SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1254 AM CDT Thu Aug 25 2022
Valid 251200Z - 261200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PARTS OF
WESTERN MONTANA AND PORTIONS OF THE CENTRAL INTO NORTHERN HIGH
PLAINS...
...SUMMARY...
A couple of severe thunderstorms are possible across portions of
western Montana and into the central and northern High Plains today.
Severe gusts and large hail are the main threats.
...Synopsis...
Broad cyclonic upper flow will prevail across the eastern U.S. as a
pair of mid-level impulses traverse the northern Rockies and
northern High Plains today. Mainly general thunderstorms are
expected to develop under the cyclonic upper flow regime across the
Mid MS and OH Valleys as well as the Southeast/Florida this
afternoon. A strong to potentially severe wind gust could develop
with storms ahead of the cold front along the MO/IL border, or with
pulse-cellular convection in FL, but the severe threat should remain
too sparse to warrant severe probabilities. On the other hand,
modest convective organization could occur with storms associated
with the aforementioned mid-level impulses across parts of western
MT and along the WY/SD border area despite weak shear. Scattered
strong storms appear likely, and low-end organized severe potential
could be realized.
...Western Montana Vicinity...
Scattered high-based thunderstorms should develop by early to
mid-afternoon across far western MT given adequate diurnal heating
and the passage of the aforementioned mid-level impulse. A modestly
moist low-level airmass overspread by 7-8 C/km mid-level lapse rates
will support 1500-2000 J/kg MLCAPE ahead of the storms. Modest
mid-level westerly flow associated with the passing impulse will
overspread southeasterly low-level flow, contributing to somewhat
curved, elongated hodographs. The anticipated overlapping
kinematic/thermodynamic profiles should support multicellular storm
clusters and perhaps a couple of transient supercells, accompanied
by mainly an isolated severe hail/wind threat.
...Central into northern High Plains...
Scattered thunderstorms will develop along the immediate lee of the
Rockies over eastern WY by afternoon. 7-8 C/km mid-level lapse rates
overspreading surface temperatures in the upper 70s to near 80 F
will contribute to 1000-2000 J/kg MLCAPE. Upslope easterly low-level
flow will veer to more westerly in the mid-levels, contributing to
modestly curved hodographs, supporting multicell/transient supercell
structures initially. Very isolated bouts of large hail will be the
primary threat with these storms, with severe gusts gradually
becoming a greater concern as storms and their cold pools merge.
..Squitieri/Kerr.. 08/25/2022
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