Alert archive / Louisiana / Mesoscale Discussions in 2017

Mesoscale Discussion 1734

October 22, 201723 parishes in Louisiana; 11 counties in Mississippi

The Storm Prediction Center issued this mesoscale discussion at Oct 22, 2017, 5:41 AM CDT for 23 parishes in Louisiana; 11 counties in Mississippi. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Oct 22, 2017, 5:41 AM CDT (10:41 UTC)
Expired: Oct 22, 2017, 7:45 AM CDT
In force: 2 hr
Issued by: the Storm Prediction Center
Chance of a watch: 5%

All 34 counties

Ascension Parish, LA, Assumption Parish, LA, East Baton Rouge Parish, LA, East Feliciana Parish, LA, Iberia Parish, LA, Iberville Parish, LA, Jefferson Parish, LA, Lafourche Parish, LA, Livingston Parish, LA, Orleans Parish, LA, Plaquemines 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, Amite County, MS, Forrest County, MS, Hancock County, MS, Harrison County, MS, Jackson County, MS, Lamar County, MS, Marion County, MS, Pearl River County, MS, Pike County, MS, Stone County, MS, Walthall County, MS

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 00:00Z, 10.7 hours before the alert went out and 59 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: 1538 J/kg
Mixed-layer CIN: -5 J/kg
Mixed-layer LCL: 684 m above ground
0-6 km bulk shear: 17 kt
0-1 km storm-relative helicity: 18 m²/s²
0-3 km storm-relative helicity: 27 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.8

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
Oct 22, 4:57 AM CDT	Mesoscale Discussion	SPC	Bienville, Bossier, Caddo, Claiborne, De Soto, Jackson and 4 more	93 min
Oct 22, 9:29 AM CDT	Mesoscale Discussion	SPC	Harrison, Jackson	2 hr

Nearby

Mesoscale Discussions in Louisiana, 2017 Mesoscale Discussions in Mississippi, 2017 Every mesoscale discussion in 2017

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.