Subj : MESO: Mesoscale Discussion 1957
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Sat Aug 16 2025 00:22:35

ACUS11 KWNS 160021
SWOMCD
SPC MCD 160021=20
SDZ000-NEZ000-160215-

Mesoscale Discussion 1957
NWS Storm Prediction Center Norman OK
0721 PM CDT Fri Aug 15 2025

Areas affected...southern South Dakota and northern Nebraska

Concerning...Severe potential...Watch possible=20

Valid 160021Z - 160215Z

Probability of Watch Issuance...60 percent

SUMMARY...As thunderstorms move into the higher instability airmass,
the potential for large to significant hail and damaging winds may
increase. The area will be monitored through the evening for a
potential severe thunderstorm watch.

DISCUSSION...Thunderstorms continue to develop/increase in number
across northern Nebraska and western South Dakota along the northern
periphery of a southern Plains mid-level ridge. The strongest of
these thunderstorms have a history of producing severe caliber winds
and large hail. In particular, a severe storm moving through Sioux
County Nebraska produce a measured 68 mph wind gust at the Montrose
mesonet site.=20

The number of storms in the area should continue to increase this
evening as the region begins to experience increasing large-scale
ascent associated with a mid-level trough rotating along the
periphery of the southern Plains ridge. As the storms move east into
the most unstable airmass, the degree of instability (MUCAPE > 5000
J/kg), will support large to significant sized hail and damaging
wind gusts with any isolated updraft/thunderstorm. Additionally,
with time, as the number of storms increases, a consolidation of
cold pools may support an increased damaging wind threat.=20

Trends will be monitored through the evening for an increase in
intense thunderstorm coverage, or imminent signs of congealing cold
pools. In the event that either are identified, a severe
thunderstorm watch may be needed across portions of the area.

...Marsh/Guyer.. 08/16/2025

....Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj=
g!5P2noa63RRoUQDODzYmoTE_C642HFFlAR_URFsy89prTMafB9CiE61NM82zKbK-BtMclU0Z1Z=
hC-VX8qzaD6Fa5SxOs$  for graphic product...

ATTN...WFO...FSD...ABR...LBF...UNR...CYS...

LAT...LON   42520354 42950383 43860327 44340210 44619978 44439857
            43909817 43109849 42560019 42400216 42520354=20

MOST PROBABLE PEAK WIND GUST...65-80 MPH
MOST PROBABLE PEAK HAIL SIZE...1.50-2.50 IN


=3D =3D =3D
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