ACUS01 KWNS 251957
SWODY1
SPC AC 251956

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0256 PM CDT Sun Aug 25 2024

Valid 252000Z - 261200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE
NORTHERN PLAINS/UPPER MIDWEST AND CENTRAL ROCKIES...

...SUMMARY...
Severe wind gusts and hail are most probable today over parts of the
Four Corners to southwestern Wyoming, and this evening over portions
of the eastern Dakotas and western Minnesota.

...Utah and Wyoming...
Portions of the Marginal risk are were expanded westward across
north-central UT and far western WY into extreme southeast ID to
account for recent convective trends. While this region is on the
fringe of the monsoonal moisture plume, cooler mid-level
temperatures are compensatory and supporting convection with similar
IR/cloud-top temperature presentations as convection further to the
southeast. Thunderstorms should remain more isolated, but sporadic
severe hail and/or wind gusts appear possible.

...Southeast MI/northeast OH...
The Marginal risk area across southeast lower MI into OH has been
removed. Large scale forcing for ascent should remain fairly weak as
the mid-level impulse associated with early-morning convection exits
the region. Low-level ascent along a surface confluence axis may
support a storm or two across southeast lower MI, but confidence in
the overall severe threat appears sufficiently low to warrant
removal of risk probabilities.

..Moore.. 08/25/2024

.PREV DISCUSSION... /ISSUED 1138 AM CDT Sun Aug 25 2024/

...Northern Plains/Upper Midwest...
Scattered thunderstorms are expected to develop along/ahead of the
cold front and near a South Dakota surface wave, primarily this
evening after 00Z/7pm CDT, although enough moistening and heating
may occur for isolated late-afternoon development. Some supercells
and bowing lines/clusters are expected, with large hail and severe
wind gusts possible.

Intensifying thunderstorm development should occur as the front
encounters what is left of a diurnally well-heated and
still-unstable boundary-layer airmass. Forecast soundings indicate
the moist layer should deepen through the day beneath strong capping
and steep mid-level lapse rates, MLCAPE in the 3000-4000 J/kg range
possible. This will occur with gradually strengthening
west-southwesterly winds aloft with 30-45 kt effective shear.

Additional severe storms may occur late this afternoon into evening
within an evolving post-frontal environment across northeast Wyoming
into northwest South Dakota/southwest North Dakota, with moderate
buoyancy and very long/straight hodographs potentially supporting
storms capable of hail and possibly severe-caliber wind gusts.

...Central/southern Rockies...
Scattered thunderstorms are ongoing early today across eastern Utah
and western Colorado in advance of an upper-level trough centered
over Nevada. A greater coverage and intensity of storms should occur
into the afternoon as the boundary layer further warms/destabilizes.
Relatively strong mid/high-level southwesterlies will support ample
deep-layer/effective shear, with supercells and bowing clusters
possible in a corridor spanning portions of the Four Corners area to
northern Colorado/southwest Wyoming. Elongated and semi-straight
hodographs will support large-hail potential aside from a broader
regional risk for severe-caliber wind gusts.

...South-central High Plains...
Scattered slow-moving thunderstorms are expected this afternoon
particularly across eastern Colorado and northeast New Mexico.
Hot/well-mixed boundary layers within the pre-convective environment
will support the possibility of strong to locally severe-caliber
wind gusts through late afternoon until around sunset.

$$