Alert archive / Arkansas / Mesoscale Discussions in 2021
Mesoscale Discussion 778
The Storm Prediction Center issued this mesoscale discussion at May 27, 2021, 8:17 PM CDT for 5 counties in Arkansas; LeFlore County, McCurtain County, Oklahoma. It was in force for 58 min.
The area
The outline as issued.
The facts
- Issued
- May 27, 2021, 8:17 PM CDT (01:17 UTC)
- Expired
- May 27, 2021, 9:15 PM CDT
- In force
- 58 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe thunderstorm watch 217
Counties Montgomery County, AR, Polk County, AR, Scott County, AR, Sebastian County, AR, Yell County, AR, LeFlore County, OK, McCurtain County, OK
The radar
The Western Arkansas radar (KSRX), 66 km from the middle of the area, began a volume at 01:19 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, 1.3 hours before the alert went out and 259 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
- 686 J/kg
- Mixed-layer CIN
- -59 J/kg
- Mixed-layer LCL
- 1424 m above ground
- 0-6 km bulk shear
- 30 kt
- 0-1 km storm-relative helicity
- 45 m²/s²
- 0-3 km storm-relative helicity
- 149 m²/s²
- Significant tornado parameter
- 0.1
- Supercell composite
- 1.6
The text
As transmitted.
767
ACUS11 KWNS 280118
SWOMCD
SPC MCD 280117
ARZ000-OKZ000-280215-
Mesoscale Discussion 0778
NWS Storm Prediction Center Norman OK
0817 PM CDT Thu May 27 2021
Areas affected...Parts of south central and southeastern Oklahoma
into adjacent portions of Arkansas
Concerning...Severe Thunderstorm Watch 217...
Valid 280117Z - 280215Z
The severe weather threat for Severe Thunderstorm Watch 217
continues.
SUMMARY...A more intense portion of a larger thunderstorm cluster
may pose continuing risk for potentially damaging wind gusts across
the Oklahoma/Arkansas border, between Fort Smith and De Queen, into
the Hot Springs vicinity by 10-11 PM CDT.
DISCUSSION...A cluster of stronger storms and southeastward surging
outflow, now southeast/east of the Muskogee and McAlester
vicinities, appears to have been supported during the past few hours
by a developing MCV. Westerly deep-layer mean flow may now be in
excess of 40 kt in a narrow corridor to the south of this feature,
contributing to a storm motion which probably will maintain
moderately strong southeasterly inflow of moist boundary-layer air
(characterized by CAPE in excess of 2000 J/kg) at least another
couple of hours. It appears that this will continue to be
accompanied by strong surface gusts approaching or exceeding severe
limits into areas near/northwest of Hot Springs, AR by 03-04Z.
..Kerr.. 05/28/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...LZK...SHV...TSA...
LAT...LON 35039490 35469443 34859303 34289386 34019454 34309516
34779537 35039490SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 27, 9:27 PM CDT | Mesoscale Discussion | SPC | Cleburne, Conway, Crawford, Faulkner, Franklin, Garland and 23 more | 93 min |
Nearby
Mesoscale Discussions in Arkansas, 2021Mesoscale Discussions in Oklahoma, 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.