Alert archive / Louisiana / Mesoscale Discussions in 2021

Mesoscale Discussion 392

April 16, 20219 parishes in Louisiana; Newton County, Texas

The Storm Prediction Center issued this mesoscale discussion at Apr 16, 2021, 3:30 AM CDT for 9 parishes in Louisiana; Newton County, Texas. It was in force for 3 hr.

The area

The outline as issued.

The facts

Issued: Apr 16, 2021, 3:30 AM CDT (08:30 UTC)
Expired: Apr 16, 2021, 6:00 AM CDT
In force: 3 hr
Issued by: the Storm Prediction Center
Concerning: Severe potential...watch unlikely
Chance of a watch: 20%

Counties Acadia Parish, LA, Allen Parish, LA, Beauregard Parish, LA, Calcasieu Parish, LA, Evangeline Parish, LA, Jefferson Davis Parish, LA, Lafayette Parish, LA, Saint Landry Parish, LA, Saint Martin Parish, LA, Newton County, TX

The radar

The Lake Charles radar (KLCH), 55 km from the middle of the area, began a volume at 08:33 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 nearest sounding before it

Lake Charles Mun, LA (KLCH), launched 00:00Z, 8.5 hours before the alert went out and 55 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 952 m above ground
0-6 km bulk shear: 72 kt
0-1 km storm-relative helicity: 115 m²/s²
0-3 km storm-relative helicity: 210 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.2

Open this sounding in Storm Lab

The text

As transmitted.

144 
ACUS11 KWNS 160830
SWOMCD
SPC MCD 160830 
LAZ000-TXZ000-161100-

Mesoscale Discussion 0392
NWS Storm Prediction Center Norman OK
0330 AM CDT Fri Apr 16 2021

Areas affected...Southern Louisiana

Concerning...Severe potential...Watch unlikely 

Valid 160830Z - 161100Z

Probability of Watch Issuance...20 percent

SUMMARY...An isolated large hail and strong wind gusts potential
will exist early this morning across parts of southern Louisiana.
The threat is expected to remain localized and weather watch
issuance appears unlikely.

DISCUSSION...Over the last few hours, a small cluster of strong
thunderstorms has developed in the Sabine River Valley. This cluster
is being supported by large-scale ascent ahead of a shortwave trough
currently moving through the southern Plains. A short line segment
at the western end of the cluster appears to to be an organized
supercell but elevated in nature. This storm will continue to move
eastward along a gradient of instability, with the RAP analyzing
MUCAPE in the 500 to 1000 J/kg range. This combined with about 70 kt
of westerly flow in the mid-levels will support an isolated severe
threat over the next few hours. Large hail and strong wind gusts
will be possible. Storm coverage is expected to remain relatively
isolated. For this reason, weather watch issuance is not expected.

..Broyles/Grams.. 04/16/2021

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...LIX...LCH...

LAT...LON   31089330 31049361 30879385 30719395 30539401 30239390
            30159374 30019327 29889279 29799209 29799163 29989143
            30229136 30479139 30709166 30969231 31069294 31089330

Nearby

Mesoscale Discussions in Louisiana, 2021 Mesoscale Discussions in Texas, 2021 Every mesoscale discussion in 2021

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.