Alert archive / Louisiana / Mesoscale Discussions in 2015

Mesoscale Discussion 1889

October 25, 201510 parishes in Louisiana; Hancock County, Harrison County, Jackson County, Mississippi

The Storm Prediction Center issued this mesoscale discussion at Oct 25, 2015, 10:15 PM CDT for 10 parishes in Louisiana; Hancock County, Harrison County, Jackson County, Mississippi. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Oct 25, 2015, 10:15 PM CDT (03:15 UTC)
Expired: Oct 26, 2015, 12:15 AM CDT
In force: 2 hr
Issued by: the Storm Prediction Center

Counties Jefferson Parish, LA, Lafourche Parish, LA, Orleans Parish, LA, Plaquemines Parish, LA, Saint Bernard Parish, LA, Saint Charles Parish, LA, Saint James Parish, LA, Saint John the Baptist Parish, LA, Saint Tammany Parish, LA, Terrebonne Parish, LA, Hancock County, MS, Harrison County, MS, Jackson County, MS

The watches that followed

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

Tornado Watch 522Oct 26, 2:05 AM CDT

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 00:00Z, 3.3 hours before the alert went out and 119 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: 318 J/kg
Mixed-layer CIN: 0 J/kg
Mixed-layer LCL: 488 m above ground
0-6 km bulk shear: 64 kt
0-1 km storm-relative helicity: 468 m²/s²
0-3 km storm-relative helicity: 554 m²/s²
Significant tornado parameter: 0.8
Supercell composite: 3.6

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, 7:12 PM CDT	Tornado Watch	SPC	Jefferson, Lafourche, Orleans, Plaquemines, Saint Bernard, Saint Charles and 3 more	7 hr
Oct 26, 1:32 AM CDT	Mesoscale Discussion	SPC	Saint Bernard	118 min
Oct 26, 2:05 AM CDT	Tornado Watch	SPC	Saint Bernard	7 hr
Oct 25, 7:53 PM CDT	Mesoscale Discussion	SPC	George, Jackson	3 hr
Oct 26, 7:32 AM CDT	Mesoscale Discussion	SPC	George, Jackson	118 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.