338
ACUS03 KWNS 171929
SWODY3
SPC AC 171929

Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0229 PM CDT Fri Jul 17 2026

Valid 191200Z - 201200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CAROLINAS INTO SOUTHEAST VIRGINIA...

...SUMMARY...
Isolated to widely scattered strong to severe thunderstorms may pose
a risk for damaging wind gusts across portions of the southern
Appalachians to the coastal Carolinas/southeast Virginia vicinity on
Sunday. Strong to severe storms may also develop across parts of
eastern Montana into North Dakota and Minnesota.

...Southern Appalachians into the Coastal Carolinas/southern VA...
A broad mid/upper-level trough will remain in place across much of
the eastern CONUS on Sunday. A weakening cold front may become
nearly stationary by afternoon somewhere across southern VA.
Scattered storm development is expected during the afternoon
along/ahead of the remnant frontal zone, and also near the higher
terrain of the southern Appalachians.

Deep-layer flow/shear will generally be weak to modest, but large
PW, steepening low-level lapse rates, and moderate to locally strong
buoyancy will support vigorous updrafts and localized downbursts. In
addition, low/midlevel flow may be sufficient for one or two
outflow-driven clusters to evolve with time and move southeastward
into the early evening, with wind-damage potential.

...Parts of eastern MT into ND/MN...
A vigorous shortwave trough may evolve into a mid/upper-level low as
it moves eastward across the Canadian Prairies on Sunday. An
attendant surface low is forecast to gradually intensify as it moves
toward Lake Winnipeg. A surface trough/weak cold front will move
into northeast MT during the day and across parts of the Dakotas
during the evening.

A conditionally favorable environment is expected to evolve across
parts of far eastern MT into ND and northwest MN during the
afternoon/evening, as a 40-50 kt midlevel jet and steep lapse rates
overspread a warm and relatively moist boundary layer. However, with
the strongest height falls and ascent expected to remain north of
the international border, capping may inhibit diurnal storm
development. Any storms that are able to develop and mature during
the afternoon and early evening could evolve into organized cells or
clusters with severe wind and hail potential.

Even if surface-based diurnal development is suppressed, there will
be some potential for elevated convection to develop Sunday evening
into the overnight. Steep lapse rates, moderate elevated buoyancy,
and sufficient effective shear could support a hail threat with the
strongest elevated storms, and severe-wind potential with any
forward-propagating clusters that can develop Sunday night.

The Level-1/Marginal Risk has been expanded westward across ND and
far eastern MT to account for the conditional threat in these areas,
though confidence in the details of storm coverage and evolution
remains low at this time.

..Dean.. 07/17/2026

$$