Subj : MESO: Mesoscale Discussion 1704
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Fri Jul 18 2025 01:06:39

ACUS11 KWNS 180104
SWOMCD
SPC MCD 180104=20
MTZ000-180230-

Mesoscale Discussion 1704
NWS Storm Prediction Center Norman OK
0804 PM CDT Thu Jul 17 2025

Areas affected...North-central into eastern MT

Concerning...Severe Thunderstorm Watch 522...

Valid 180104Z - 180230Z

The severe weather threat for Severe Thunderstorm Watch 522
continues.

SUMMARY...A threat for hail and localized severe gusts will continue
through the evening.

DISCUSSION...One supercell is ongoing at 01 UTC across parts of
Phillips County in MT, with another supercell east of Great Falls. A
compact but vigorous mid/upper-level shortwave trough is moving
across southeast AB and northern MT, and ascent attendant to this
shortwave will help these isolated to widely scattered cells persist
through the evening.

With relatively modest low-level moisture and generally weak
midlevel lapse rates (as observed in the 00Z GGW sounding), buoyancy
is rather modest, with MLCAPE generally in the 500-1000 J/kg range.
However, very favorable deep-layer shear (with effective shear of
50-60 kt) and elongated mid/upper-level hodographs will support some
hail threat with any sustained supercells, despite the marginal
instability. Localized strong to severe gusts may also accompany
these cells through the evening, especially if any storm clustering
occurs.=20

Farther south, an earlier discrete cell has weakened across
southeast MT. While instability is somewhat greater compared to
areas farther north, this region is further removed from the primary
shortwave trough, and any severe threat in this area is expected to
remain isolated in the short term. There is some potential for one
or more of the northern MT cells to eventually approach east-central
and southeast MT near and after dusk.

...Dean.. 07/18/2025

....Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj=
g!7o5KpSBaMBdHgK75iQyboyyHCXx2uc7cWoBPQwqGPxc5-prVcs5D05H3ohieWhbGLOk2C8Kp-=
hBnCSrncL_xs4gwNZw$  for graphic product...

ATTN...WFO...BYZ...GGW...TFX...

LAT...LON   47190961 47730965 48970855 48960620 47830552 47060521
            46390559 45910594 45890724 46610885 47190961=20

MOST PROBABLE PEAK WIND GUST...55-70 MPH
MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN


=3D =3D =3D
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