Alert archive / Louisiana / Mesoscale Discussions in 2015

Mesoscale Discussion 1909

October 31, 201524 parishes in Louisiana; 6 counties in Mississippi

The Storm Prediction Center issued this mesoscale discussion at Oct 31, 2015, 11:01 AM CDT for 24 parishes in Louisiana; 6 counties in Mississippi. It was in force for 89 min.

The area

The outline as issued.

The facts

Issued: Oct 31, 2015, 11:01 AM CDT (16:01 UTC)
Expired: Oct 31, 2015, 12:30 PM CDT
In force: 89 min
Issued by: the Storm Prediction Center
Chance of a watch: 60%

All 30 counties

Ascension Parish, LA, Assumption Parish, LA, Avoyelles Parish, LA, East Baton Rouge Parish, LA, East Feliciana Parish, LA, Iberia Parish, LA, Iberville Parish, LA, Lafourche Parish, LA, Livingston Parish, LA, Orleans Parish, LA, Pointe Coupee Parish, LA, Saint Charles Parish, LA, Saint Helena Parish, LA, Saint James Parish, LA, Saint John the Baptist Parish, LA, Saint Landry 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, Adams County, MS, Amite County, MS, Franklin County, MS, Pike County, MS, Walthall County, MS, Wilkinson County, MS

The watches that followed

Watches SPC issued over any of the same counties within four hours of this discussion.

Tornado Watch 528Oct 31, 11:40 AM CDT

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 12:00Z, 4.0 hours before the alert went out and 133 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: 1 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 847 m above ground
0-6 km bulk shear: 51 kt
0-1 km storm-relative helicity: 292 m²/s²
0-3 km storm-relative helicity: 361 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

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
Oct 31, 6:54 AM CDT	Tornado Watch	SPC	Acadia, Allen, Avoyelles, Beauregard, Calcasieu, Cameron and 10 more	5 hr
Oct 31, 10:03 AM CDT	Mesoscale Discussion	SPC	Acadia, Allen, Avoyelles, Beauregard, Calcasieu, Cameron and 8 more	57 min
Oct 31, 11:45 AM CDT	Tornado Watch	SPC	Acadia, Ascension, Assumption, Avoyelles, Cameron, Concordia and 27 more	8 hr
Oct 31, 1:35 PM CDT	Mesoscale Discussion	SPC	Acadia, Ascension, Assumption, Concordia, East Baton Rouge, East Feliciana and 22 more	55 min
Oct 31, 3:36 PM CDT	Mesoscale Discussion	SPC	Acadia, Ascension, Assumption, Concordia, East Baton Rouge, East Feliciana and 22 more	54 min
Oct 31, 5:42 PM CDT	Mesoscale Discussion	SPC	Acadia, Ascension, Assumption, Concordia, East Baton Rouge, East Feliciana and 22 more	93 min

Nearby

Mesoscale Discussions in Louisiana, 2015 Mesoscale Discussions in Mississippi, 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.