Alert archive / Minnesota / Mesoscale Discussions in 2021

Mesoscale Discussion 1635

August 28, 20218 counties in Minnesota; Brookings County, Lake County, Moody County, South Dakota

The Storm Prediction Center issued this mesoscale discussion at Aug 28, 2021, 7:44 PM CDT for 8 counties in Minnesota; Brookings County, Lake County, Moody County, South Dakota. It was in force for 91 min.

The area

The outline as issued.

The facts

Issued
Aug 28, 2021, 7:44 PM CDT (00:44 UTC)
Expired
Aug 28, 2021, 9:15 PM CDT
In force
91 min
Issued by
the Storm Prediction Center
Concerning
Tornado watch 469

Counties Cottonwood County, MN, Jackson County, MN, Lincoln County, MN, Lyon County, MN, Murray County, MN, Nobles County, MN, Pipestone County, MN, Rock County, MN, Brookings County, SD, Lake County, SD, Moody County, SD

The radar

The Sioux Falls radar (KFSD), 75 km from the middle of the area, began a volume at 00:48 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, 0.7 hours before the alert went out and 192 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-pSkew-T log-p diagram, Aberdeen, SD at 00:00Z on 2021-08-29Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 143 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Aberdeen, SD at 00:00Z on 2021-08-29The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -15 square meters per square second.1939587897Sfc1 km3 km6 km9 kmRMLM
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
143 J/kg
Mixed-layer CIN
-122 J/kg
Mixed-layer LCL
1242 m above ground
0-6 km bulk shear
71 kt
0-1 km storm-relative helicity
-15 m²/s²
0-3 km storm-relative helicity
268 m²/s²
Significant tornado parameter
-0.0
Supercell composite
-0.2

Open this sounding in Storm Lab

The text

As transmitted.

897 
ACUS11 KWNS 290044
SWOMCD
SPC MCD 290044 
MNZ000-IAZ000-SDZ000-290215-

Mesoscale Discussion 1635
NWS Storm Prediction Center Norman OK
0744 PM CDT Sat Aug 28 2021

Areas affected...Southwestern Minnesota...southeastern South Dakota

Concerning...Tornado Watch 469...

Valid 290044Z - 290215Z

The severe weather threat for Tornado Watch 469 continues.

SUMMARY...The threat for tornadoes has decreased in WW 469.
Thermodynamic and wind shear profiles will still favor a few
supercell structures capable of large hail and damaging winds.

DISCUSSION...Storms that developed along the surface boundary have
moved into cooler air from earlier convection. These storms will
still be capable of large hail and perhaps damaging winds given the
deep-layer shear and modestly steep mid-level lapse rates sampled by
the 00Z ABR/OAX soundings. The tornado threat has decreased,
however, due to storm interference and stable near-surface air.

..Wendt.. 08/29/2021

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

ATTN...WFO...MPX...DMX...FSD...ABR...

LAT...LON   44189737 44199713 44559709 44549646 44629642 44639563
            44239558 44199512 44139508 44109487 43499483 43509644
            43849646 43859737 44189737

Nearby

Mesoscale Discussions in Minnesota, 2021Mesoscale 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.