Alert archive / Nebraska / Mesoscale Discussions in 2021

Mesoscale Discussion 1422

August 5, 20219 counties in Nebraska

The Storm Prediction Center issued this mesoscale discussion at Aug 5, 2021, 6:05 PM CDT for 9 counties in Nebraska. It was in force for 55 min.

The area

The outline as issued.

The facts

Issued: Aug 5, 2021, 6:05 PM CDT (23:05 UTC)
Expired: Aug 5, 2021, 7:00 PM CDT
In force: 55 min
Issued by: the Storm Prediction Center
Concerning: Severe potential...watch unlikely
Chance of a watch: 5%

Counties Blaine County, NE, Brown County, NE, Garfield County, NE, Holt County, NE, Keya Paha County, NE, Loup County, NE, Rock County, NE, Valley County, NE, Wheeler County, NE

The radar

The North Platte radar (KLNX), 86 km from the middle of the area, began a volume at 23:03 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 12:00Z, 11.1 hours before the alert went out and 150 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: 630 J/kg
Mixed-layer CIN: -219 J/kg
Mixed-layer LCL: 1661 m above ground
0-6 km bulk shear: 26 kt
0-1 km storm-relative helicity: 73 m²/s²
0-3 km storm-relative helicity: 87 m²/s²
Significant tornado parameter: 0.0
Supercell composite: -0.0

Open this sounding in Storm Lab

The text

As transmitted.

680 
ACUS11 KWNS 052306
SWOMCD
SPC MCD 052305 
NEZ000-SDZ000-060000-

Mesoscale Discussion 1422
NWS Storm Prediction Center Norman OK
0605 PM CDT Thu Aug 05 2021

Areas affected...North-central Nebraska

Concerning...Severe potential...Watch unlikely 

Valid 052305Z - 060000Z

Probability of Watch Issuance...5 percent

SUMMARY...A low-end risk for damaging wind gusts or hail is possible
early this evening.

DISCUSSION...A cluster of storms across north-central Nebraska has
shown occasional organization supportive of damaging wind gusts and
or severe hail. Located at the nose of a plume of mid-level lapse
rates near 8-9 C/km, these storms are ongoing in 1000-2000 J/kg of
MLCAPE from SPC mesoanalysis. Deep-layer shear of 40-50 kts will
favor organized multicell and weak supercell structures. If
convection is able to sustain itself, a brief risk for damaging wind
gusts and severe hail may evolve. To the south and east, the near
storm environment rapidly becomes hostile for deep convection, with
warm mid-level temperatures and large scale subsidence. Storms will
likely weaken as they track south and east over the next 1 to 2
hours but, a brief window of severe risk may develop. Given the
limited spatial and temporal risk, a weather watch is unlikely.

..Lyons/Hart.. 08/05/2021

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

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

LAT...LON   43020054 42989926 42549865 42029837 41649858 41429901
            41389956 41620009 42380054 42820068 43020054

Nearby

Mesoscale Discussions in Nebraska, 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.