Alert archive / South Dakota / Mesoscale Discussions in 2021
Mesoscale Discussion 718
The Storm Prediction Center issued this mesoscale discussion at May 23, 2021, 8:22 PM CDT for 5 counties in North Dakota; 7 counties in South Dakota. It was in force for 53 min.
The area
The outline as issued.
The facts
- Issued
- May 23, 2021, 8:22 PM CDT (01:22 UTC)
- Expired
- May 23, 2021, 9:15 PM CDT
- In force
- 53 min
- Issued by
- the Storm Prediction Center
- Concerning
- Tornado watch 197
Counties Emmons County, ND, Grant County, ND, Morton County, ND, Oliver County, ND, Sioux County, ND, Campbell County, SD, Corson County, SD, Dewey County, SD, Potter County, SD, Stanley County, SD, Sully County, SD, Walworth County, SD
The radar
The Bismarck radar (KBIS), 131 km from the middle of the area, began a volume at 01:26 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
Bismarck Municip, ND (KBIS), launched 00:00Z, 1.4 hours before the alert went out and 131 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
- 36 J/kg
- Mixed-layer CIN
- -196 J/kg
- Mixed-layer LCL
- 806 m above ground
- 0-6 km bulk shear
- 35 kt
- 0-1 km storm-relative helicity
- 257 m²/s²
- 0-3 km storm-relative helicity
- 292 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.1
The text
As transmitted.
047 ACUS11 KWNS 240123 SWOMCD SPC MCD 240122 SDZ000-NDZ000-240215- Mesoscale Discussion 0718 NWS Storm Prediction Center Norman OK 0822 PM CDT Sun May 23 2021 Areas affected...Southwestern North Dakota...Northern/Central South Dakota Concerning...Tornado Watch 197... Valid 240122Z - 240215Z The severe weather threat for Tornado Watch 197 continues. SUMMARY...Severe threat continues across the northeastern portions of ww197. At this time it's not clear a new ww is warranted downstream. DISCUSSION...Squall line that matured across parts of western SD has since become less organized as it approaches the eastern edge of ww197. Even so, a substantial cold pool has developed in the wake of this linear MCS and its forward propagation will likely continue across central/north-central SD into south-central ND. Additionally, LLJ is forecast to strengthen across ND over the next few hours, and warm advection along/north of the advancing warm front may prove sufficient for additional strong development. Will continue to monitor adjacent portions of the Dakotas for possible ww, but current trends may not support a new watch. ..Darrow.. 05/24/2021 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...ABR...BIS...UNR... LAT...LON 44330114 47200241 47340088 45899993 44499965 44330114
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 23, 7:53 PM CDT | Mesoscale Discussion | SPC | Bennett | 67 min |
| May 23, 8:12 PM CDT | Severe Thunderstorm Watch | SPC | Mellette, Todd, Tripp | 5 hr |
| May 23, 9:56 PM CDT | Mesoscale Discussion | SPC | Tripp | 2 hr |
Nearby
Mesoscale Discussions in South Dakota, 2021Mesoscale Discussions in North Dakota, 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.