Subj : MESO: Mesoscale Discussion 1489
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Mon Jul 10 2023 22:35:06

ACUS11 KWNS 102235
SWOMCD
SPC MCD 102234=20
MTZ000-110100-

Mesoscale Discussion 1489
NWS Storm Prediction Center Norman OK
0534 PM CDT Mon Jul 10 2023

Areas affected...parts of southwest through central Montana

Concerning...Severe potential...Watch unlikely=20

Valid 102234Z - 110100Z

Probability of Watch Issuance...20 percent

SUMMARY...A cluster of thunderstorms may continue to develop and
organize while spreading into central Montana near and south of
Lewistown through 7-9 PM MDT.

DISCUSSION...Convection has been consolidating across the mountains
of southwestern Montana into the Helena vicinity during the past
hour or two, likely aided by forcing for ascent downstream of a
short wave trough now progressing northeastward into the Canadian
and northern U.S. Rockies.  Embedded with modest (but
strengthening), deep layer west-southwesterly mean flow, largely due
to 30-50 kt speeds in the 500-300 mb layer, the downstream
environment has become characterized by deep boundary-layer mixing.=20
Although not particularly moist, it may still be characterized by
CAPE in excess of 500 J/kg.  And strong vertical shear, due to
pronounced veering with height, might support the evolution of an
increasingly organized system into central Montana near and south of
the Lewistown by 01-03Z.  This may be accompanied by a risk for
small to marginally severe hail, and perhaps a developing swath of
strong gusts approaching or occasionally briefly exceeding severe
limits.

...Kerr/Guyer.. 07/10/2023

....Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj=
g!5rSJiYYXikS52oWSRGgEhi03jAse5LX3o2-iF5gi2yK_mUMRYU2Fv-PkGgqq0BABG6alApSh0=
h8q9CkhXSBAIuAd9eo$  for graphic product...

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

LAT...LON   47051147 47470904 46840795 45970928 46081109 46051188
            47051147=20


=3D =3D =3D
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