Alert archive / Louisiana / Mesoscale Discussions in 2021
Mesoscale Discussion 292
The Storm Prediction Center issued this mesoscale discussion at Mar 27, 2021, 10:30 PM CDT for Union County, Arkansas; 10 parishes in Louisiana; 5 counties in Texas. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Mar 27, 2021, 10:30 PM CDT (03:30 UTC)
- Expired
- Mar 28, 2021, 12:30 AM CDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Tornado watch 60
Counties Union County, AR, Bienville Parish, LA, Bossier Parish, LA, Caddo Parish, LA, Claiborne Parish, LA, De Soto Parish, LA, Jackson Parish, LA, Lincoln Parish, LA, Red River Parish, LA, Union Parish, LA, Webster Parish, LA, Cherokee County, TX, Nacogdoches County, TX, Panola County, TX, Rusk County, TX, Shelby County, TX
The radar
The Shreveport radar (KSHV), 32 km from the middle of the area, began a volume at 03:30 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, 3.5 hours before the alert went out and 38 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.
- 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
The text
As transmitted.
744
ACUS11 KWNS 280331
SWOMCD
SPC MCD 280330
LAZ000-ARZ000-TXZ000-280530-
Mesoscale Discussion 0292
NWS Storm Prediction Center Norman OK
1030 PM CDT Sat Mar 27 2021
Areas affected...northeast Texas into northern Louisiana
Concerning...Tornado Watch 60...
Valid 280330Z - 280530Z
The severe weather threat for Tornado Watch 60 continues.
SUMMARY...A threat of severe storms persist along the trailing line
of storms. A brief tornado is possible over the next 1-2 hours, with
a transition to mainly hail and wind.
DISCUSSION...Training storms persist from the LA/AR border
southwestward into northeast TX, just ahead of the approaching cold
front. The VWP from SHV shows pronounced veering of the low-level
winds, which is reducing SRH from there west. Therefore, while the
air mass remains moist and unstable, the tornado threat is lessening
with time. The greatest threat of a tornado appears to be over
northern/northeast LA where low level shear is greatest.
Strong, front-parallel deep shear will remain over the area, which
may support a few intensifying cells within this line. Hail will be
possible, along with isolated damaging wind gusts. Increasing
convergence with the cold front may also yield greater storm
coverage later tonight.
..Jewell.. 03/28/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...JAN...LZK...SHV...HGX...FWD...
LAT...LON 31719563 32659414 33329277 33299215 32789193 32349236
31809340 31439448 31479522 31489563 31719563SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Mar 27, 9:01 PM CDT | Tornado Watch | SPC | Ashley, Chicot, Crittenden, Lee, Phillips, St. Francis | 7 hr |
| Mar 27, 10:45 PM CDT | Mesoscale Discussion | SPC | Ashley, Chicot, Desha | 90 min |
| Mar 27, 7:44 PM CDT | Mesoscale Discussion | SPC | Bienville | 61 min |
Nearby
Mesoscale Discussions in Louisiana, 2021Mesoscale Discussions in Texas, 2021Mesoscale Discussions in Arkansas, 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.