SPC MD 2168

SPC MD 2168


Mesoscale Discussion 2168
NWS Storm Prediction Center Norman OK
0208 PM CDT Thu Sep 21 2023

Areas affected…Portions of southern Nebraska and northern Kansas

Concerning…Severe potential…Watch likely

Valid 211908Z – 212115Z

Probability of Watch Issuance…80 percent

SUMMARY…The threat for all severe hazards will exists with storms
that develop this afternoon. A watch is likely for parts of
southwestern Nebraska into northwestern Kansas.

DISCUSSION…An effective warm front is situated from the Nebraska
Panhandle southeastward into south-central Nebraska, reinforced by
convection in northeast Nebraska earlier today. A dryline also
extends southward from a surface low in southwestern Nebraska into
western Kansas. While upper-level forcing is nebulous/subtle,
cumulus development has been noted near the surface low and more
recently along the dryline along the Kansas/Nebraska border. Storm
initiation appears probable in the next couple of hours with the
most likely location being in parts of southwestern Nebraska. Steep
lapse rates (sampled by the 12Z LBF sounding) and dewpoints in the
low 60s F will support 2000-2500 J/kg MLCAPE. Shear is currently
modest, but is expected to increase later this afternoon as the
large-scale trough continues slowly eastward. All severe hazards
will be possible with storms that develop this afternoon, although
the primary risks will be large to very-large (1-3 in.) hail and
severe wind gusts (60-70 mph). The tornado threat will generally be
maximized along the warm front where surface winds remain more
backed. However, the threat will initially be modulated by modest
low-level winds. Storms that can remain discrete later into the
afternoon will potentially pose a greater tornado threat as the
low-level shear increases, particularly in western Kansas. Storms in
western Kansas would likely be more discrete, but their development
is more conditional due to overall weaker forcing. A watch is likely
to be issued this afternoon.

..Wendt/Hart.. 09/21/2023

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


LAT…LON 39060133 39920136 40720164 41300225 41670229 41700074
40959915 40239815 39779829 39349914 38789983 38360084
38540132 39060133

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