Alert archive / Nebraska / Mesoscale Discussions in 2021

Mesoscale Discussion 1231

July 10, 20215 counties in Nebraska

The Storm Prediction Center issued this mesoscale discussion at Jul 10, 2021, 1:37 AM CDT for 5 counties in Nebraska. It was in force for 53 min.

The area

The outline as issued.

The facts

Issued
Jul 10, 2021, 1:37 AM CDT (06:37 UTC)
Expired
Jul 10, 2021, 2:30 AM CDT
In force
53 min
Issued by
the Storm Prediction Center
Concerning
Severe thunderstorm watch 361

Counties Custer County, NE, Dawson County, NE, Lincoln County, NE, Logan County, NE, Thomas County, NE

The radar

The North Platte radar (KLNX), 78 km from the middle of the area, began a volume at 06:37 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 00:00Z, 6.6 hours before the alert went out and 29 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, N. Platte/Lee Bi, NE at 00:00Z on 2021-07-10Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 2799 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, N. Platte/Lee Bi, NE at 00:00Z on 2021-07-10The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 30 square meters per square second.19395878Sfc1 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
2799 J/kg
Mixed-layer CIN
-162 J/kg
Mixed-layer LCL
1859 m above ground
0-6 km bulk shear
47 kt
0-1 km storm-relative helicity
30 m²/s²
0-3 km storm-relative helicity
117 m²/s²
Significant tornado parameter
0.0
Supercell composite
4.9

Open this sounding in Storm Lab

The text

As transmitted.

461 
ACUS11 KWNS 100638
SWOMCD
SPC MCD 100637 
NEZ000-100730-

Mesoscale Discussion 1231
NWS Storm Prediction Center Norman OK
0137 AM CDT Sat Jul 10 2021

Areas affected...portions of western and central Nebraska

Concerning...Severe Thunderstorm Watch 361...

Valid 100637Z - 100730Z

The severe weather threat for Severe Thunderstorm Watch 361
continues.

SUMMARY...Convection has gradually diminished overall, over the past
hour, though local risk for damaging winds may continue for another
hour or two.

DISCUSSION...Latest radar loop shows a well-defined mesolow,
crossing western Nebraska and associated with a bowing arc of storms
along with a well-defined comma head.  Overall however, convection
has gradually decreased in intensity -- in part due to thermodynamic
deficiencies arising from the effects of prior convection now moving
across southeastern Nebraska.

While locally damaging winds remain possible, given the
well-organized nature of the mesoscale circulation and attendant
band of storms, the overall convective trend should remain downward.
 One exception may be on the very southern fringe of the convection
-- over southwestern Nebraska and into portions of northwestern and
north-central Kansas -- where a more favorable thermodynamic
environment is indicated, coincident with warm-advection-induced
ascent associated with a 40 kt southwesterly low-level jet across
western Kansas.  Any storms persisting across this portion of the
area would largely/eventually shift into WW 360.  Otherwise, given
current trends, the current, scheduled 08Z expiration of the watch
appears reasonable, with respect to the gradually diminishing risk.

..Goss.. 07/10/2021

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

ATTN...WFO...GID...LBF...

LAT...LON   41920087 41669932 41369917 40899952 40590048 40790111
            41160122 41920087

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jul 9, 8:21 PM CDTMesoscale DiscussionSPCAdams, Antelope, Arthur, Blaine, Boone, Boyd and 44 more114 min
Jul 9, 8:45 PM CDTSevere Thunderstorm WatchSPCAdams, Antelope, Boone, Buffalo, Cedar, Clay and 28 more8 hr
Jul 9, 9:06 PM CDTSevere Thunderstorm WatchSPCArthur, Blaine, Boyd, Brown, Cherry, Custer and 15 more6 hr
Jul 9, 9:12 PM CDTMesoscale DiscussionSPCBurt, Cass, Cuming, Dodge, Douglas, Gage and 13 more2 hr
Jul 9, 9:58 PM CDTSevere Thunderstorm WatchSPCBurt, Butler, Cass, Cuming, Dodge, Douglas and 14 more7 hr
Jul 9, 10:20 PM CDTMesoscale DiscussionSPCButler, Clay, Fillmore, Gage, Hamilton, Jefferson and 7 more115 min
Jul 9, 10:44 PM CDTMesoscale DiscussionSPCBox Butte, Garden, Grant, Sheridan91 min
Jul 10, 1:45 AM CDTMesoscale DiscussionSPCCuster, Dawson, Lincoln, Logan, Thomas60 min
Jul 10, 1:20 PM CDTMesoscale DiscussionSPCButler, Cass, Douglas, Fillmore, Gage, Jefferson and 12 more115 min
Jul 10, 2:18 PM CDTSevere Thunderstorm WatchSPCCass, Douglas, Gage, Johnson, Lancaster, Nemaha and 4 more7 hr
Jul 10, 3:44 PM CDTMesoscale DiscussionSPCGage, Johnson, Nemaha, Pawnee, Richardson91 min
Jul 10, 5:27 PM CDTMesoscale DiscussionSPCRichardson2 hr

Nearby

Mesoscale Discussions in Nebraska, 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.