ACUS11 KWNS 291934
SWOMCD
SPC MCD 291933=20
WYZ000-MTZ000-292130-

Mesoscale Discussion 1833
NWS Storm Prediction Center Norman OK
0233 PM CDT Tue Jul 29 2025

Areas affected...Northwest Wyoming into southern Montana

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

Valid 291933Z - 292130Z

Probability of Watch Issuance...60 percent

SUMMARY...A severe thunderstorm watch may be needed this afternoon
across portions of northern Wyoming into southern Montana in
anticipation of severe thunderstorms capable of large hail and
damaging wind gusts.

DISCUSSION...Convective initiation is well underway across portions
of Yellowstone National Park into southern/central Montana, with
storms anticipated to move off the higher terrain and into the
better buoyancy this afternoon. MLCAPE at or exceeding 1000 J/kg,
combined with 30-40 kts of deep layer shear is expected to support
organized thunderstorms capable of large hail and damaging winds.=20

Current SPC surface objective mesoanalysis shows Significant Hail
Parameter values of 1.5-2.0 across portions of southeastern Montana.
RAP/HRRR forecast profiles over the next few hours in the vicinity
of northern Wyoming into Montana corroborate this with steep
low-level lapse rates and strong deep-layer shear. Depending on the
location, low-level wind profiles vary from straight-line (favoring
supercell splits), to cyclonically curved (favoring right supercell
motions). Either scenario will support a large hail threat,
including significant (2.00+ inch) hail with the most robust,
isolated thunderstorms. The steep low-level lapse rates, coupled
with higher LCL heights/dryer boundary layer profiles in the
deeply-mixed air will also support a severe wind threat that will be
maximized with any bowing outflow segments.=20

A severe thunderstorm watch may be needed within the next few hours.

..Halbert/Smith.. 07/29/2025

...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!4b_K9mXwQjJ5BXIgh5OPj23oso12I1Y1mURbO4iEDGA7kX8yh74hq3TYQXHZlsIQw4QhYJCM_= RHCHUQ-n_dWXZad_Pg$ for graphic product...

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

LAT...LON 43750940 44260979 44631016 44901050 45171078 45311105
45481123 45831152 46051166 46381159 46811105 47061041
47120980 47120919 47050874 46830819 46730797 46340753
45600725 45060734 44510751 44330773 44060810 43800862
43660908 43680925 43750940=20

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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