Alert archive / Arkansas / Mesoscale Discussions in 2021
Mesoscale Discussion 1941
The Storm Prediction Center issued this mesoscale discussion at Nov 11, 2021, 1:19 AM CST for 16 counties in Arkansas; 11 parishes in Louisiana. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Nov 11, 2021, 1:19 AM CST (07:19 UTC)
- Expired
- Nov 11, 2021, 3:45 AM CST
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 5%
All 27 counties
Bradley County, AR, Calhoun County, AR, Clark County, AR, Cleveland County, AR, Columbia County, AR, Dallas County, AR, Garland County, AR, Grant County, AR, Hot Spring County, AR, Jefferson County, AR, Lafayette County, AR, Nevada County, AR, Ouachita County, AR, Pulaski County, AR, Saline County, AR, 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, Winn Parish, LA
The radar
The Little Rock radar (KLZK), 149 km from the middle of the area, began a volume at 07:19 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, 7.3 hours before the alert went out and 150 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
- 158 J/kg
- Mixed-layer CIN
- -89 J/kg
- Mixed-layer LCL
- 968 m above ground
- 0-6 km bulk shear
- 41 kt
- 0-1 km storm-relative helicity
- 198 m²/s²
- 0-3 km storm-relative helicity
- 302 m²/s²
- Significant tornado parameter
- 0.1
- Supercell composite
- 0.3
The text
As transmitted.
568
ACUS11 KWNS 110720
SWOMCD
SPC MCD 110719
ARZ000-LAZ000-TXZ000-110945-
Mesoscale Discussion 1941
NWS Storm Prediction Center Norman OK
0119 AM CST Thu Nov 11 2021
Areas affected...South-central Arkansas...Northwest Louisiana
Concerning...Severe potential...Watch unlikely
Valid 110719Z - 110945Z
Probability of Watch Issuance...5 percent
SUMMARY...An isolated wind-damage threat along with a potential for
a brief tornado should persist for a couple hours from south-central
Arkansas into northwest Louisiana. The threat is not expected to be
great enough for weather watch issuance.
DISCUSSION...The latest radar imagery from Shreveport shows a linear
MCS currently moving across far northwest Arkansas extending
southwestward into northeast Texas. The line of storms is located
along the eastern edge of a corridor of maximized low-level
moisture, with the RAP estimating MLCAPE in the 500 to 750 J/kg
range. In spite of the weak instability near the front, moderate
deep-layer shear is present with 40 knots of 0-6km shear evident on
the Shreveport WSR-88D VWP. This combined with about 35 knots of
flow near 850 mb may be enough for an isolated wind-damage threat or
potential for a brief tornado early this morning. The QLCS is
expected to weaken as it shifts further east into Arkansas and
Louisiana.
..Broyles/Grams.. 11/11/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...JAN...LZK...SHV...
LAT...LON 32859215 33849182 34529186 34829210 34899276 34679325
34369335 33459357 32939382 31899407 31819270 32859215Nearby
Mesoscale Discussions in Arkansas, 2021Mesoscale Discussions in Louisiana, 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.