050
ACUS02 KWNS 020449
SWODY2
SPC AC 020447

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1147 PM CDT Wed Oct 01 2025

Valid 031200Z - 041200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FRIDAY AFTERNOON
INTO FRIDAY EVENING ACROSS PARTS OF THE EASTERN GREAT BASIN AND
ADJACENT NORTHERN ROCKIES...

...SUMMARY...
Scattered strong thunderstorms may impact parts of the northern
intermountain region into northern Rockies, accompanied by at least
some risk for severe wind and hail late Friday afternoon and
evening.

...Discussion...
Models continue to indicate that generally weaker, but more
amplified, flow will prevail across the southern mid-latitudes of
the eastern Pacific into western Atlantic through this period, with
a stronger somewhat more progressive regime across the northern
mid-latitudes.  Within this regime, large-scale mid-level ridging
offshore of the North American Pacific coast may continue to build
through much of the eastern Pacific, where both streams may become
largely in phase.  Downstream, while mid-level troughing, with a
couple of embedded smaller-scale perturbations, may progress across
the Canadian Rockies into the Canadian Prairies, another notable
short wave trough is forecast to continue to digging across the
Sierra Nevada into the Great Basin Friday through Friday night.

Farther east, broad southern mid-latitude mid-level ridging may
slowly shift eastward across the Ohio Valley through Mid Atlantic
vicinity, while in lower latitudes weak mid/upper troughing lingers
across the Gulf Basin into southwestern Atlantic.

Beneath this regime, it appears that surface ridging will be
maintained, but continue to slowly weaken, from the Gulf Coast and
southern Great Plains into the mid-latitude western Atlantic.  While
surface troughing may modestly deepen across the northern Great
Plains into the lee of the Front Range, a substantive return flow of
low-level moisture emanating from the Gulf Basin will continue to be
impeded.  Even so, some continuing gradual increase in surface dew
points appears possible along and southeast of the surface
troughing, which may contribute to modest diurnal boundary-layer
destabilization beneath a north-northeastward advecting plume of
warm and capping elevated-mixed layer air.

...Eastern Great Basin and adjacent northern Rockies...
Mid-level cooling and forcing for ascent, downstream of the fairly
vigorous short wave trough, are likely to contribute to at least
weak boundary-layer destabilization in a corridor ahead of an
associated surface cold front by late Friday afternoon.  It appears
that this will coincide with strengthening of southwesterly
mid-level flow (including to 50-60+ kt around 500 mb), which will
contribute to strong shear supportive of organized convective
development.  This may include a few supercell structures posing a
risk for severe wind and hail, particularly near the exit region of
the mid-level jet spreading across parts of southeastern Idaho into
southwestern Montana and western Wyoming.  Farther south, across
parts of eastern Utah into western Colorado, thermodynamic profiles,
including a warmer and more deeply mixed boundary-layer, may be more
conducive to primarily a severe wind threat into early Friday
evening.

..Kerr.. 10/02/2025

$$