Alert archive / Louisiana / Mesoscale Discussions in 2016

Mesoscale Discussion 473

April 27, 201625 parishes in Louisiana; Adams County, Wilkinson County, Mississippi; Jefferson County, Newton County, Orange County, Texas

The Storm Prediction Center issued this mesoscale discussion at Apr 27, 2016, 7:30 AM CDT for 25 parishes in Louisiana; Adams County, Wilkinson County, Mississippi; Jefferson County, Newton County, Orange County, Texas. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Apr 27, 2016, 7:30 AM CDT (12:30 UTC)
Expired: Apr 27, 2016, 9:30 AM CDT
In force: 2 hr
Issued by: the Storm Prediction Center

All 30 counties

Acadia Parish, LA, Allen Parish, LA, Avoyelles Parish, LA, Beauregard Parish, LA, Calcasieu Parish, LA, Caldwell Parish, LA, Cameron Parish, LA, Catahoula Parish, LA, Concordia Parish, LA, Evangeline Parish, LA, Franklin Parish, LA, Grant Parish, LA, Jefferson Davis Parish, LA, Lafayette Parish, LA, LaSalle Parish, LA, Natchitoches Parish, LA, Pointe Coupee Parish, LA, Rapides Parish, LA, Sabine Parish, LA, Saint Landry Parish, LA, Tensas Parish, LA, Vermilion Parish, LA, Vernon Parish, LA, West Feliciana Parish, LA, Winn Parish, LA, Adams County, MS, Wilkinson County, MS, Jefferson County, TX, Newton County, TX, Orange County, TX

The radar

The Lake Charles radar (KLCH), 27 km from the middle of the area, began a volume at 12:29 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 115Apr 27, 7:55 AM CDT

The nearest sounding before it

Lake Charles Mun, LA (KLCH), launched 12:00Z, 0.5 hours before the alert went out and 28 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: 1558 J/kg
Mixed-layer CIN: -190 J/kg
Mixed-layer LCL: 749 m above ground
0-6 km bulk shear: 33 kt
0-1 km storm-relative helicity: 217 m²/s²
0-3 km storm-relative helicity: 356 m²/s²
Significant tornado parameter: 0.1
Supercell composite: 4.3

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
Apr 26, 9:36 PM CDT	Mesoscale Discussion	SPC	Bossier, Caddo	114 min
Apr 26, 10:21 PM CDT	Severe Thunderstorm Watch	SPC	Bossier, Caddo, De Soto, Red River, Sabine, Webster	9 hr
Apr 27, 1:35 AM CDT	Mesoscale Discussion	SPC	Bienville, Bossier, Caddo, Claiborne, De Soto, Lincoln and 3 more	115 min
Apr 27, 4:28 AM CDT	Mesoscale Discussion	SPC	Beauregard, Natchitoches, Red River, Sabine, Vernon	92 min
Apr 27, 4:56 AM CDT	Severe Thunderstorm Watch	SPC	Allen, Beauregard, Calcasieu, Cameron, De Soto, Evangeline and 9 more	5 hr
Apr 27, 7:54 AM CDT	Severe Thunderstorm Watch	SPC	Acadia, Ascension, Assumption, Avoyelles, Catahoula, Concordia and 29 more	7 hr
Apr 27, 1:34 PM CDT	Mesoscale Discussion	SPC	Attala, Calhoun, Chickasaw, Choctaw, Clarke, Clay and 32 more	2 hr
Apr 27, 3:28 PM CDT	Mesoscale Discussion	SPC	Tishomingo	2 hr
Apr 26, 8:52 PM CDT	Mesoscale Discussion	SPC	Bosque, Brown, Callahan, Clay, Coleman, Collin and 34 more	53 min

Nearby

Mesoscale Discussions in Louisiana, 2016 Mesoscale Discussions in Texas, 2016 Mesoscale Discussions in Mississippi, 2016 Every mesoscale discussion in 2016

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.