Alert archive / Oklahoma / Mesoscale Discussions in 2021

Mesoscale Discussion 1694

September 4, 2021Benton County, Carroll County, Arkansas; 5 counties in Missouri; 10 counties in Oklahoma

The Storm Prediction Center issued this mesoscale discussion at Sep 4, 2021, 3:23 PM CDT for Benton County, Carroll County, Arkansas; 5 counties in Missouri; 10 counties in Oklahoma. It was in force for 3 hr.

The area

The outline as issued.

The facts

Issued: Sep 4, 2021, 3:23 PM CDT (20:23 UTC)
Expired: Sep 4, 2021, 6:00 PM CDT
In force: 3 hr
Issued by: the Storm Prediction Center
Concerning: Severe potential...watch unlikely
Chance of a watch: 20%

Counties Benton County, AR, Carroll County, AR, Barry County, MO, Lawrence County, MO, McDonald County, MO, Newton County, MO, Stone County, MO, Cherokee County, OK, Craig County, OK, Creek County, OK, Delaware County, OK, Mayes County, OK, Ottawa County, OK, Pawnee County, OK, Rogers County, OK, Tulsa County, OK, Wagoner County, OK

The radar

The Tulsa radar (KINX), 48 km from the middle of the area, began a volume at 20:26 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

Springfield, MO (KSGF), launched 12:00Z, 8.4 hours before the alert went out and 129 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.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 980 J/kg
Mixed-layer CIN: -11 J/kg
Mixed-layer LCL: 653 m above ground
0-6 km bulk shear: 32 kt
0-1 km storm-relative helicity: 0 m²/s²
0-3 km storm-relative helicity: 32 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

707 
ACUS11 KWNS 042023
SWOMCD
SPC MCD 042023 
MOZ000-ARZ000-OKZ000-KSZ000-042300-

Mesoscale Discussion 1694
NWS Storm Prediction Center Norman OK
0323 PM CDT Sat Sep 04 2021

Areas affected...Southwestern Missouri...Northeastern Oklahoma...and
far Northwestern Arkansas

Concerning...Severe potential...Watch unlikely 

Valid 042023Z - 042300Z

Probability of Watch Issuance...20 percent

SUMMARY...Scattered thunderstorms are expected to develop this
afternoon along/near a cold front across the area.  While isolated
severe wind gusts are possible with the strongest storms, the
marginal setup/environment will likely preclude the necessity of a
watch.

DISCUSSION...Low-level convergence along the surface boundary should
be sufficient for initiation of scattered thunderstorms across the
region this afternoon.  Diurnal heating south of this boundary has
resulted in steep low-level lapse rates (~8 C/km) and a moderately
unstable airmass (~1500 J/kg of MLCAPE).  While flow is not
particularly strong aloft (~30 knots per regional VWPs), the
effective-layer bulk shear (30-35 knots) should be sufficient to
support organized updrafts.  Perhaps the biggest limiting factor for
severe potential is the relatively warm air aloft (per warm layers
noted above 500 mb in the 18Z OUN and LMN soundings), which will
likely limit updraft strength and longevity.  Nevertheless, if
strong updrafts can be sustained, the environment will be supportive
of isolated damaging downburst winds from the strongest storms.

..Jirak/Bunting.. 09/04/2021

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...LZK...SGF...TSA...OUN...

LAT...LON   36259687 36759559 37129451 37199376 36879304 36429327
            36159383 35919460 35739544 35639636 36039686 36259687

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Sep 4, 2:20 PM CDT	Mesoscale Discussion	SPC	Carter, Dent, Iron, Madison, Reynolds, Shannon and 1 more	115 min

Nearby

Mesoscale Discussions in Oklahoma, 2021 Mesoscale Discussions in Missouri, 2021 Mesoscale Discussions in Arkansas, 2021 Every 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.