737
ACUS01 KWNS 111241
SWODY1
SPC AC 111240

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0740 AM CDT Sat Oct 11 2025

Valid 111300Z - 121200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE GREAT BASIN/SOUTHWEST...AND COASTAL NORTH CAROLINA...

...SUMMARY...
Isolated severe thunderstorms are possible this afternoon and
evening across the eastern Great Basin and Southwest. A brief
tornado and occasional strong to severe gusts may occur over the
Outer Banks of North Carolina during the early morning Sunday.

...Great Basin/Southwest...
A large-scale upper trough over the western states this morning will
advance inland today across the northern Rockies and Great Basin. At
the surface, a cold front will also develop eastward across these
areas through the period, while becoming less well defined into the
Southwest. A broad fetch of tropical moisture emanating from the
eastern Pacific will continue to stream northward ahead of the upper
trough, with rich low/mid-level moisture expected across parts of
the Southwest and southern Great Basin. Ongoing cloudiness and
precipitation across eastern UT/western CO into AZ will hinder
daytime heating to some extent. Greater instability should develop
on the periphery of the morning precipitation, namely across parts
of western/central UT and central/southern AZ. Still, mid-level
lapse rates are expected to remain modest across these areas, and
only weak instability is forecast where filtered diurnal heating can
occur.

Current expectations are for a gradual increase in coverage and
intensity of thunderstorms this afternoon and evening across parts
of the eastern Great Basin into the Southwest as large-scale ascent
associated with the upper trough overspreads these areas. Occasional
hail may occur with the stronger cores, as around 30-40 kt of
deep-layer shear (locally greater across UT) supports organized
updrafts. Otherwise, isolated strong to severe gusts should be the
main threat with scattered to numerous thunderstorms that will
spread east-northeastward through the afternoon and evening. The
only appreciable change to the Marginal Risk with this update was to
expand it southward into more of central/southern AZ where somewhat
greater heating/instability is forecast to occur/develop later
today.

...Coastal North Carolina/Outer Banks...
A slow-moving upper trough/low over the Southeast will encourage a
surface low to deepen off the coast of the Carolinas during the
latter half of the period. This feature may approach the NC Coast
early Sunday morning, which will prove favorable for upper 60s to
low 70s surface dewpoints to advect inland as east-northeasterly
low-level flow strengthens late tonight. While lapse rates aloft
will remain poor, some buoyancy increase is expected. Ample forecast
low-level and deep-layer shear suggest some risk for a tornado and
gusty winds with any supercell that can form in this environment and
move inland across the Outer Banks/coastal NC.

...Northern High Plains...
Strong ascent preceding the ejecting upper trough will overspread
the northern Rockies and adjacent High Plains this afternoon and
evening. This should support isolated to scattered thunderstorms
initially developing over the higher terrain to move northeastward
across parts of southern/eastern MT. Low-level moisture should
remain fairly limited across this area, and lapse rates aloft are
forecast to be modest. This should hinder the degree of instability
which can develop. Still, enhanced mid-level flow may still support
some threat for strong/gusty winds with any convection that
persists. The overall severe threat appears too isolated to include
low wind probabilities at this time, although trends will be
monitored.

..Gleason/Squitieri.. 10/11/2025

$$