243
ACUS48 KWNS 270902
SWOD48
SPC AC 270900

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0400 AM CDT Thu Jun 27 2024

Valid 301200Z - 051200Z

...DISCUSSION...
...D4/Sunday: Eastern MT into western ND...
A mid/upper-level trough will move eastward from the Northwest
toward the northern Rockies on Sunday, with some influence of this
trough reaching the northern High Plains by late afternoon into
early evening. Low-level moisture return north of a surface low
across WY will support moderate destabilization across parts of
eastern MT. Scattered storm development will be possible by early
evening as the mid/upper trough approaches. Increasing midlevel flow
will support initial supercell development, with a threat of large
hail. A strengthening nocturnal low-level jet will aid in potential
MCS development, which may spread some severe-wind potential into at
least western ND Sunday night.

...D4/Sunday: Southern New England into the Mid Atlantic...
Depending on the influence of early-day convection and timing of a
cold front, some modest destabilization may occur from southern New
England into the Mid Atlantic Sunday afternoon. Deep-layer shear
would support some storm organization, and strong to locally severe
storms will be possible.

...D5/Monday: Central/northern Great Plains...
The mid/upper-level trough that moves across the northern Rockies on
Sunday is forecast to emerge over the northern/central Great Plains
on Sunday. Moderate to locally strong destabilization will be
possible near and west of a warm front that is forecast to lift
northeastward through the day. Deep-layer shear will increase as
midlevel height falls overspread the warm sector, and scattered
strong to severe storms may develop in the vicinity of a trailing
surface trough/cold front. Supercells will be possible with initial
development, with a potential tendency for some clustering/upscale
growth with time.

A 15% probability area has been included across parts of SD/NE,
where confidence is currently greatest in severe-storm development.
Some severe threat could also evolve across parts of ND, but there
is greater uncertainty with northward extent due to the potential
for an early-day MCS. Farther east, guidance varies regarding the
potential for destabilization into parts of MN/IA.

...D6/Tuesday: East-central Plains into the upper Midwest...
Some severe threat could spread eastward into parts of the
east-central Plains and Midwest on Tuesday, in conjunction with the
eastward-moving mid/upper-level trough and attendant cold front.
However, predictability is currently too low to include
probabilities, due to uncertainty regarding trough evolution and the
influence of antecedent convection.

..Dean.. 06/27/2024