Alert archive / Nebraska / Mesoscale Discussions in 2021

Mesoscale Discussion 1070

June 23, 202131 counties in Nebraska; 4 counties in South Dakota

The Storm Prediction Center issued this mesoscale discussion at Jun 23, 2021, 6:13 PM CDT for 31 counties in Nebraska; 4 counties in South Dakota. It was in force for 92 min.

The area

The outline as issued.

The facts

Issued: Jun 23, 2021, 6:13 PM CDT (23:13 UTC)
Expired: Jun 23, 2021, 7:45 PM CDT
In force: 92 min
Issued by: the Storm Prediction Center
Concerning: Severe thunderstorm watch 306

All 35 counties

Antelope County, NE, Blaine County, NE, Boone County, NE, Boyd County, NE, Brown County, NE, Burt County, NE, Cedar County, NE, Colfax County, NE, Cuming County, NE, Custer County, NE, Dakota County, NE, Dixon County, NE, Dodge County, NE, Garfield County, NE, Greeley County, NE, Holt County, NE, Howard County, NE, Keya Paha County, NE, Knox County, NE, Loup County, NE, Madison County, NE, Nance County, NE, Pierce County, NE, Platte County, NE, Rock County, NE, Stanton County, NE, Thomas County, NE, Thurston County, NE, Valley County, NE, Wayne County, NE, Wheeler County, NE, Bon Homme County, SD, Clay County, SD, Union County, SD, Yankton County, SD

The radar

The North Platte radar (KLNX), 154 km from the middle of the area, began a volume at 23:17 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

N. Platte/Lee Bi, NE (KLBF), launched 12:00Z, 11.2 hours before the alert went out and 199 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: 211 J/kg
Mixed-layer CIN: -469 J/kg
Mixed-layer LCL: 2679 m above ground
0-6 km bulk shear: 32 kt
0-1 km storm-relative helicity: 32 m²/s²
0-3 km storm-relative helicity: 100 m²/s²
Significant tornado parameter: 0.0
Supercell composite: -0.0

Open this sounding in Storm Lab

The text

As transmitted.

992 
ACUS11 KWNS 232313
SWOMCD
SPC MCD 232313 
IAZ000-NEZ000-SDZ000-240045-

Mesoscale Discussion 1070
NWS Storm Prediction Center Norman OK
0613 PM CDT Wed Jun 23 2021

Areas affected...parts of central and eastern Nebraska and into far
southeastern South Dakota

Concerning...Severe Thunderstorm Watch 306...

Valid 232313Z - 240045Z

The severe weather threat for Severe Thunderstorm Watch 306
continues.

SUMMARY...Severe risk continues to increase locally over parts of
north-central Nebraska.  As convection shifts eastward -- spreading
out of the WW in the next 1-2 hours -- a new WW may be needed into
the northeastern Nebraska area.

DISCUSSION...Latest radar loop shows hints that storms may begin to
congeal across north-central Nebraska, as suggested by latest runs
of the HRRR and which seems reasonable given downstream instability
that is available.  As a south-southwesterly low-level jet develops
and then veers gradually through the evening, east-southeastward
propagation of the convection seems likely.

Presuming continued trends toward upscale growth, damaging wind
potential will likely become more widespread.  Otherwise, large hail
will remain possible, with baseball-sized hail reported earlier in
Keya Paha County.  As storms near the eastern edge of WW 306,
downstream watch issuance will likely be needed to encompass this
threat.

..Goss/Grams.. 06/23/2021

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

ATTN...WFO...FSD...OAX...GID...LBF...UNR...

LAT...LON   42760076 42930042 43149865 43039712 42799634 41829591
            41279704 41189854 41319996 41950078 42760076

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jun 22, 9:51 PM CDT	Mesoscale Discussion	SPC	Butler, Clay, Fillmore, Gage, Hamilton, Jefferson and 6 more	54 min
Jun 23, 3:51 PM CDT	Mesoscale Discussion	SPC	Arthur, Banner, Blaine, Box Butte, Brown, Cherry and 16 more	114 min
Jun 23, 4:40 PM CDT	Severe Thunderstorm Watch	SPC	Arthur, Blaine, Boyd, Brown, Cherry, Custer and 16 more	6 hr

Nearby

Mesoscale Discussions in Nebraska, 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.