Subj : MESO: Mesoscale Discussion 1890
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Tue Aug 05 2025 19:41:16

ACUS11 KWNS 051941
SWOMCD
SPC MCD 051940=20
NDZ000-SDZ000-052145-

Mesoscale Discussion 1890
NWS Storm Prediction Center Norman OK
0240 PM CDT Tue Aug 05 2025

Areas affected...south central North Dakota and adjacent north
central South Dakota

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

Valid 051940Z - 052145Z

Probability of Watch Issuance...60 percent

SUMMARY...Intensifying thunderstorm activity, perhaps including the
evolution of a sustained supercell appears probable by 5-7 PM CDT,
if not earlier, before transitioning to an organizing, southeastward
propagating cluster into this evening.  A severe weather watch will
likely be needed, but timing remains uncertain.

DISCUSSION...In the wake of a generally dissipating cluster of
thunderstorms spreading into the Red River Valley,
lower/mid-tropospheric warm advection is being maintained across
much of the Dakotas, on the northern periphery of a plume of warm
and capping elevated mixed-layer air.  This includes temperatures as
warm as +10 to +12 C around 700 mb, as far northeast as southwestern
North Dakota through north central and northeastern South Dakota,
beneath which stronger boundary-layer warming and destabilization is
ongoing.

Around and north through east of the Bismarck ND vicinity, the
boundary-layer has been slower to modify in the wake of the
preceding convection, but forcing for ascent has been sufficient to
overcome inhibition and support renewed thunderstorm development.=20
This has been gradually increasing near the nose of a 30 kt
southerly low-level jet, which may strengthen a bit further into
early evening.  Northward advection of warmer and more moist
boundary-layer air along this axis is likely to contribute to
substantive further boundary-layer destabilization, and, at some
point, a rapid intensification of thunderstorm activity.=20=20

Once this occurs, in the presence of strong deep-layer shear beneath
30-40 kt westerly 500 mb flow, the environment appears conducive to
the evolution of a significant supercell with potential to produce
large hail and perhaps a couple of tornadoes, before growing growing
upscale into an organizing southeastward propagating cluster by this
evening.

...Kerr/Smith.. 08/05/2025

....Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj=
g!_DHNJX68vJ4MqxkRVkXs6WMv66wl0uCq5NmR3kftNlCulzeeddR8nEZzYt0byh1r5AT4ke-w7=
YNMr6lBU52lalchInw$  for graphic product...

ATTN...WFO...FGF...ABR...BIS...UNR...

LAT...LON   46380187 47080062 46989902 46439791 45929837 45549908
            45379992 45600092 45870202 46380187=20

MOST PROBABLE PEAK TORNADO INTENSITY...85-115 MPH
MOST PROBABLE PEAK WIND GUST...55-70 MPH
MOST PROBABLE PEAK HAIL SIZE...1.50-2.50 IN


=3D =3D =3D
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