740
ACUS01 KWNS 111955
SWODY1
SPC AC 111954

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0254 PM CDT Sat Oct 11 2025

Valid 112000Z - 121200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS 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 could occur over the
Outer Banks of North Carolina late tonight and early Sunday morning.

...20z Update...
No changes are needed to the current D1 Convective Outlook. Daytime
heating is underway after morning cloud cover with cu development
evident across the high terrain in northern Arizona and much of
Utah. Convection is likely to increase in coverage and intensity
this afternoon with approaching large scale ascent. The marginally
unstable air mass and strong deep layer shear should support a few
stronger storms capable of a few instances of hail and gusty winds.

The Marginal risk continues across coastal North Carolina/Outer
Banks in anticipation of the surface low/warm front approaching
later this evening. Guidance continues to indicate a few rotating
storms may approach the coast by late evening/early morning with
potential for a tornado or gusty winds.

..Thornton.. 10/11/2025

.PREV DISCUSSION... /ISSUED 1130 AM CDT Sat Oct 11 2025/

...Great Basin/Southwest...
A prominent trough centered over the Pacific Northwest and northern
California early today will shift eastward over the Great Basin and
northern Intermountain region through tonight. This will be
accompanied by considerable height falls/forcing for ascent and
strengthening deep-layer southwesterly flow and an
eastward-advancing cold front. Ahead of this system, a broad fetch
of tropical moisture emanating from the eastern Pacific will
continue to stream northward, with seasonally rich low/mid-level
moisture expected across parts of the Southwest and southern Great
Basin.

As early day cloudiness quickly shifts eastward and abates, stronger
daytime heating is expected, namely across parts of western/central
Utah and central/southern Arizona. 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 (maximized across Utah) 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.

...Coastal North Carolina/Outer Banks...
A surface low and warm front will approach late tonight/early
Sunday, allowing for upper 60s to low 70s surface dewpoints to
approach and potentially advect inland as east-northeasterly
low-level flow strengthens late tonight. While lapse rates aloft
will remain poor, some buoyancy increase is expected. While inland
warm sector development remains uncertain, 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 across the
Outer Banks/coastal North Carolina.

...East-central Montana...
A couple of stronger storms with gusty winds could materialize this
afternoon/early evening across the region, but it still seems that
the potential for severe storms will be limited by meager
moisture/buoyancy.

$$