Alert archive / Arkansas / Mesoscale Discussions in 2021
Mesoscale Discussion 868
The Storm Prediction Center issued this mesoscale discussion at Jun 7, 2021, 2:16 PM CDT for 14 counties in Arkansas. It was in force for 119 min.
The area
The outline as issued.
The facts
- Issued
- Jun 7, 2021, 2:16 PM CDT (19:16 UTC)
- Expired
- Jun 7, 2021, 4:15 PM CDT
- In force
- 119 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe thunderstorm watch 242
Counties Clark County, AR, Dallas County, AR, Garland County, AR, Grant County, AR, Hempstead County, AR, Hot Spring County, AR, Howard County, AR, Montgomery County, AR, Nevada County, AR, Ouachita County, AR, Pike County, AR, Polk County, AR, Saline County, AR, Sevier County, AR
The radar
The Western Arkansas radar (KSRX), 136 km from the middle of the area, began a volume at 19:17 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 12:00Z, 7.3 hours before the alert went out and 191 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
- 2401 J/kg
- Mixed-layer CIN
- -18 J/kg
- Mixed-layer LCL
- 563 m above ground
- 0-6 km bulk shear
- 25 kt
- 0-1 km storm-relative helicity
- 64 m²/s²
- 0-3 km storm-relative helicity
- 123 m²/s²
- Significant tornado parameter
- 0.4
- Supercell composite
- 2.1
The text
As transmitted.
049
ACUS11 KWNS 071916
SWOMCD
SPC MCD 071916
ARZ000-OKZ000-072115-
Mesoscale Discussion 0868
NWS Storm Prediction Center Norman OK
0216 PM CDT Mon Jun 07 2021
Areas affected...parts of southwest and central AR...far southeast
OK
Concerning...Severe Thunderstorm Watch 242...
Valid 071916Z - 072115Z
The severe weather threat for Severe Thunderstorm Watch 242
continues.
SUMMARY...Several supercells exhibiting weak rotation will probably
persist this afternoon within a moist and adequately sheared
environment for low-level mesocyclones. A tornado risk may develop
and perhaps be the sole risk with these storms.
DISCUSSION...Single-site 88D imagery shows several supercells across
southwest and southern AR ahead of an MCV located over north-central
TX. Forecast hodographs show limited flow (at or below 30 kt)
through the troposphere but east-southeasterly surface flow veering
to 30-kt southwesterly 700 mb flow, is resulting in around 150 m2/s2
effective SRH. Surface conditions show temperatures in the mid to
upper 70s deg F with dewpoints in the lower 70s in the vicinity of a
modifying outflow boundary. The RAP forecast soundings are showing
a too-cool bias of 2 to 3 deg C at the surface. When modifying
these soundings for current observations, moderate buoyancy
(1000-2000 J/kg MLCAPE) is depicted. Given the seemingly marginal
but adequate low-level shear and moist boundary layer, it is
plausible several low-level mesocyclones will pose an isolated risk
for a tornado or two this afternoon.
..Smith.. 06/07/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...LZK...SHV...TSA...
LAT...LON 34259477 34749429 34789232 33949234 33559264 33889475
34259477SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jun 7, 12:32 PM CDT | Severe Thunderstorm Watch | SPC | Arkansas, Bradley, Calhoun, Clark, Cleveland, Columbia and 21 more | 6 hr |
| Jun 7, 3:08 PM CDT | Mesoscale Discussion | SPC | Ashley, Bradley, Columbia, Lafayette, Union | 2 hr |
| Jun 7, 5:09 PM CDT | Severe Thunderstorm Watch | SPC | Ashley, Chicot | 3 hr |
| Jun 7, 5:23 PM CDT | Mesoscale Discussion | SPC | Ashley, Bradley, Calhoun, Chicot, Cleveland, Dallas and 5 more | 67 min |
Nearby
Mesoscale 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.