Mesoscale Discussion 1093

Issued

Jun 25, 2021, 12:21 PM MDT (18:21 UTC)

Expired

Jun 25, 2021, 2:15 PM MDT

In force

114 min

Issued by

the Storm Prediction Center

Concerning

Severe potential...watch possible

Chance of a watch

40%

The Grand Island radar (KUEX), 103 km from the middle of the area, began a volume at 18:22 UTC, the scan nearest the moment this went out.

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• Severe Thunderstorm Watch 316Jun 25, 2:05 PM MDT

292 
ACUS11 KWNS 251822
SWOMCD
SPC MCD 251821 
NEZ000-KSZ000-COZ000-252015-

Mesoscale Discussion 1093
NWS Storm Prediction Center Norman OK
0121 PM CDT Fri Jun 25 2021

Areas affected...Southern Nebraska

Concerning...Severe potential...Watch possible 

Valid 251821Z - 252015Z

Probability of Watch Issuance...40 percent

SUMMARY...Thunderstorm coverage and intensity should gradually
increase through the afternoon and into the early evening hours. A
watch may be needed to address the severe hail and wind potential.

DISCUSSION...Weak convective showers continue to linger in the
vicinity of an MCV across southwest NE. While occasional lightning
strikes have been noted with this activity, overall trends have
shown little intensification over the past hour. Temperatures across
southern NE continue to warm into the upper 70s and low 80s, which
is slowly eroding remaining MLCIN and increasing instability to near
1000-1500 J/kg MLCAPE (per recent mesoanalysis and hinted at by
diminishing low-level stratus). Upstream convection across far
northern CO has been intensifying over the past 30-60 minutes,
suggesting that stronger forcing for ascent may be approaching the
region. Additionally, a few deepening convective towers are noted in
GOES 1-min imagery along the effective warm front ahead of the MCV.
These trends support the idea that a gradual increase in convective
intensity is likely in the coming hours. While the number of
convective showers/towers suggest coverage will increase as well,
recent hi-res guidance hints that coverage may be limited to only
isolated cells. 

Elongated hodographs featuring 35-40 knots of effective bulk shear
and a nearly unidirectional wind profile - especially north of an
effective warm front where easterly winds are noted - will support
organized convection with splitting supercells initially possible.
Given sufficient coverage, storm interactions may favor upscale
growth and an increasing wind threat as storms move east/northeast
along the effective warm front/instability gradient. One or two
bowing segments are possible, but confidence is somewhat low given
uncertainties in storm coverage. Conditions will continue to be
monitored, and a watch may be needed in the coming hours to address
the hail and damaging wind potential.

..Moore/Guyer.. 06/25/2021

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

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

LAT...LON   39340231 40110257 40920222 41340134 41620012 41619871
            41669739 41489686 40729667 40029680 39939753 39589888
            39310011 39170102 39340231

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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.