SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0258 PM CDT Thu Aug 25 2022
Valid 252000Z - 261200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER WESTERN
MONTANA AND ACROSS PORTIONS OF THE NORTH-CENTRAL HIGH PLAINS...
...SUMMARY...
Isolated severe hail and thunderstorm gusts will be possible across
portions of western Montana and the north-central High Plains today.
...Discussion...
No appreciable change was made to the previous convective outlook.
Minor adjustments were made to the 10-percent thunderstorm
probability area based on visible-satellite imagery and lightning
data.
..Smith.. 08/25/2022
.PREV DISCUSSION... /ISSUED 1120 AM CDT Thu Aug 25 2022/
...Western MT...
Slow-moving closed upper low over near the international border in
the vicinity of northern ID will begin to move slowly east late
today. Diurnal heating of initially 50s surface dew points will
result in a deep mixed layer, and steep midlevel lapse rates will
contribute to 1000-1500 J/kg MLCAPE this afternoon. Although winds
throughout the cloud-bearing layer will be generally modest (30 kts
or less), veering low/midlevel flow will contribute to 30-35 kts of
effective shear. Widely scattered to scattered thunderstorm
development is expected this afternoon across western MT, with
multicell/supercell modes possible. Deep mixed layer will result in
a risk for isolated severe wind gusts, and large hail will be
possible with a few stronger updrafts/supercell structures.
...North-Central High Plains...
Midlevel perturbation currently over western WY will continue east,
with a region of ascent favorably timed to develop over the Big
Horn/Black Hills region during the mid/late afternoon. Despite
ongoing cloud cover, heating of mid/upper 50s surface dew points
beneath reasonably steep midlevel lapse rates should result in
pockets of MLCAPE of 1000-1500 J/kg. Modest midlevel west/northwest
flow will contribute to around 30 kts of effective shear which will
favor a mixed multicell/transient supercell mode. Isolated stronger
storms will be capable of strong/damaging gusts and hail through
early evening.
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