Alert archive / Minnesota / Mesoscale Discussions in 2021

Mesoscale Discussion 1816

October 9, 202115 counties in Minnesota; 4 counties in South Dakota

The Storm Prediction Center issued this mesoscale discussion at Oct 9, 2021, 6:00 PM CDT for 15 counties in Minnesota; 4 counties in South Dakota. It was in force for 90 min.

The area

The outline as issued.

The facts

Issued: Oct 9, 2021, 6:00 PM CDT (23:00 UTC)
Expired: Oct 9, 2021, 7:30 PM CDT
In force: 90 min
Issued by: the Storm Prediction Center
Concerning: Severe thunderstorm watch 514

Counties Big Stone County, MN, Chippewa County, MN, Douglas County, MN, Grant County, MN, Kandiyohi County, MN, Lac qui Parle County, MN, Morrison County, MN, Otter Tail County, MN, Pope County, MN, Stearns County, MN, Stevens County, MN, Swift County, MN, Todd County, MN, Traverse County, MN, Wadena County, MN, Codington County, SD, Deuel County, SD, Grant County, SD, Roberts County, SD

The radar

The Aberdeen radar (KABR), 191 km from the middle of the area, began a volume at 23:02 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.

Severe Thunderstorm Watch 515Oct 9, 6:35 PM CDT

The nearest sounding before it

Aberdeen, SD (KABR), launched 12:00Z, 11.0 hours before the alert went out and 210 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.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 4 J/kg
Mixed-layer CIN: -89 J/kg
Mixed-layer LCL: 713 m above ground
0-6 km bulk shear: 37 kt
0-1 km storm-relative helicity: 97 m²/s²
0-3 km storm-relative helicity: 200 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.1

Open this sounding in Storm Lab

The text

As transmitted.

114 
ACUS11 KWNS 092300
SWOMCD
SPC MCD 092300 
MNZ000-SDZ000-NDZ000-100030-

Mesoscale Discussion 1816
NWS Storm Prediction Center Norman OK
0600 PM CDT Sat Oct 09 2021

Areas affected...Southeast ND...Eastern SD...Southwestern and
central MN

Concerning...Severe Thunderstorm Watch 514...

Valid 092300Z - 100030Z

The severe weather threat for Severe Thunderstorm Watch 514
continues.

SUMMARY...Damaging wind threat will spread into southwestern
Minnesota over the next few hours. New severe thunderstorm watch
will likely be warranted by 10/00z.

DISCUSSION...Squall line has matured and is advancing east-northeast
at roughly 30-35kt across the northeastern half of ww514. Latest
diagnostic data suggests surface low is located over southeast SD,
very near the southern updraft along the squall line over Kingsbury
County. Focused LLJ is shifting downstream across southwestern MN
and this will encourage a well-organized MCS to propagate east of
the current watch in the next 1-2 hours. Damaging winds have been
reported along the leading edge of the squall line, and should
continue for the next several hours as significant buoyancy resides
ahead of this activity across southern/central MN. While damaging
winds are the primary severe risk, especially given the linear storm
mode, wind profiles and radar data suggest one or two brief
tornadoes along the QLCS as it propagates east-northeast.

..Darrow.. 10/09/2021

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

ATTN...WFO...DLH...MPX...FGF...FSD...ABR...

LAT...LON   45999742 46859514 46129393 45099494 44369708 45999742

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Oct 9, 12:04 PM CDT	Mesoscale Discussion	SPC	Lincoln	2 hr
Oct 9, 2:56 PM CDT	Severe Thunderstorm Watch	SPC	Big Stone, Traverse, Wilkin	7 hr
Oct 9, 6:34 PM CDT	Severe Thunderstorm Watch	SPC	Becker, Cass, Chippewa, Crow Wing, Douglas, Grant and 14 more	7 hr
Oct 9, 3:40 PM CDT	Mesoscale Discussion	SPC	Beadle, Clark, Codington, Deuel, Hamlin, Kingsbury	95 min
Oct 9, 5:50 PM CDT	Mesoscale Discussion	SPC	Haakon, Jackson, Jones, Mellette, Stanley, Todd	55 min

Nearby

Mesoscale Discussions in Minnesota, 2021 Mesoscale Discussions in South Dakota, 2021 Every 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.