Alert archive / South Dakota / Mesoscale Discussions in 2018
Mesoscale Discussion 1349
The Storm Prediction Center issued this mesoscale discussion at Aug 23, 2018, 8:29 PM CDT for 5 counties in North Dakota; 14 counties in South Dakota. It was in force for 91 min.
The area
The outline as issued.
The facts
- Issued
- Aug 23, 2018, 8:29 PM CDT (01:29 UTC)
- Expired
- Aug 23, 2018, 10:00 PM CDT
- In force
- 91 min
- Issued by
- the Storm Prediction Center
Counties Dickey County, ND, Emmons County, ND, Logan County, ND, McIntosh County, ND, Sioux County, ND, Brown County, SD, Buffalo County, SD, Campbell County, SD, Edmunds County, SD, Faulk County, SD, Hand County, SD, Hughes County, SD, Hyde County, SD, Lyman County, SD, McPherson County, SD, Potter County, SD, Spink County, SD, Sully County, SD, Walworth County, SD
The radar
The Aberdeen radar (KABR), 106 km from the middle of the area, began a volume at 01:32 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 00:00Z, 1.5 hours before the alert went out and 104 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
- 1172 J/kg
- Mixed-layer CIN
- -108 J/kg
- Mixed-layer LCL
- 816 m above ground
- 0-6 km bulk shear
- 27 kt
- 0-1 km storm-relative helicity
- 178 m²/s²
- 0-3 km storm-relative helicity
- 227 m²/s²
- Significant tornado parameter
- 0.3
- Supercell composite
- 5.3
The text
As transmitted.
917
ACUS11 KWNS 240130
SWOMCD
SPC MCD 240129
SDZ000-NDZ000-240300-
Mesoscale Discussion 1349
NWS Storm Prediction Center Norman OK
0829 PM CDT Thu Aug 23 2018
Areas affected...Dakotas
Concerning...Severe Thunderstorm Watch 348...349...
Valid 240129Z - 240300Z
The severe weather threat for Severe Thunderstorm Watch 348, 349
continues.
SUMMARY...Severe threat will focus across the western part of WW348.
WW349 may be canceled soon.
DISCUSSION...Convection has struggled to progress east of 99w as air
mass across the eastern Dakotas is characterized by poor low-level
lapse rates, though seasonally moist with surface dew points in the
mid-upper 60s. 00z soundings across the High Plains from LBF to BIS
exhibit near-surface based buoyancy with substantial instability
beneath cold thermal trough. For these reasons convection continues
to regenerate along the western side of WW348 where parcels are less
restricted. Earlier storms that produced severe hail/wind across
south-central SD appear to be negatively influence by diurnal
cooling thus convection should primarily remain north of ww349 the
rest of this evening. Hail remains the main threat with
thunderstorms across mainly the western half of WW348.
..Darrow.. 08/24/2018
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...FSD...ABR...BIS...
LAT...LON 43879992 44950030 45920138 46750062 46349867 45429792
43849877 43879992SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 23, 11:32 PM CDT | Mesoscale Discussion | SPC | Dickey, Emmons, McIntosh, Ransom, Richland, Sargent | 58 min |
Nearby
Mesoscale Discussions in South Dakota, 2018Mesoscale Discussions in North Dakota, 2018Every mesoscale discussion in 2018
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.