Alert archive / Arkansas / Mesoscale Discussions in 2021
Mesoscale Discussion 206
The Storm Prediction Center issued this mesoscale discussion at Mar 17, 2021, 1:18 PM CDT for 4 states. It was in force for 57 min.
The area
The outline as issued.
The facts
- Issued
- Mar 17, 2021, 1:18 PM CDT (18:18 UTC)
- Expired
- Mar 17, 2021, 2:15 PM CDT
- In force
- 57 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch likely
- Chance of a watch
- 80%
All 46 counties
Benton County, AR, Boone County, AR, Carroll County, AR, Clark County, AR, Crawford County, AR, Franklin County, AR, Garland County, AR, Hempstead County, AR, Hot Spring County, AR, Howard County, AR, Johnson County, AR, Little River County, AR, Logan County, AR, Madison County, AR, Miller County, AR, Montgomery County, AR, Nevada County, AR, Newton County, AR, Ouachita County, AR, Perry County, AR, Pike County, AR, Polk County, AR, Pope County, AR, Scott County, AR, Sebastian County, AR, Sevier County, AR, Washington County, AR, Yell County, AR, Cherokee County, KS, Barry County, MO, Jasper County, MO, Lawrence County, MO, McDonald County, MO, Newton County, MO, Stone County, MO, Taney County, MO, Adair County, OK, Cherokee County, OK, Craig County, OK, Delaware County, OK, LeFlore County, OK, Mayes County, OK, Ottawa County, OK, Rogers County, OK, Sequoyah County, OK, Wagoner County, OK
The radar
The Western Arkansas radar (KSRX), 24 km from the middle of the area, began a volume at 18:18 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
Springfield, MO (KSGF), launched 12:00Z, 6.3 hours before the alert went out and 190 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
- 102 J/kg
- Mixed-layer CIN
- -235 J/kg
- Mixed-layer LCL
- 956 m above ground
- 0-6 km bulk shear
- 58 kt
- 0-1 km storm-relative helicity
- 220 m²/s²
- 0-3 km storm-relative helicity
- 236 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 1.9
The text
As transmitted.
033
ACUS11 KWNS 171818
SWOMCD
SPC MCD 171818
ARZ000-MOZ000-TXZ000-OKZ000-KSZ000-171915-
Mesoscale Discussion 0206
NWS Storm Prediction Center Norman OK
0118 PM CDT Wed Mar 17 2021
Areas affected...Northeast Oklahoma...western Arkansas...and
southwest Missouri.
Concerning...Severe potential...Watch likely
Valid 171818Z - 171915Z
Probability of Watch Issuance...80 percent
SUMMARY...An arcing line of supercells/line segments is likely from
southern Arkansas to northeast Oklahoma this afternoon.
DISCUSSION...The morning convection and associated cloud shield has
moved out of western Arkansas and eastern Oklahoma which has allowed
surface heating ahead of the surface cold front and near the surface
low currently located in northeast Oklahoma. The 18Z KLZK RAOB had a
stable near surface layer, but modifying this sounding for low 70s
temperatures and low 60s dewpoints which are currently present in
northwest Arkansas and northeast Oklahoma yields around 500 to 750
J/kg MLCAPE and a nearly uncapped profile. Early convective
development in northeast Oklahoma suggests this remaining inhibition
has likely eroded as cooler air aloft continues to spread overhead.
Therefore, several low-topped supercells are expected to develop
along the cold front within the hour. Overall, weak instability will
be the primary limiting factor for a greater severe weather threat,
but effective SRH around 150 to 200 m2/s2 per SPC mesoanalysis and
increased low-level vorticity in close proximity to the surface low
may lead to a locally higher tornado/landspout threat. In addition
to the tornado threat, there will be a threat for damaging winds and
large hail given the strong low-level flow and cool temperatures
aloft.
..Bentley/Grams.. 03/17/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...LZK...SGF...SHV...TSA...ICT...
LAT...LON 33369430 34029469 35339494 35849531 35919575 36469578
37059543 37219471 37239413 37009357 36599294 35659269
34669274 34039273 33559289 33379338 33239374 33369430SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Mar 17, 12:45 AM CDT | Mesoscale Discussion | SPC | Benton, Washington | 90 min |
| Mar 17, 1:32 AM CDT | Mesoscale Discussion | SPC | Ashley, Bradley, Calhoun, Clark, Cleveland, Columbia and 27 more | 118 min |
| Mar 17, 4:04 AM CDT | Mesoscale Discussion | SPC | Columbia, Hempstead, Lafayette, Little River, Miller, Sevier | 86 min |
| Mar 17, 4:37 AM CDT | Severe Thunderstorm Watch | SPC | Hempstead, Howard, Lafayette, Little River, Miller, Nevada and 1 more | 5 hr |
| Mar 17, 5:34 AM CDT | Mesoscale Discussion | SPC | Arkansas, Crittenden, Cross, Desha, Lee, Lincoln and 3 more | 86 min |
| Mar 17, 5:53 AM CDT | Tornado Watch | SPC | Arkansas, Bradley, Cleveland, Crittenden, Desha, Drew and 8 more | 7 hr |
| Mar 17, 6:40 AM CDT | Mesoscale Discussion | SPC | Calhoun, Clark, Columbia, Crawford, Dallas, Franklin and 19 more | 95 min |
| Mar 17, 7:38 AM CDT | Mesoscale Discussion | SPC | Crittenden, Lee, Monroe, Phillips, St. Francis | 67 min |
| Mar 17, 7:47 AM CDT | Tornado Watch | SPC | Calhoun, Clark, Conway, Dallas, Faulkner, Garland and 15 more | 5 hr |
| Mar 17, 8:43 AM CDT | Tornado Watch | SPC | Columbia, Union | 4 hr |
| Mar 17, 12:15 PM CDT | Mesoscale Discussion | SPC | Ashley, Chicot, Desha, Drew, Phillips | 90 min |
| Mar 17, 12:57 PM CDT | Tornado Watch | SPC | Ashley, Chicot, Lee, Phillips | 6 hr |
| Mar 17, 2:00 PM CDT | Tornado Watch | SPC | Benton, Boone, Carroll, Crawford, Franklin, Johnson and 12 more | 7 hr |
| Mar 17, 2:56 PM CDT | Mesoscale Discussion | SPC | Ashley, Chicot, Desha, Drew | 94 min |
| Mar 17, 3:37 PM CDT | Mesoscale Discussion | SPC | Baxter, Benton, Boone, Carroll, Crawford, Franklin and 5 more | 83 min |
| Mar 17, 6:09 PM CDT | Mesoscale Discussion | SPC | Crittenden, Cross | 66 min |
| Mar 16, 7:49 PM CDT | Severe Thunderstorm Watch | SPC | Cowley, Harper, Sumner | 7 hr |
| Mar 17, 1:54 AM CDT | Severe Thunderstorm Watch | SPC | Allen, Anderson, Bourbon, Butler, Chautauqua, Cherokee and 10 more | 6 hr |
| Mar 17, 4:38 AM CDT | Mesoscale Discussion | SPC | Morton, Stevens | 6 hr |
| Mar 17, 5:18 AM CDT | Mesoscale Discussion | SPC | Bourbon, Cherokee, Crawford, Labette, Linn, Montgomery and 1 more | 87 min |
| Mar 17, 8:51 AM CDT | Mesoscale Discussion | SPC | Audrain, Boone, Callaway, Camden, Christian, Cole and 35 more | 84 min |
| Mar 17, 1:56 AM CDT | Mesoscale Discussion | SPC | Blaine, Custer, Garfield, Kay, Kingfisher, Logan and 3 more | 64 min |
Nearby
Mesoscale Discussions in Arkansas, 2021Mesoscale Discussions in Oklahoma, 2021Mesoscale Discussions in Missouri, 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.