Alert archive / Nebraska / Mesoscale Discussions in 2022

Mesoscale Discussion 1321

July 1, 2022Carter County, Montana; 12 counties in Nebraska; 10 counties in South Dakota

The Storm Prediction Center issued this mesoscale discussion at Jul 1, 2022, 7:01 PM MDT for Carter County, Montana; 12 counties in Nebraska; 10 counties in South Dakota. It was in force for 119 min.

The area

The outline as issued.

The facts

Issued: Jul 1, 2022, 7:01 PM MDT (01:01 UTC)
Expired: Jul 1, 2022, 9:00 PM MDT
In force: 119 min
Issued by: the Storm Prediction Center
Concerning: Severe thunderstorm watch 418

All 23 counties

Carter County, MT, Arthur County, NE, Box Butte County, NE, Cherry County, NE, Dawes County, NE, Deuel County, NE, Garden County, NE, Grant County, NE, Hooker County, NE, Keith County, NE, McPherson County, NE, Morrill County, NE, Sheridan County, NE, Bennett County, SD, Butte County, SD, Custer County, SD, Fall River County, SD, Harding County, SD, Jackson County, SD, Lawrence County, SD, Meade County, SD, Oglala Lakota County, SD, Pennington County, SD

The radar

The Rapid City radar (KUDX), 45 km from the middle of the area, began a volume at 01:04 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

Rapid City, SD (KUNR), launched 00:00Z, 1.0 hours before the alert went out and 38 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: 119 J/kg
Mixed-layer CIN: -140 J/kg
Mixed-layer LCL: 1469 m above ground
0-6 km bulk shear: 40 kt
0-1 km storm-relative helicity: 175 m²/s²
0-3 km storm-relative helicity: 91 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.3

Open this sounding in Storm Lab

The text

As transmitted.

042 
ACUS11 KWNS 020101
SWOMCD
SPC MCD 020101 
NEZ000-SDZ000-NDZ000-MTZ000-WYZ000-020300-

Mesoscale Discussion 1321
NWS Storm Prediction Center Norman OK
0801 PM CDT Fri Jul 01 2022

Areas affected...Far Southeast Montana...Western South
Dakota...Northwest Nebraska

Concerning...Severe Thunderstorm Watch 418...

Valid 020101Z - 020300Z

The severe weather threat for Severe Thunderstorm Watch 418
continues.

SUMMARY...A wind-damage and isolated large hail threat will likely
continue for a few more hours across parts of western South Dakota
and northwest Nebraska. An isolated severe threat may also persist
across far southeast Montana, where large hail will also be
possible. The severe threat should become more isolated as the 04Z
expiration of WW 418 approaches. Additional watch issuance is not
expected downstream.

DISCUSSION...The latest high-resolution radar from Rapid City, South
Dakota shows a line of strong thunderstorms from southwest South
Dakota into far northwest Nebraska. This line will continue to move
southeastward along a corridor of instability, where the RAP is
analyzing MLCAPE in the 500 to 1200 J/kg range. Additional storms
are located further northwest near the instability axis, across far
northwest South Dakota and far southeast Montana. Moderate
deep-layer shear and steep mid-level lapse rates, evident on RAP
forecast soundings, will continue to support a severe threat for two
to three more hours. Isolated supercells with large hail will be
possible. Wind damage may also accompany the stronger downdrafts. As
instability begins to decrease due to cooling boundary layer
temperatures, a gradual downtrend in the severe threat is expected
later this evening.

..Broyles.. 07/02/2022

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

ATTN...WFO...BIS...LBF...UNR...CYS...BYZ...

LAT...LON   41060219 41190288 41780364 42440368 43280373 44600424
            45610515 46000535 46250499 46010419 45760361 45510315
            45060258 44350173 43670109 42740065 41400067 41060219

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 2, 1:20 PM MDT	Mesoscale Discussion	SPC	Carter, Custer, Daniels, Dawson, Fallon, Garfield and 9 more	115 min
Jul 2, 2:20 PM MDT	Severe Thunderstorm Watch	SPC	Custer, Daniels, Dawson, Fallon, McCone, Prairie and 4 more	7 hr
Jul 2, 3:43 PM MDT	Mesoscale Discussion	SPC	Broadwater, Cascade, Chouteau, Deer Lodge, Fergus, Garfield and 10 more	3 hr
Jul 2, 4:20 PM MDT	Mesoscale Discussion	SPC	Dawson, Fallon, Richland, Roosevelt, Sheridan, Wibaux	115 min

Nearby

Mesoscale Discussions in Nebraska, 2022 Mesoscale Discussions in South Dakota, 2022 Mesoscale Discussions in Montana, 2022 Every mesoscale discussion in 2022

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.