Alert archive / Louisiana / Mesoscale Discussions in 2017

Mesoscale Discussion 81

January 20, 201713 parishes in Louisiana

The Storm Prediction Center issued this mesoscale discussion at Jan 20, 2017, 10:04 PM CST for 13 parishes in Louisiana. It was in force for 116 min.

The area

The outline as issued.

The facts

Issued: Jan 20, 2017, 10:04 PM CST (04:04 UTC)
Expired: Jan 21, 2017, 12:00 AM CST
In force: 116 min
Issued by: the Storm Prediction Center

Counties Acadia Parish, LA, Allen Parish, LA, Avoyelles Parish, LA, Calcasieu Parish, LA, Cameron Parish, LA, Evangeline Parish, LA, Iberia Parish, LA, Jefferson Davis Parish, LA, Lafayette Parish, LA, Saint Landry Parish, LA, Saint Martin Parish, LA, St. Mary Parish, LA, Vermilion Parish, LA

The radar

The Lake Charles radar (KLCH), 69 km from the middle of the area, began a volume at 04:08 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.

Tornado Watch 10Jan 20, 11:00 PM CST

The nearest sounding before it

Lake Charles Mun, LA (KLCH), launched 00:00Z, 4.1 hours before the alert went out and 68 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: 627 J/kg
Mixed-layer CIN: -37 J/kg
Mixed-layer LCL: 842 m above ground
0-6 km bulk shear: 47 kt
0-1 km storm-relative helicity: 68 m²/s²
0-3 km storm-relative helicity: 156 m²/s²
Significant tornado parameter: 0.2
Supercell composite: 0.9

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
Jan 20, 6:37 PM CST	Mesoscale Discussion	SPC	Acadia, Allen, Beauregard, Calcasieu, Cameron, Evangeline and 3 more	113 min
Jan 20, 7:32 PM CST	Tornado Watch	SPC	Acadia, Allen, Avoyelles, Beauregard, Calcasieu, Cameron and 9 more	6 hr
Jan 20, 10:44 PM CST	Mesoscale Discussion	SPC	Ascension, Assumption, East Baton Rouge, East Feliciana, Jefferson, Lafourche and 12 more	61 min
Jan 20, 11:00 PM CST	Tornado Watch	SPC	Ascension, Assumption, Concordia, East Baton Rouge, East Feliciana, Iberville and 17 more	8 hr
Jan 21, 1:41 AM CST	Mesoscale Discussion	SPC	Acadia, Avoyelles, Cameron, Evangeline, Iberia, Jefferson Davis and 5 more	64 min
Jan 21, 2:55 AM CST	Mesoscale Discussion	SPC	Ascension, Assumption, East Baton Rouge, East Feliciana, Iberville, Jefferson and 16 more	2 hr
Jan 21, 6:35 AM CST	Mesoscale Discussion	SPC	Jefferson, Lafourche, Orleans, Plaquemines, Saint Bernard, Saint Charles and 1 more	55 min
Jan 21, 2:33 PM CST	Mesoscale Discussion	SPC	Bienville, Bossier, Caddo, Claiborne, De Soto, Jackson and 8 more	2 hr
Jan 21, 2:34 PM CST	Mesoscale Discussion	SPC	Allen, Ascension, Avoyelles, Catahoula, Concordia, East Baton Rouge and 16 more	2 hr
Jan 21, 3:29 PM CST	Tornado Watch	SPC	Acadia, Ascension, Avoyelles, Catahoula, Concordia, East Baton Rouge and 22 more	6 hr
Jan 21, 3:41 PM CST	Tornado Watch	SPC	Bienville, Bossier, Caddo, Caldwell, Claiborne, De Soto and 11 more	7 hr
Jan 21, 5:32 PM CST	Mesoscale Discussion	SPC	Avoyelles, Bienville, Bossier, Caddo, Caldwell, Catahoula and 23 more	118 min

Nearby

Mesoscale Discussions in Louisiana, 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; radar from the NEXRAD Level II archive.