Alert archive / South Dakota / Mesoscale Discussions in 2018
Mesoscale Discussion 902
The Storm Prediction Center issued this mesoscale discussion at Jun 26, 2018, 11:52 PM CDT for 21 counties in South Dakota. It was in force for 113 min.
The area
The outline as issued.
The facts
- Issued
- Jun 26, 2018, 11:52 PM CDT (04:52 UTC)
- Expired
- Jun 27, 2018, 1:45 AM CDT
- In force
- 113 min
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 80%
All 21 counties
Brule County, SD, Buffalo County, SD, Campbell County, SD, Corson County, SD, Dewey County, SD, Haakon County, SD, Hughes County, SD, Hyde County, SD, Jackson County, SD, Jones County, SD, Lyman County, SD, Meade County, SD, Mellette County, SD, Perkins County, SD, Potter County, SD, Stanley County, SD, Sully County, SD, Todd County, SD, Tripp County, SD, Walworth County, SD, Ziebach County, SD
The radar
The Rapid City radar (KUDX), 136 km from the middle of the area, began a volume at 04:53 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 watches that followed
Watches SPC issued over any of the same counties within four hours of this discussion.
The nearest sounding before it
Rapid City, SD (KRAP), launched 00:00Z, 4.9 hours before the alert went out and 141 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
- 1573 J/kg
- Mixed-layer CIN
- -153 J/kg
- Mixed-layer LCL
- 2012 m above ground
- 0-6 km bulk shear
- 52 kt
- 0-1 km storm-relative helicity
- 112 m²/s²
- 0-3 km storm-relative helicity
- 202 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 3.3
The text
As transmitted.
042
ACUS11 KWNS 270453
SWOMCD
SPC MCD 270452
SDZ000-NDZ000-270645-
Mesoscale Discussion 0902
NWS Storm Prediction Center Norman OK
1152 PM CDT Tue Jun 26 2018
Areas affected...Parts of western and central SD
Concerning...Severe potential...Watch likely
Valid 270452Z - 270645Z
Probability of Watch Issuance...80 percent
SUMMARY...An isolated severe risk in the short term is expected to
increase in coverage, with storms growing upscale into a
forward-propagating convective complex across central South Dakota
tonight with threat for damaging winds and hail. A severe
thunderstorm watch is likely for parts of South Dakota.
DISCUSSION...Since 03-0330Z, mosaic radar imagery showed an increase
in storms and overall intensities along a surface boundary extending
from southwest ND into extreme southeast MT, with this broken band
of storms tracking to the southeast. Forcing for ascent attendant
to a progressive shortwave trough, now moving into the western
Dakotas, appears to be aiding in this convective development, and
should result in strengthening southerly low-level winds across the
central High Plains into western and central SD through tonight to
early Wednesday morning. A residual reservoir of very strong
instability residing across western and central SD will be fed into
the southern extent of the storm activity by the strengthening
low-level jet. A 50-kt westerly midlevel jet accompanying the
progressive shortwave trough will maintain strong effective bulk
shear with vectors generally sustaining a linear structure through
the overnight period. These factors support greater forecast
confidence in a scenario for an MCS producing a severe-weather
threat across parts of western and central SD through tonight.
..Peters/Edwards.. 06/27/2018
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...FSD...ABR...BIS...UNR...
LAT...LON 45620331 45830260 45950047 45869974 44549916 43989899
43409921 43070018 43140124 43320188 43890263 44450307
45620331SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jun 26, 9:05 PM CDT | Mesoscale Discussion | SPC | Harding, Perkins | 115 min |
| Jun 27, 12:12 AM CDT | Severe Thunderstorm Watch | SPC | Buffalo, Butte, Campbell, Corson, Dewey, Edmunds and 17 more | 9 hr |
| Jun 27, 2:18 AM CDT | Mesoscale Discussion | SPC | Buffalo, Butte, Campbell, Corson, Dewey, Edmunds and 17 more | 87 min |
| Jun 27, 4:18 AM CDT | Mesoscale Discussion | SPC | Aurora, Brule, Buffalo, Charles Mix, Davison, Douglas and 10 more | 87 min |
| Jun 27, 4:34 AM CDT | Severe Thunderstorm Watch | SPC | Aurora, Beadle, Bon Homme, Brule, Charles Mix, Davison and 10 more | 5 hr |
| Jun 27, 7:25 AM CDT | Mesoscale Discussion | SPC | Aurora, Beadle, Bon Homme, Brule, Buffalo, Charles Mix and 18 more | 95 min |
Nearby
Mesoscale Discussions in South 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.