558
ACUS01 KWNS 170543
SWODY1
SPC AC 170541

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1241 AM CDT Mon Jun 17 2024

Valid 171200Z - 181200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
THE CENTRAL AND NORTHERN PLAINS INTO THE UPPER MISSISSIPPI VALLEY...

...SUMMARY...
Scattered strong to severe storms are possible across the central
and northern Plains into the upper Mississippi Valley.

...Central/Northern Plains-upper MS Valley...

Strong upper trough is currently located over the Pacific Northwest.
This feature is forecast to shift into the northern inter mountain
region by mid day, then into the northern Rockies by 18/00z, as an
80kt 500mb speed max rotates through the trough to near the ID/WY
border. This is a very dynamic trough and latest model guidance
suggests a surface low will be well identifiable over central WY by
mid day. As the upper trough approaches the northern Plains late in
the period, surface low should reposition itself downstream and
track from the NE Panhandle into southeast ND by sunrise Tuesday.
This evolution will encourage a warm front to advance north across
the upper MS Valley during the latter half of the period, though
warm-advection precipitation may slow its northward advance a bit.

Early this morning, a notable uptick in warm-advection convection is
observed across the central Plains from western NE into southeast
SD. This activity should spread/develop northeast along/north of the
warm front across southern MN into the upper Great Lakes region.
Elevated convection may pose a risk for hail. While the primary
concern for thunderstorms will be along the cool side of the
boundary, strong heating south of the front will allow surface
parcels to approach their convective temperatures. Forecast
soundings suggest negligible CINH will be noted across southeast MN
into central WI along the boundary. If thunderstorms can evolve,
deep-layer shear may support supercell development. Have adjusted
SLGT risk along the warm front to account for both elevated and
potentially warm sector storms.

Upstream across the High Plains, strong boundary-layer heating is
expected across the central High Plains of eastern CO into southwest
NE. As temperatures warm into the lower 90s convective temperatures
will be breached and isolated supercells should develop. Forecast
soundings exhibit substantial SBCAPE (>3000 J/kg) and steep lapse
rates, along with favorable shear for sustained rotating updrafts.
Very large hail may accompany this activity. Some tornado threat
will also be noted with these storms.

Strong dynamic forcing will encourage convection to develop across
the High Plains of northeast WY/southeast MT immediately ahead of
the surging cold front. This activity will spread northeast ahead of
the short wave into the Dakotas during the overnight hours. After
sunset, marked increase in the LLJ is expected across the Plains
from eastern NE into western MN. Severe threat will shift into the
upper Red River Valley by the end of the period.

..Darrow/Thornton.. 06/17/2024

$$