Subj : MESO: Mesoscale Discussion 1701
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Thu Jul 17 2025 20:49:20

ACUS11 KWNS 172049
SWOMCD
SPC MCD 172048=20
MTZ000-172245-

Mesoscale Discussion 1701
NWS Storm Prediction Center Norman OK
0348 PM CDT Thu Jul 17 2025

Areas affected...portions of northern and central Montana

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

Valid 172048Z - 172245Z

Probability of Watch Issuance...60 percent

SUMMARY...Isolated to widely scattered thunderstorms are expected
this afternoon and evening. A few supercells capable of hail and
damaging winds are expected. A WW is possible, although it is
uncertain when the severe risk will maximize.

DISCUSSION...Afternoon visible and radar imagery show initial
thunderstorm development is underway across far northern MT and
southern Canada. Aided by synoptic ascent from a shortwave trough
within northwesterly flow and heating along a stalled frontal
boundary, continued convective development is expected over the next
several hours. Modest moisture and somewhat cool surface
temperatures have limited boundary-layer destabilization so far this
afternoon. Still, with little inhibition, weak MLCAPE (500-700 J/kg)
will be sufficient for stronger updrafts. Additional destabilization
is expected as low-level warm advection along the boundary increases
into this evening. Elongated hodographs owing to enhanced
northwesterly flow aloft observed from the 18z TFX RAOB and area
VADs will support a supercell storm mode capable of hail and
isolated damaging gusts.

Despite weaker buoyancy, continued ascent along the stalled front
will likely serve as a focus for storm intensification over the next
couple of hours. This is supported by recent CAM guidance which
shows a few longer-lived supercells into this evening. The exact
timing of the severe risk remains unclear as destabilization
continues and storms may take some time to mature. However, at least
an isolated severe risk should gradually increase over the next few
hours. Given the broadly favorable environment for large hail and
severe gusts, a WW may be needed.

...Lyons/Smith.. 07/17/2025

....Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj=
g!5yAxZqMPRgIvkAniK7jmJsRrBBb8C2BCwGBOex5ucWIoEVDYwMaSAHmGoSCpor30qBD-l0eCy=
Gk_4gqF3Z_PK5qS4Tw$  for graphic product...

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

LAT...LON   49241243 49150908 48360651 47250473 46170558 46080744
            46220885 47141104 47711229 48261283 49241243=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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