Alert archive / Arkansas / Mesoscale Discussions in 2021
Mesoscale Discussion 773
The Storm Prediction Center issued this mesoscale discussion at May 27, 2021, 4:52 PM CDT for 53 counties in Arkansas. It was in force for 83 min.
The area
The outline as issued.
The facts
- Issued
- May 27, 2021, 4:52 PM CDT (21:52 UTC)
- Expired
- May 27, 2021, 6:15 PM CDT
- In force
- 83 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...severe thunderstorm watch likely
- Chance of a watch
- 80%
All 53 counties
Arkansas County, AR, Baxter County, AR, Benton County, AR, Boone County, AR, Carroll County, AR, Clark County, AR, Cleburne County, AR, Cleveland County, AR, Conway County, AR, Craighead County, AR, Crawford County, AR, Cross County, AR, Dallas County, AR, Faulkner County, AR, Franklin County, AR, Fulton County, AR, Garland County, AR, Grant County, AR, Hot Spring County, AR, Howard County, AR, Independence County, AR, Izard County, AR, Jackson County, AR, Jefferson County, AR, Johnson County, AR, Lawrence County, AR, Lincoln County, AR, Logan County, AR, Lonoke County, AR, Madison County, AR, Marion County, AR, Monroe County, AR, Montgomery County, AR, Newton County, AR, Perry County, AR, Pike County, AR, Poinsett County, AR, Pope County, AR, Prairie County, AR, Pulaski County, AR, Randolph County, AR, Saline County, AR, Scott County, AR, Searcy County, AR, Sebastian County, AR, Sharp County, AR, St. Francis County, AR, Stone County, AR, Van Buren County, AR, Washington County, AR, White County, AR, Woodruff County, AR, Yell County, AR
The radar
The Little Rock radar (KLZK), 56 km from the middle of the area, began a volume at 21:51 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, 9.9 hours before the alert went out and 213 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
- 295 J/kg
- Mixed-layer CIN
- -229 J/kg
- Mixed-layer LCL
- 964 m above ground
- 0-6 km bulk shear
- 42 kt
- 0-1 km storm-relative helicity
- 69 m²/s²
- 0-3 km storm-relative helicity
- 160 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.6
The text
As transmitted.
041
ACUS11 KWNS 272152
SWOMCD
SPC MCD 272152
ARZ000-MOZ000-OKZ000-272315-
Mesoscale Discussion 0773
NWS Storm Prediction Center Norman OK
0452 PM CDT Thu May 27 2021
Areas affected...much of central and northern Arkansas
Concerning...Severe potential...Severe Thunderstorm Watch likely
Valid 272152Z - 272315Z
Probability of Watch Issuance...80 percent
SUMMARY...Storm coverage and associated severe potential are
expected to increase over the next few hours, particularly with a
bowing segment approaching from northeast OK. A Severe Thunderstorm
Watch will be needed soon.
DISCUSSION...Several hours of persistent diurnal heating (evident
via visible satellite imagery) have boosted surface temperatures to
around 90F, per latest METAR observations. 70+ F dewpoints are in
place, overspread by 7-8.5 C/km low-level lapse rates which in turn
support 2500-3000 J/kg MLCAPE, despite modest mid-level
temperatures/lapse rates, as shown by 21Z mesoanalysis. Modest wind
speeds aloft are fostering 25-35 kts of effective bulk shear per
latest mesoanalysis/RAP forecast soundings, suggesting that some
organization will occur with storms moving in from eastern OK.
Latest KINX radar shows a loosely organized linear convective
segment just northeast of TUL, which is poised to propagate
southeast into the aforementioned strongly unstable airmass over the
next couple of hours. Given the steep low-level lapse rates and
strong instability, damaging-gust potential will persist with the
more organized storms moving into central AR, necessitating a Severe
Thunderstorm Watch. While damaging winds are expected to be the
primary threat with the approaching storms, modest surface-700 mb
veering with height (shown by KSRX VWPs) suggests that transient low
to mid-level rotation/supercell potential may accompany some of the
strongest, longest lasting storms. As such, a couple severe
hailstones and perhaps a tornado or two are also possible.
..Squitieri/Edwards.. 05/27/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...MEG...LZK...SGF...SHV...TSA...
LAT...LON 34029400 35479446 36079443 36479427 36509289 36529184
36479087 36019056 35099071 34419091 33959122 33749271
34029400SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 27, 11:04 AM CDT | Mesoscale Discussion | SPC | Baxter, Benton, Boone, Carroll, Cleburne, Crawford and 15 more | 86 min |
| May 27, 11:29 AM CDT | Mesoscale Discussion | SPC | Crawford | 61 min |
| May 27, 2:06 PM CDT | Mesoscale Discussion | SPC | Baxter, Boone, Clay, Cleburne, Conway, Craighead and 23 more | 84 min |
| May 27, 5:12 PM CDT | Severe Thunderstorm Watch | SPC | Arkansas, Baxter, Benton, Boone, Carroll, Clark and 41 more | 8 hr |
| May 27, 5:21 PM CDT | Mesoscale Discussion | SPC | Clay, Craighead, Greene, Mississippi | 114 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.