Alert archive / Louisiana / Mesoscale Discussions in 2018

Mesoscale Discussion 819

June 22, 20188 counties in Arkansas; 20 parishes in Louisiana; 7 counties in Mississippi

The Storm Prediction Center issued this mesoscale discussion at Jun 22, 2018, 8:42 AM CDT for 8 counties in Arkansas; 20 parishes in Louisiana; 7 counties in Mississippi. It was in force for 93 min.

The area

The outline as issued.

The facts

Issued: Jun 22, 2018, 8:42 AM CDT (13:42 UTC)
Expired: Jun 22, 2018, 10:15 AM CDT
In force: 93 min
Issued by: the Storm Prediction Center
Chance of a watch: 20%

All 35 counties

Ashley County, AR, Bradley County, AR, Calhoun County, AR, Chicot County, AR, Columbia County, AR, Drew County, AR, Lafayette County, AR, Union County, AR, Bienville Parish, LA, Bossier Parish, LA, Caldwell Parish, LA, Claiborne Parish, LA, East Carroll Parish, LA, Franklin Parish, LA, Jackson Parish, LA, LaSalle Parish, LA, Lincoln Parish, LA, Madison Parish, LA, Morehouse Parish, LA, Natchitoches Parish, LA, Ouachita Parish, LA, Red River Parish, LA, Richland Parish, LA, Tensas Parish, LA, Union Parish, LA, Webster Parish, LA, West Carroll Parish, LA, Winn Parish, LA, Claiborne County, MS, Hinds County, MS, Issaquena County, MS, Jefferson County, MS, Sharkey County, MS, Warren County, MS, Washington County, MS

The radar

The Shreveport radar (KSHV), 154 km from the middle of the area, began a volume at 13:44 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 watches that followed

Watches SPC issued over any of the same counties within four hours of this discussion.

Severe Thunderstorm Watch 197Jun 22, 10:50 AM CDT

The nearest sounding before it

Shreveport, LA (KBAD), launched 12:00Z, 1.7 hours before the alert went out and 145 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: 2162 J/kg
Mixed-layer CIN: -57 J/kg
Mixed-layer LCL: 620 m above ground
0-6 km bulk shear: 38 kt
0-1 km storm-relative helicity: 52 m²/s²
0-3 km storm-relative helicity: 47 m²/s²
Significant tornado parameter: 0.7
Supercell composite: 4.0

Open this sounding in Storm Lab

The text

As transmitted.

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SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jun 21, 8:30 PM CDT	Mesoscale Discussion	SPC	Crittenden, Cross, St. Francis	2 hr
Jun 22, 10:55 AM CDT	Severe Thunderstorm Watch	SPC	Columbia, Union	10 hr
Jun 22, 3:03 PM CDT	Mesoscale Discussion	SPC	Ashley, Columbia, Union	87 min
Jun 22, 6:05 PM CDT	Mesoscale Discussion	SPC	East Carroll, Franklin, Madison, Morehouse, Ouachita, Richland and 2 more	115 min
Jun 22, 9:09 AM CDT	Mesoscale Discussion	SPC	Calhoun, Carroll, Chickasaw, Choctaw, Clay, Grenada and 15 more	96 min
Jun 22, 12:35 PM CDT	Mesoscale Discussion	SPC	Chickasaw, Clay, Itawamba, Lee, Lowndes, Monroe and 4 more	85 min

Nearby

Mesoscale Discussions in Louisiana, 2018 Mesoscale Discussions in Arkansas, 2018 Mesoscale Discussions in Mississippi, 2018 Every mesoscale discussion in 2018

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.