Alert archive / Louisiana / Mesoscale Discussions in 2015

Mesoscale Discussion 353

April 18, 201511 parishes in Louisiana

The Storm Prediction Center issued this mesoscale discussion at Apr 18, 2015, 1:31 AM CDT for 11 parishes in Louisiana. It was in force for 59 min.

The area

The outline as issued.

The facts

Issued: Apr 18, 2015, 1:31 AM CDT (06:31 UTC)
Expired: Apr 18, 2015, 2:30 AM CDT
In force: 59 min
Issued by: the Storm Prediction Center

Counties Acadia Parish, LA, Assumption Parish, LA, Calcasieu Parish, LA, Cameron Parish, LA, Iberia Parish, LA, Iberville Parish, LA, Jefferson Davis Parish, LA, Lafayette Parish, LA, Saint Martin Parish, LA, St. Mary Parish, LA, Vermilion Parish, LA

The radar

The Lake Charles radar (KLCH), 57 km from the middle of the area, began a volume at 06:32 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 nearest sounding before it

Lake Charles Mun, LA (KLCH), launched 00:00Z, 6.5 hours before the alert went out and 56 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: 1637 J/kg
Mixed-layer CIN: -5 J/kg
Mixed-layer LCL: 835 m above ground
0-6 km bulk shear: 38 kt
0-1 km storm-relative helicity: 10 m²/s²
0-3 km storm-relative helicity: 136 m²/s²
Significant tornado parameter: 0.1
Supercell composite: 0.7

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.

Issued	Product	Office	Counties	Lasted
Apr 17, 9:13 PM CDT	Severe Thunderstorm Watch	SPC	Acadia, Calcasieu, Cameron, Iberia, Jefferson Davis, Lafayette and 3 more	5 hr
Apr 17, 11:31 PM CDT	Mesoscale Discussion	SPC	Calcasieu, Cameron, Iberia, Jefferson Davis, Vermilion	59 min
Apr 18, 6:17 PM CDT	Mesoscale Discussion	SPC	Avoyelles, Catahoula, Concordia, Grant, LaSalle, Rapides and 2 more	2 hr

Nearby

Mesoscale Discussions in Louisiana, 2015 Every mesoscale discussion in 2015

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.