Alert archive / Louisiana / Mesoscale Discussions in 2017

Mesoscale Discussion 605

April 30, 201726 parishes in Louisiana; 4 counties in Mississippi; 8 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at Apr 30, 2017, 1:14 AM CDT for 26 parishes in Louisiana; 4 counties in Mississippi; 8 counties in Texas. It was in force for 91 min.

The area

The outline as issued.

The facts

Issued: Apr 30, 2017, 1:14 AM CDT (06:14 UTC)
Expired: Apr 30, 2017, 2:45 AM CDT
In force: 91 min
Issued by: the Storm Prediction Center
Chance of a watch: 60%

All 38 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, Iberia Parish, LA, Jefferson Davis Parish, LA, Lafayette Parish, LA, LaSalle Parish, LA, Madison Parish, LA, Pointe Coupee Parish, LA, Rapides Parish, LA, Richland Parish, LA, Saint Landry Parish, LA, Saint Martin Parish, LA, Tensas Parish, LA, Vermilion Parish, LA, Vernon Parish, LA, West Baton Rouge Parish, LA, West Feliciana Parish, LA, Adams County, MS, Claiborne County, MS, Jefferson County, MS, Wilkinson County, MS, Chambers County, TX, Hardin County, TX, Jasper County, TX, Jefferson County, TX, Liberty County, TX, Newton County, TX, Orange County, TX, Tyler County, TX

The radar

The Ft Polk radar (KPOE), 55 km from the middle of the area, began a volume at 06:18 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 180Apr 30, 1:50 AM CDT

The nearest sounding before it

Lake Charles Mun, LA (KLCH), launched 00:00Z, 6.2 hours before the alert went out and 73 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: 3254 J/kg
Mixed-layer CIN: -63 J/kg
Mixed-layer LCL: 602 m above ground
0-6 km bulk shear: 37 kt
0-1 km storm-relative helicity: 198 m²/s²
0-3 km storm-relative helicity: 251 m²/s²
Significant tornado parameter: 3.4
Supercell composite: 26.7

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 29, 9:38 PM CDT	Mesoscale Discussion	SPC	Bossier, Caddo, De Soto, Sabine, Webster	67 min
Apr 29, 10:23 PM CDT	Severe Thunderstorm Watch	SPC	Bienville, Bossier, Caddo, Caldwell, Claiborne, De Soto and 11 more	8 hr
Apr 29, 11:37 PM CDT	Mesoscale Discussion	SPC	Bienville, Bossier, Caddo, Claiborne, De Soto, Lincoln and 5 more	53 min
Apr 30, 1:49 AM CDT	Tornado Watch	SPC	Acadia, Allen, Avoyelles, Beauregard, Calcasieu, Cameron and 21 more	7 hr
Apr 30, 3:36 AM CDT	Mesoscale Discussion	SPC	Caldwell, Grant, Jackson, LaSalle, Lincoln, Natchitoches and 3 more	84 min
Apr 30, 5:41 AM CDT	Mesoscale Discussion	SPC	Union	64 min
Apr 30, 6:12 AM CDT	Mesoscale Discussion	SPC	Acadia, Avoyelles, Concordia, East Baton Rouge, East Carroll, East Feliciana and 16 more	93 min
Apr 30, 6:59 AM CDT	Mesoscale Discussion	SPC	Ascension, Assumption, East Baton Rouge, East Feliciana, Jefferson, Lafourche and 12 more	2 hr
Apr 30, 7:32 AM CDT	Tornado Watch	SPC	Ascension, Assumption, East Baton Rouge, East Feliciana, Iberville, Jefferson and 14 more	7 hr
Apr 30, 12:54 AM CDT	Mesoscale Discussion	SPC	Bolivar, Coahoma, DeSoto, Panola, Quitman, Sunflower and 3 more	96 min
Apr 30, 1:10 AM CDT	Severe Thunderstorm Watch	SPC	DeSoto, Tunica	6 hr
Apr 30, 2:58 AM CDT	Mesoscale Discussion	SPC	DeSoto, Marshall, Tate, Tunica	92 min
Apr 30, 10:06 AM CDT	Mesoscale Discussion	SPC	Chickasaw, Itawamba, Lee, Monroe, Pontotoc, Prentiss and 2 more	84 min
Apr 30, 10:36 AM CDT	Tornado Watch	SPC	Alcorn, Benton, Calhoun, Chickasaw, Itawamba, Lafayette and 9 more	8 hr
Apr 29, 7:34 PM CDT	Mesoscale Discussion	SPC	Anderson, Delta, Fannin, Franklin, Freestone, Henderson and 11 more	56 min
Apr 29, 8:57 PM CDT	Mesoscale Discussion	SPC	Bastrop, Brazos, Burleson, Caldwell, Fayette, Gonzales and 11 more	63 min
Apr 30, 1:25 AM CDT	Mesoscale Discussion	SPC	Dallam, Sherman	6 hr

Nearby

Mesoscale Discussions in Louisiana, 2017 Mesoscale Discussions in Texas, 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; radar from the NEXRAD Level II archive.