Alert archive / Nebraska / Mesoscale Discussions in 2021

Mesoscale Discussion 1218

July 9, 20214 counties in Colorado; 4 counties in Kansas; 41 counties in Nebraska

The Storm Prediction Center issued this mesoscale discussion at Jul 9, 2021, 5:16 PM MDT for 4 counties in Colorado; 4 counties in Kansas; 41 counties in Nebraska. It was in force for 119 min.

The area

The outline as issued.

The facts

Issued: Jul 9, 2021, 5:16 PM MDT (23:16 UTC)
Expired: Jul 9, 2021, 7:15 PM MDT
In force: 119 min
Issued by: the Storm Prediction Center
Concerning: Severe thunderstorm watch 356

All 49 counties

Logan County, CO, Phillips County, CO, Sedgwick County, CO, Yuma County, CO, Cheyenne County, KS, Decatur County, KS, Rawlins County, KS, Sherman County, KS, Arthur County, NE, Banner County, NE, Blaine County, NE, Box Butte County, NE, Brown County, NE, Buffalo County, NE, Chase County, NE, Cheyenne County, NE, Custer County, NE, Dawes County, NE, Dawson County, NE, Deuel County, NE, Dundy County, NE, Frontier County, NE, Furnas County, NE, Garden County, NE, Garfield County, NE, Gosper County, NE, Grant County, NE, Greeley County, NE, Hayes County, NE, Hitchcock County, NE, Hooker County, NE, Howard County, NE, Keith County, NE, Kimball County, NE, Lincoln County, NE, Logan County, NE, Loup County, NE, McPherson County, NE, Morrill County, NE, Perkins County, NE, Phelps County, NE, Red Willow County, NE, Scotts Bluff County, NE, Sheridan County, NE, Sherman County, NE, Sioux County, NE, Thomas County, NE, Valley County, NE, Wheeler County, NE

The radar

The Goodland radar (KGLD), 162 km from the middle of the area, began a volume at 23:18 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

N. Platte/Lee Bi, NE (KLBF), launched 12:00Z, 11.3 hours before the alert went out and 109 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: 93 J/kg
Mixed-layer CIN: -824 J/kg
Mixed-layer LCL: 1724 m above ground
0-6 km bulk shear: 46 kt
0-1 km storm-relative helicity: -13 m²/s²
0-3 km storm-relative helicity: 24 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

611 
ACUS11 KWNS 092317
SWOMCD
SPC MCD 092316 
NEZ000-KSZ000-COZ000-WYZ000-100115-

Mesoscale Discussion 1218
NWS Storm Prediction Center Norman OK
0616 PM CDT Fri Jul 09 2021

Areas affected...Western/central Nebraska...northeast
Colorado...northwest Kansas

Concerning...Severe Thunderstorm Watch 356...

Valid 092316Z - 100115Z

The severe weather threat for Severe Thunderstorm Watch 356
continues.

SUMMARY...Storm coverage is expected to increase due to increasing
large-scale lift across the central Plains this evening. Large hail
severe wind gusts will remain possible. MCS development is most
likely from the Nebraska Panhandle into central Nebraska, which
would bring a greater severe wind gust threat.

DISCUSSION...Storm coverage has remained isolated across WW 356
likely on account of shortwave ridging aloft. With time, an
approaching shortwave moving southeastward out of Montana as well as
an increasing low-level jet in western Kansas into southwestern
Nebraska will increase large-scale lift. This should lead to
increasing storm coverage in portions of WW 356. CAM guidance has
continued to differ on the exact evolution of the current activity
in western Nebraska/northeast Colorado.

The ongoing supercell in northeast Colorado continues to move toward
better moisture and will be situated near the the low-level jet axis
this evening in western Kansas. This activity could grow upscale and
move southeastward. The downstream environment has seen dewpoint mix
out into the low 60s F making it uncertain as to how far such
activity will progress.

The more likely scenario, based on current observations, is that
storms in the Nebraska Panhandle will continue to grow upscale and
organize along a weak cold front situated north of I-80. Better
mid-level ascent from the approaching shortwave gives greater
confidence in this occurring within the next 2-4 hours.

..Wendt.. 07/09/2021

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

ATTN...WFO...OAX...GID...LBF...GLD...BOU...CYS...

LAT...LON   41340383 41650412 42440424 42790318 42409944 41769809
            40599887 39929999 39510063 39260150 39150204 39320263
            40000317 41340383

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 9, 1:38 PM MDT	Mesoscale Discussion	SPC	Adams, Logan, Morgan, Phillips, Sedgwick, Washington and 2 more	97 min
Jul 9, 2:16 PM MDT	Severe Thunderstorm Watch	SPC	Logan, Morgan, Phillips, Sedgwick, Washington, Weld and 1 more	9 hr
Jul 8, 8:33 PM MDT	Severe Thunderstorm Watch	SPC	Dakota, Dixon	5 hr
Jul 9, 1:41 AM MDT	Mesoscale Discussion	SPC	Cedar, Dakota, Dixon	34 min

Nearby

Mesoscale Discussions in Nebraska, 2021 Mesoscale Discussions in Colorado, 2021 Mesoscale Discussions in Kansas, 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.