Alert archive / Louisiana / Mesoscale Discussions in 2005

Mesoscale Discussion 2256

September 23, 200511 parishes in Louisiana

The Storm Prediction Center issued this mesoscale discussion at Sep 23, 2005, 7:44 AM CDT for 11 parishes in Louisiana. It was in force for 91 min.

The area

The outline as issued.

The facts

Issued: Sep 23, 2005, 7:44 AM CDT (12:44 UTC)
Expired: Sep 23, 2005, 9:15 AM CDT
In force: 91 min
Issued by: the Storm Prediction Center

Counties Ascension Parish, LA, Assumption Parish, LA, Cameron Parish, LA, Iberville Parish, LA, Lafayette Parish, LA, Orleans Parish, LA, Saint Charles Parish, LA, Saint James Parish, LA, Saint John the Baptist Parish, LA, Saint Martin Parish, LA, Vermilion Parish, LA

The radar

The Lake Charles radar (KLCH), 116 km from the middle of the area, began a volume at 12:48 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 809Sep 23, 9:55 AM CDT

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 12:00Z, 0.7 hours before the alert went out and 225 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: 377 J/kg
Mixed-layer CIN: -53 J/kg
Mixed-layer LCL: 686 m above ground
0-6 km bulk shear: 20 kt
0-1 km storm-relative helicity: 268 m²/s²
0-3 km storm-relative helicity: 298 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
Sep 23, 9:55 AM CDT	Tornado Watch	SPC	Acadia, Ascension, Assumption, East Baton Rouge, Iberia, Iberville and 17 more	7 hr
Sep 23, 2:12 PM CDT	Mesoscale Discussion	SPC	Acadia, Ascension, Assumption, East Baton Rouge, Iberia, Iberville and 17 more	93 min
Sep 23, 4:33 PM CDT	Mesoscale Discussion	SPC	Acadia, Allen, Ascension, Assumption, Beauregard, Calcasieu and 28 more	87 min
Sep 23, 5:10 PM CDT	Tornado Watch	SPC	Acadia, Allen, Ascension, Assumption, Avoyelles, Beauregard and 30 more	13 hr

Nearby

Mesoscale Discussions in Louisiana, 2005 Every mesoscale discussion in 2005

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.