Alert archive / Louisiana / Mesoscale Discussions in 2015

Mesoscale Discussion 1887

October 25, 20154 parishes in Louisiana

The Storm Prediction Center issued this mesoscale discussion at Oct 25, 2015, 6:21 PM CDT for 4 parishes in Louisiana. It was in force for 114 min.

The area

The outline as issued.

The facts

Issued: Oct 25, 2015, 6:21 PM CDT (23:21 UTC)
Expired: Oct 25, 2015, 8:15 PM CDT
In force: 114 min
Issued by: the Storm Prediction Center
Chance of a watch: 40%

Counties Jefferson Parish, LA, Lafourche Parish, LA, Plaquemines Parish, LA, Saint Charles Parish, LA

The watches that followed

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

Tornado Watch 521Oct 25, 7:10 PM CDT

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 12:00Z, 11.4 hours before the alert went out and 100 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: 21 J/kg
Mixed-layer CIN: -7 J/kg
Mixed-layer LCL: 538 m above ground
0-6 km bulk shear: 43 kt
0-1 km storm-relative helicity: 228 m²/s²
0-3 km storm-relative helicity: 260 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 25, 11:00 AM CDT	Mesoscale Discussion	SPC	Cameron, Iberia, Vermilion	3 hr
Oct 25, 11:36 AM CDT	Mesoscale Discussion	SPC	Ascension, Assumption, East Baton Rouge, Iberville, Jefferson, Lafourche and 13 more	114 min

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.