Mesoscale Discussion 316

Issued

Apr 6, 2021, 3:03 PM CDT (20:03 UTC)

Expired

Apr 6, 2021, 5:00 PM CDT

In force

117 min

Issued by

the Storm Prediction Center

Concerning

Severe potential...watch possible

Chance of a watch

40%

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• Severe Thunderstorm Watch 72Apr 6, 4:45 PM CDT

879 
ACUS11 KWNS 062004
SWOMCD
SPC MCD 062003 
KSZ000-NEZ000-062200-

Mesoscale Discussion 0316
NWS Storm Prediction Center Norman OK
0303 PM CDT Tue Apr 06 2021

Areas affected...Parts of south central Nebraska into western
portions of central Kansas

Concerning...Severe potential...Watch possible 

Valid 062003Z - 062200Z

Probability of Watch Issuance...40 percent

SUMMARY...Scattered vigorous thunderstorm development is possible
across the region by 5-6 PM CDT, with large hail expected to be the
primary potential severe hazard into early evening.

DISCUSSION...Seasonably strong boundary-layer heating/mixing is
ongoing, within a narrow pre-cold frontal corridor wrapping into the
vicinity of a modest surface cyclone centered west/northwest of Hill
City, KS.  To the east of this axis, weak to modest low-level
moisture return on southerly low-level flow continues.  Beneath
rather steep mid-level lapse rates associated with warm and capping
elevated mixed-layer air, it appears that this is contributing to
mixed-layer CAPE up to around 1500 J/kg, east of Dodge City through
Russell, KS, into the vicinity of Lexington, NE.

Meanwhile, just to the west, it appears that at least weak mid-level
cooling is underway in response to the east-northeast progression of
an initial impulse within larger-scale mid-level troughing
progressing across and east of the Rockies.  As this begins to
overspread the vicinity of the ongoing axis of boundary-layer
destabilization, mid-level inhibition is expected to weaken
sufficiently to contribute to the initiation of scattered vigorous
thunderstorm activity within the next few hours. The past several
runs of the Rapid Refresh and High Resolution Rapid Refresh have
been suggestive that this may occur as early as 22-23Z.

Although stronger southerly low-level flow, including 30-40+ kt
around 850 mb, appears offset to the east of the instability axis,
deeper-layer shear beneath 40 kt flow near the 500 mb level may
contribute to sufficient shear for the evolution of supercell
structures capable of producing large hail.  Locally strong to
severe surface gusts may also be possible, but a more general
increase in risk for severe wind gusts probably will await
interaction of upscale growing convection with a strengthening
low-level jet later this evening.

..Kerr/Hart.. 04/06/2021

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

ATTN...WFO...ICT...GID...LBF...DDC...GLD...

LAT...LON   40870005 41179909 40719828 39149809 37969829 37609891
            37629962 38789964 40069970 40870005

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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.