Alert archive / Louisiana / Mesoscale Discussions in 2021
Mesoscale Discussion 883
The Storm Prediction Center issued this mesoscale discussion at Jun 8, 2021, 11:17 AM CDT for 4 counties in Arkansas; 20 parishes in Louisiana; Issaquena County, Sharkey County, Washington County, Mississippi. It was in force for 118 min.
The area
The outline as issued.
The facts
- Issued
- Jun 8, 2021, 11:17 AM CDT (16:17 UTC)
- Expired
- Jun 8, 2021, 1:15 PM CDT
- In force
- 118 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch possible
- Chance of a watch
- 60%
All 27 counties
Ashley County, AR, Chicot County, AR, Columbia County, AR, Union County, AR, Bienville Parish, LA, Bossier Parish, LA, Caddo Parish, LA, Caldwell Parish, LA, Claiborne Parish, LA, De Soto Parish, LA, East Carroll Parish, LA, Franklin Parish, LA, Jackson Parish, LA, Lincoln Parish, LA, Madison Parish, LA, Morehouse Parish, LA, Natchitoches Parish, LA, Ouachita Parish, LA, Red River Parish, LA, Richland Parish, LA, Union Parish, LA, Webster Parish, LA, West Carroll Parish, LA, Winn Parish, LA, Issaquena County, MS, Sharkey County, MS, Washington County, MS
The radar
The Shreveport radar (KSHV), 172 km from the middle of the area, began a volume at 16:21 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.
The nearest sounding before it
Shreveport, LA (KSHV), launched 12:00Z, 4.3 hours before the alert went out and 163 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
- 1621 J/kg
- Mixed-layer CIN
- -10 J/kg
- Mixed-layer LCL
- 580 m above ground
- 0-6 km bulk shear
- 21 kt
- 0-1 km storm-relative helicity
- 106 m²/s²
- 0-3 km storm-relative helicity
- 218 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 3.1
The text
As transmitted.
523
ACUS11 KWNS 081618
SWOMCD
SPC MCD 081617
MSZ000-ARZ000-LAZ000-081815-
Mesoscale Discussion 0883
NWS Storm Prediction Center Norman OK
1117 AM CDT Tue Jun 08 2021
Areas affected...northern LA...far southern AR...west-central MS
Concerning...Severe potential...Watch possible
Valid 081617Z - 081815Z
Probability of Watch Issuance...60 percent
SUMMARY...The risk for damaging surface gusts will probably increase
this afternoon coincident with a small-scale bowing complex forecast
to move from west to east across northern LA.
DISCUSSION...Surface analysis at 11am CDT shows temperatures have
warmed into the mid 80s deg F with mid 70s dewpoints across northern
LA to the south of a stationary west to east oriented outflow
boundary over southeast AR into northern MS. The Shreveport, LA 88D
VAD is showing generally 30-40 kt southwesterly flow in the 1-4 km
AGL layer. Model guidance maintains a ribbon of 30-kt southwesterly
850 mb flow across northern LA this afternoon. Given the very
unstable airmass (2500-3000 J/kg MLCAPE) forecast by models this
afternoon, it seems plausible a focused corridor for wind damage
potential will evolve as the east TX cluster moves east this
afternoon.
..Smith/Guyer.. 06/08/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...JAN...LZK...SHV...
LAT...LON 32179103 31589372 32369403 32899381 33359321 33539113
33169058 32679061 32239102 32179103SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jun 7, 7:16 PM CDT | Mesoscale Discussion | SPC | Arkansas, Crittenden, Cross, Lee, Lonoke, Monroe and 4 more | 59 min |
| Jun 8, 12:42 PM CDT | Severe Thunderstorm Watch | SPC | Arkansas, Ashley, Bradley, Calhoun, Chicot, Cleveland and 9 more | 6 hr |
| Jun 8, 10:11 AM CDT | Mesoscale Discussion | SPC | Bossier, Caddo | 64 min |
| Jun 8, 2:47 PM CDT | Mesoscale Discussion | SPC | Caldwell, East Carroll, Franklin, Madison, Richland, West Carroll | 118 min |
Nearby
Mesoscale Discussions in Louisiana, 2021Mesoscale Discussions in Arkansas, 2021Mesoscale Discussions in Mississippi, 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.