Alert archive / Nebraska / Mesoscale Discussions in 2021

Mesoscale Discussion 1634

August 28, 20215 counties in Nebraska

The Storm Prediction Center issued this mesoscale discussion at Aug 28, 2021, 7:28 PM CDT for 5 counties in Nebraska. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued
Aug 28, 2021, 7:28 PM CDT (00:28 UTC)
Expired
Aug 28, 2021, 9:30 PM CDT
In force
2 hr
Issued by
the Storm Prediction Center
Concerning
Severe thunderstorm watch 470

Counties Antelope County, NE, Garfield County, NE, Loup County, NE, Valley County, NE, Wheeler County, NE

The radar

The North Platte radar (KLNX), 144 km from the middle of the area, began a volume at 00:33 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, 0.5 hours before the alert went out and 165 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 2021-08-29Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 2510 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 2021-08-29The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 27 square meters per square second.193958Sfc1 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
2510 J/kg
Mixed-layer CIN
-46 J/kg
Mixed-layer LCL
2148 m above ground
0-6 km bulk shear
27 kt
0-1 km storm-relative helicity
27 m²/s²
0-3 km storm-relative helicity
167 m²/s²
Significant tornado parameter
0.0
Supercell composite
8.7

Open this sounding in Storm Lab

The text

As transmitted.

771 
ACUS11 KWNS 290029
SWOMCD
SPC MCD 290028 
NEZ000-290230-

Mesoscale Discussion 1634
NWS Storm Prediction Center Norman OK
0728 PM CDT Sat Aug 28 2021

Areas affected...central NE

Concerning...Severe Thunderstorm Watch 470...

Valid 290028Z - 290230Z

The severe weather threat for Severe Thunderstorm Watch 470
continues.

SUMMARY...Thunderstorms capable of severe wind/hail will continue
over central NE this evening.

DISCUSSION...Radar/satellite imagery early this evening shows a
southwest-northeast band of embedded cells over central NE.  Surface
analysis indicates this thunderstorm cluster is located on the
front.  Conditions to the east/southeast in the inflow of the storms
remains very warm and humid with upper 80s temperatures and
dewpoints near 70 deg.  The 00z North Platte raob showed 2700 J/kg
MLCAPE and an 8 deg C/km surface to 500 mb lapse rate.  Mid-level
flow is forecast to strengthen over the next few hours as the
shortwave trough over the northern High Plains continues east into
the Dakotas this evening.  The main hazards with the stronger storms
will be large hail and severe gusts.

..Smith.. 08/29/2021

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

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

LAT...LON   41409930 41420007 41700022 42469838 42419784 42059779
            41809790 41409930

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 28, 9:57 PM CDTMesoscale DiscussionSPCBurt, Dodge, Douglas, Washington63 min

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.