Alert archive / Louisiana / Mesoscale Discussions in 2021

Mesoscale Discussion 289

March 27, 2021Bienville Parish, Louisiana; Panola County, Texas

The Storm Prediction Center issued this mesoscale discussion at Mar 27, 2021, 7:44 PM CDT for Bienville Parish, Louisiana; Panola County, Texas. It was in force for 61 min.

The area

The outline as issued.

The facts

Issued
Mar 27, 2021, 7:44 PM CDT (00:44 UTC)
Expired
Mar 27, 2021, 8:45 PM CDT
In force
61 min
Issued by
the Storm Prediction Center
Concerning
Tornado watch 60

Counties Bienville Parish, LA, Panola County, TX

The radar

The Shreveport radar (KSHV), 23 km from the middle of the area, began a volume at 00:45 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

Shreveport, LA (KSHV), launched 00:00Z, 0.7 hours before the alert went out and 28 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, Shreveport, LA at 00:00Z on 2021-03-28Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1297 joules per kilogram.LCLLFCEL10008507005003002001001 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, Shreveport, LA at 00:00Z on 2021-03-28The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 163 square meters per square second.1939587897Sfc1 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
1297 J/kg
Mixed-layer CIN
-41 J/kg
Mixed-layer LCL
953 m above ground
0-6 km bulk shear
45 kt
0-1 km storm-relative helicity
163 m²/s²
0-3 km storm-relative helicity
217 m²/s²
Significant tornado parameter
1.6
Supercell composite
8.1

Open this sounding in Storm Lab

The text

As transmitted.

809 
ACUS11 KWNS 280045
SWOMCD
SPC MCD 280044 
LAZ000-TXZ000-280145-

Mesoscale Discussion 0289
NWS Storm Prediction Center Norman OK
0744 PM CDT Sat Mar 27 2021

Areas affected...northeast Texas into northwest Louisiana

Concerning...Tornado Watch 60...

Valid 280044Z - 280145Z

The severe weather threat for Tornado Watch 60 continues.

SUMMARY...A supercell producing a strong tornado may persist for
another hour or so as it moves into northwest Louisiana.

DISCUSSION...A tornadic supercell now over Panola County TX has a
history of tornadoes, likely strong, with VROT up to 70 kt noted.
Although cycling down has been noted recently, this long-lived
supercell remains in a favorable environment for tornadoes, with 0-1
SRH over 200 m2/s2, increasing to nearly 300 m2/s2 on VWP, and
within a very moist air mass. The 00Z SHV sounding shows around 2100
J/kg MUCAPE, with a minor capping inversion just above 700 mb.

..Jewell/Grams.. 03/28/2021

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

ATTN...WFO...SHV...

LAT...LON   32089446 32219447 32319434 32689314 32569290 32379282
            32109366 32069411 32029428 32089446

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Mar 27, 9:01 PM CDTTornado WatchSPCEast Carroll, Morehouse, West Carroll7 hr
Mar 27, 10:30 PM CDTMesoscale DiscussionSPCBienville, Bossier, Caddo, Claiborne, De Soto, Jackson and 4 more2 hr

Nearby

Mesoscale Discussions in Louisiana, 2021Mesoscale Discussions in Texas, 2021Every 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.