Mesoscale Discussion 558

April 11, 200520 parishes in Louisiana; 21 counties in Mississippi

The Storm Prediction Center issued this mesoscale discussion at Apr 11, 2005, 1:41 PM CDT for 20 parishes in Louisiana; 21 counties in Mississippi. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued
Apr 11, 2005, 1:41 PM CDT (18:41 UTC)
Expired
Apr 11, 2005, 3:45 PM CDT
In force
2 hr
Issued by
the Storm Prediction Center
All 41 counties

Ascension Parish, LA, Assumption Parish, LA, East Baton Rouge Parish, LA, East Feliciana Parish, LA, Iberville Parish, LA, Lafourche Parish, LA, Livingston Parish, LA, Orleans Parish, LA, Pointe Coupee 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, 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, Franklin County, MS, Hinds County, MS, Jefferson County, MS, Jefferson Davis County, MS, Lamar County, MS, Lawrence County, MS, Lincoln County, MS, Marion County, MS, Pearl River County, MS, Pike County, MS, Rankin County, MS, Scott County, MS, Simpson County, MS, Smith County, MS, Walthall 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, 6.7 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-pSkew-T log-p diagram, Slidell Radar S, LA at 12:00Z on 2005-04-11Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 46 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Slidell Radar S, LA at 12:00Z on 2005-04-11The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 185 square meters per square second.19395878Sfc1 km3 km6 km9 kmRMLM
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
46 J/kg
Mixed-layer CIN
-604 J/kg
Mixed-layer LCL
650 m above ground
0-6 km bulk shear
46 kt
0-1 km storm-relative helicity
185 m²/s²
0-3 km storm-relative helicity
273 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

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

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SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 11, 3:12 AM CDTMesoscale DiscussionSPCBeauregard, Bienville, Bossier, Caddo, Calcasieu, Claiborne and 6 more63 min
Apr 11, 3:45 AM CDTSevere Thunderstorm WatchSPCBeauregard, Bienville, Bossier, Caddo, Calcasieu, Claiborne and 12 more7 hr
Apr 11, 3:56 AM CDTMesoscale DiscussionSPCFranklin, Madison, Tensas64 min
Apr 11, 6:53 AM CDTMesoscale DiscussionSPCBeauregard, Bienville, Bossier, Caddo, Calcasieu, Claiborne and 12 more67 min
Apr 11, 9:41 AM CDTMesoscale DiscussionSPCAcadia, Allen, Ascension, Assumption, Avoyelles, Beauregard and 47 more2 hr
Apr 11, 10:15 AM CDTTornado WatchSPCAcadia, Allen, Avoyelles, Beauregard, Bienville, Calcasieu and 25 more9 hr
Apr 11, 12:12 PM CDTMesoscale DiscussionSPCAcadia, Allen, Ascension, Assumption, Avoyelles, Beauregard and 47 more2 hr
Apr 11, 2:05 PM CDTTornado WatchSPCAscension, Assumption, East Baton Rouge, East Feliciana, Iberia, Iberville and 14 more7 hr
Apr 11, 6:35 PM CDTTornado WatchSPCJefferson, Lafourche, Orleans, Saint Bernard, Saint Charles, Saint Tammany and 1 more4 hr
Apr 11, 6:52 PM CDTMesoscale DiscussionSPCAscension, Assumption, East Baton Rouge, East Feliciana, Iberville, Livingston and 9 more83 min
Apr 11, 6:17 AM CDTMesoscale DiscussionSPCDeSoto, Tunica118 min
Apr 11, 1:17 PM CDTMesoscale DiscussionSPCAlcorn, Benton, Coahoma, Itawamba, Lafayette, Lee and 10 more58 min
Apr 11, 1:35 PM CDTTornado WatchSPCAlcorn, Benton, Calhoun, Chickasaw, Itawamba, Lafayette and 10 more5 hr

Nearby

Mesoscale Discussions in Mississippi, 2005Mesoscale Discussions in Louisiana, 2005Every mesoscale discussion in 2005

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.