914
ACUS01 KWNS 180540
SWODY1
SPC AC 180539

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1139 PM CST Mon Nov 17 2025

Valid 181200Z - 191200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE LOWER
OHIO VALLEY REGION...

...SUMMARY...
A few strong to severe storms are possible across portions of the
Lower Ohio Valley region.

...Lower OH Valley...

Central Plains upper trough is shifting east toward the mid MS
Valley, in line with latest model guidance. As a 60+kt 500mb speed
max translates across MO into southern IL/IN, this feature will
advance into the lower OH Valley by 19/00z, suppressing the height
field as far south as the OH River. Veered, but strong LLJ will
focus across southern MO-southern IL/IN before being nudged
downstream into eastern KY/southern OH by early evening. Net result
will be for a NW-SE oriented corridor of warm advection to shift
east during the day ahead of a weak surface low near the base of the
short-wave trough.

Earlier thoughts regarding the potential for severe continue as
instability will gradually increase along this corridor as midlevel
temperatures cool and lapse rates steepen a bit. In the absence of
strong boundary-layer heating, the majority of convection that
develops across this region will be elevated and aided in large part
by the LLJ. Forecast soundings suggest lifted parcel level will
gradually lower by late afternoon such that near-surface based
parcels could yield modest instability (800-1000 J/kg). Primary
concern today will be hail with elevated supercells, but some
tornado risk is possible with late-day storms, where parcel lift
reflects lower 60s dew points that are expected to return toward the
confluence of the MS/OH Rivers during the afternoon.

...Lower Colorado River Valley/southwest AZ...

Weak midlevel height falls will spread across the lower CO River
Valley today as the upper low off the southern CA Coast eventually
settles toward the international border/northern Baja Peninsula. As
this features digs southeast, a weak LLJ should extend across
southwestern AZ into the early part of the afternoon. Latest
thinking is scattered convection should evolve ahead of the cold
front as it surges across the lower CO River Valley. Forecast
soundings exhibit ample shear for organized rotating updrafts, but
buoyancy is expected to be weak. Given the modest lapse rates, there
is concern updrafts may struggle a bit and hail is expected to
remain below severe levels. Some consideration was given to adding a
2 percent probability for the risk of a brief tornado but will hold
off at this time given the marginality of the situation.

..Darrow/Moore.. 11/18/2025

$$