Alert archive / Louisiana / Mesoscale Discussions in 2020

Mesoscale Discussion 1589

August 27, 202010 parishes in Louisiana

The Storm Prediction Center issued this mesoscale discussion at Aug 27, 2020, 1:41 AM CDT for 10 parishes in Louisiana. It was in force for 3 hr.

The area

The outline as issued.

The facts

Issued
Aug 27, 2020, 1:41 AM CDT (06:41 UTC)
Expired
Aug 27, 2020, 4:45 AM CDT
In force
3 hr
Issued by
the Storm Prediction Center
Concerning
Tornado watch 453

Counties Acadia Parish, LA, Allen Parish, LA, Evangeline Parish, LA, Iberia Parish, LA, Jefferson Davis Parish, LA, Lafayette Parish, LA, Saint Landry Parish, LA, Saint Martin Parish, LA, St. Mary Parish, LA, Vermilion Parish, LA

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 00:00Z, 6.7 hours before the alert went out and 262 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-pSkew-T log-p diagram, Slidell Radar S, LA at 00:00Z on 2020-08-27Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1989 joules per kilogram.LCLEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Slidell Radar S, LA at 00:00Z on 2020-08-27The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 179 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
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
1989 J/kg
Mixed-layer CIN
-1 J/kg
Mixed-layer LCL
724 m above ground
0-6 km bulk shear
29 kt
0-1 km storm-relative helicity
179 m²/s²
0-3 km storm-relative helicity
200 m²/s²
Significant tornado parameter
0.0
Supercell composite
6.3

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.

IssuedProductOfficeCountiesLasted
Aug 26, 7:47 PM CDTMesoscale DiscussionSPCAcadia, Allen, Ascension, Assumption, Avoyelles, Beauregard and 26 more118 min
Aug 26, 9:03 PM CDTTornado WatchSPCAcadia, Allen, Ascension, Assumption, Avoyelles, Beauregard and 32 more11 hr
Aug 26, 11:00 PM CDTMesoscale DiscussionSPCAcadia, Beauregard, Calcasieu, Cameron, Iberia, Jefferson Davis and 2 more2 hr
Aug 27, 6:36 AM CDTMesoscale DiscussionSPCCaldwell, Catahoula, Concordia, East Baton Rouge, East Carroll, East Feliciana and 16 more114 min
Aug 27, 7:47 AM CDTTornado WatchSPCAscension, Assumption, Avoyelles, Bienville, Caldwell, Catahoula and 44 more8 hr
Aug 27, 11:10 AM CDTMesoscale DiscussionSPCSaint Tammany, Washington2 hr
Aug 27, 2:41 PM CDTMesoscale DiscussionSPCJefferson, Plaquemines, Saint Bernard94 min

Nearby

Mesoscale Discussions in Louisiana, 2020Every mesoscale discussion in 2020

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.