Alert archive / South Dakota / Mesoscale Discussions in 2021
Mesoscale Discussion 1345
The Storm Prediction Center issued this mesoscale discussion at Jul 25, 2021, 2:28 PM MDT for 18 counties in South Dakota. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Jul 25, 2021, 2:28 PM MDT (20:28 UTC)
- Expired
- Jul 25, 2021, 4:30 PM MDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 20%
Counties Bennett County, SD, Brown County, SD, Buffalo County, SD, Edmunds County, SD, Faulk County, SD, Haakon County, SD, Hand County, SD, Hughes County, SD, Hyde County, SD, Jackson County, SD, Jones County, SD, Lyman County, SD, Mellette County, SD, Oglala Lakota County, SD, Potter County, SD, Spink County, SD, Stanley County, SD, Sully County, SD
The radar
The Rapid City radar (KUDX), 183 km from the middle of the area, began a volume at 20:28 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
Aberdeen, SD (KABR), launched 12:00Z, 8.5 hours before the alert went out and 184 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
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 2316 m above ground
- 0-6 km bulk shear
- 39 kt
- 0-1 km storm-relative helicity
- 89 m²/s²
- 0-3 km storm-relative helicity
- 98 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
161
ACUS11 KWNS 252028
SWOMCD
SPC MCD 252028
SDZ000-NEZ000-252230-
Mesoscale Discussion 1345
NWS Storm Prediction Center Norman OK
0328 PM CDT Sun Jul 25 2021
Areas affected...Portions of South Dakota
Concerning...Severe potential...Watch unlikely
Valid 252028Z - 252230Z
Probability of Watch Issuance...20 percent
SUMMARY...Isolated to widely-scattered storms are possible in South
Dakota this afternoon/early-evening. Storm coverage is not certain,
but a few supercell storms could pose a threat for damaging winds
and large hail. No watch is anticipated, but trends will be
monitored.
DISCUSSION...Cumulus development along a weak warm front from
southwestern into northeastern South Dakota is increasing this
afternoon. With continued heating, as well as an expected weak
increase in 850 mb winds into the boundary this evening, may promote
isolated to widely-scattered storm development. Regional 12Z
observed soundings sampled steep mid-level lapse rates with
low-level lapse rates also quite steep given strong heating. Modest
northwesterly flow aloft has contributed to around 35-50 kts of
effective shear roughly perpendicular to the boundary. Storms would
likely be supercellular in character. Damaging winds and large hail
would be possible. Large hail would have a higher probability in
northeast South Dakota where shear is stronger. There is a fair
amount of uncertainty as to the coverage of storms as overall
large-scale support is weak. Some guidance does develop a small
cluster this afternoon and evening, however. Should that occur, a
greater wind gust threat would also develop. While a watch is not
currently anticipated, trends will continue to be monitored.
..Wendt/Hart.. 07/25/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...FSD...ABR...LBF...UNR...CYS...
LAT...LON 43600296 44500168 45539946 45699841 45609797 45399765
44929781 43410002 42890180 42730256 43050317 43600296Nearby
Mesoscale Discussions in South 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.