Mesoscale Discussion 1721

Issued

Aug 25, 2022, 2:50 PM MDT (20:50 UTC)

Expired

Aug 25, 2022, 5:15 PM MDT

In force

2 hr

Issued by

the Storm Prediction Center

Concerning

Severe potential...watch unlikely

Chance of a watch

20%

Counties Dawes County, NE, Custer County, SD, Fall River County, SD, Lawrence County, SD, Campbell County, WY, Converse County, WY, Crook County, WY, Johnson County, WY, Natrona County, WY, Niobrara County, WY, Weston County, WY

The Rapid City radar (KUDX), 190 km from the middle of the area, began a volume at 20:52 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.

804 
ACUS11 KWNS 252050
SWOMCD
SPC MCD 252050 
SDZ000-NEZ000-WYZ000-252315-

Mesoscale Discussion 1721
NWS Storm Prediction Center Norman OK
0350 PM CDT Thu Aug 25 2022

Areas affected...Northeast WY...Southwest SD...Northwest NE
Panhandle

Concerning...Severe potential...Watch unlikely 

Valid 252050Z - 252315Z

Probability of Watch Issuance...20 percent

SUMMARY...Storms capable of isolated hail and strong to potentially
severe wind gusts may gradually increase into the late afternoon and
early evening. Watch issuance is unlikely.

DISCUSSION...Thunderstorms have recently developed over the Black
Hills, with other convection gradually increasing to the west across
northeast WY, in conjunction with a midlevel shortwave trough
emerging from the northern Rockies. Cloudiness has inhibited diurnal
heating across parts of western SD and eastern WY, but relatively
moist low-level easterly flow is maintaining 50s to low 60s F
dewpoints across the region, allowing for modest MLCAPE in the
500-1000 J/kg range. Buoyancy may increase somewhat through the
afternoon, especially in areas where breaks in the clouds will allow
for some additional heating. 

Midlevel flow is not very strong, but low-level easterlies veering
to westerly aloft are resulting in effective shear of generally
20-30 kt, which could support a few stronger multicells capable of
isolated hail and strong wind gusts. Somewhat greater effective
shear may develop along the southern portion of the MCD area, in
association with a modest midlevel speed maximum along the southern
periphery of the compact shortwave. This speed maximum will spread
over a diffuse surface boundary, where somewhat greater surface
heating/destabilization has occurred, and could aid in the
development of a supercell or two from east-central WY into far
southwest SD and the northwest NE Panhandle, with a corresponding
risk of hail and strong/severe gusts. In general, coverage of the
severe risk is expected to remain too isolated for watch issuance.

..Dean/Bunting.. 08/25/2022

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

ATTN...WFO...UNR...CYS...BYZ...RIW...

LAT...LON   44550689 44670548 44770448 44550344 44090323 42820304
            42570317 42550418 42550530 42530604 42590648 42780688
            44550689

Mesoscale Discussions in Wyoming, 2022Mesoscale Discussions in South Dakota, 2022Mesoscale Discussions in Nebraska, 2022Every mesoscale discussion in 2022

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.