148
ACUS01 KWNS 111248
SWODY1
SPC AC 111246

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0746 AM CDT Mon Aug 11 2025

Valid 111300Z - 121200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE SOUTHERN PLAINS...AND OVER PORTIONS OF NORTH DAKOTA INTO
NORTHERN MINNESOTA...

...SUMMARY...
Isolated strong to severe thunderstorms may pose some risk for
severe winds and hail across parts of the southern Plains, and
separately from North Dakota into northern Minnesota, mainly this
afternoon and evening.

...Southern Plains...
Convection has generally weakened this morning across eastern KS,
with a outflow reinforced front advancing southward across the
southern High Plains. This boundary is forecast to stall through the
morning and early afternoon, and it will likely serve as a focus for
renewed thunderstorm development later today. The southern extent of
upper troughing that exists over much of the Plains is forecast to
advance eastward across the southern High Plains this afternoon.
Initial development over the higher terrain of north-central into
northeast NM should occur in a modest low-level upslope flow regime,
with steep lapse rates aloft contributing to moderate instability.
Weak low-level winds will gradually veer to west-northwesterly and
modestly strengthen with height through mid/upper levels, supporting
modest deep-layer shear and some updraft organization.

Isolated severe hail may occur with initially more cellular
development across the southern High Plains, before some clustering
potentially occurs late this afternoon/evening farther east into the
TX Panhandle and northwest TX with more of a wind threat. While
deep-layer shear will likely remain weak farther east across OK, the
front/outflow boundary should aid in at least scattered
thunderstorms developing with moderate to locally strong instability
amid ample daytime heating. Isolated damaging winds via strong
downbursts and marginally severe hail appear possible with the
stronger cores given seasonably cool temperatures aloft (around -10C
at 500 mb with the 12Z OUN observed sounding), and the Marginal Risk
has been expanded eastward for this possibility.

...North Dakota into Northern Minnesota...
Within upper troughing already established over the northern/central
Plains and central Canada, a mid-level shortwave trough and related
surface cold front are forecast to move east-southeastward over ND
and northern MN through the period. Modest low-level moisture
characterized by mid 50s to perhaps low 60s surface dewpoints should
be present ahead of the front across these areas. Diurnal heating
and modestly steepened lapse rates aloft should aid in the
development of weak instability this afternoon. Thunderstorms should
gradually increase in coverage along/ahead of the front this
afternoon/evening as they spread eastward over parts of ND into
northern MN. The stronger cells may produce marginally severe hail,
with sufficient deep-layer shear present for some convective
organization. With time, some clustering/upscale growth along the
front appears probable, with isolated strong to severe gusts
possible. The lack of stronger instability should tend to temper the
overall severe threat.

...Missouri/Iowa...
An MCV generated by overnight/early morning convection across the
southern/central Plains should develop northeastward into parts of
northern MO and IA by this afternoon. It remains unclear whether
sufficient instability to support robust thunderstorms will be able
to develop today ahead of this feature given ongoing convection and
cloud debris. Regardless, some enhancement to the low/mid-level flow
and related deep-layer shear could support updraft organization if
surface-based thunderstorms can develop. Given the continued
uncertainty regarding this potential, have held off on inclusion of
low severe probabilities across this region with this update.

..Gleason/Leitman.. 08/11/2025

$$