Alert archive / Nebraska / Mesoscale Discussions in 2021

Mesoscale Discussion 1579

August 22, 20217 counties in Nebraska

The Storm Prediction Center issued this mesoscale discussion at Aug 22, 2021, 7:06 PM CDT for 7 counties in Nebraska. It was in force for 114 min.

The area

The outline as issued.

The facts

Issued
Aug 22, 2021, 7:06 PM CDT (00:06 UTC)
Expired
Aug 22, 2021, 9:00 PM CDT
In force
114 min
Issued by
the Storm Prediction Center
Concerning
Severe thunderstorm watch 456

Counties Adams County, NE, Clay County, NE, Franklin County, NE, Harlan County, NE, Kearney County, NE, Nuckolls County, NE, Webster County, NE

The radar

The Grand Island radar (KUEX), 41 km from the middle of the area, began a volume at 00:07 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, 0.1 hours before the alert went out and 174 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 2021-08-23Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1090 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 2021-08-23The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -20 square meters per square second.1939587897Sfc1 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
1090 J/kg
Mixed-layer CIN
-125 J/kg
Mixed-layer LCL
2089 m above ground
0-6 km bulk shear
40 kt
0-1 km storm-relative helicity
-20 m²/s²
0-3 km storm-relative helicity
44 m²/s²
Significant tornado parameter
0.0
Supercell composite
1.9

Open this sounding in Storm Lab

The text

As transmitted.

793 
ACUS11 KWNS 230006
SWOMCD
SPC MCD 230006 
NEZ000-KSZ000-230200-

Mesoscale Discussion 1579
NWS Storm Prediction Center Norman OK
0706 PM CDT Sun Aug 22 2021

Areas affected...South-Central Nebraska and North-Central Kansas

Concerning...Severe Thunderstorm Watch 456...

Valid 230006Z - 230200Z

The severe weather threat for Severe Thunderstorm Watch 456
continues.

SUMMARY...The threat for large hail and damaging winds continues
with storms moving eastward along/near the Nebraska-Kansas border
for the next few hours.

DISCUSSION...A dominant storm in south-central Nebraska that has
produced severe weather across Red Willow and Furnas Counties
continues to surge eastward and has merged with convection in Harlan
County. The environment, characterized by MLCAPE around 3000 J/kg
and effective bulk shear of 40 knots, should support a continuation
of the severe threat (especially wind) with the eastward-evolving
cluster of storms.  After sunset, the convective inhibition is
expected to increase rapidly as the surface cools and southwesterly
low-level jet advects drier air into the region.  As a result, the
severe threat is expected to diminish by 03Z.

..Jirak/Grams.. 08/23/2021

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

ATTN...WFO...GID...GLD...

LAT...LON   40129995 40439961 40559916 40569887 40579837 40529793
            40399786 39999796 39869836 39859910 39859982 40129995

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.