403
ACUS02 KWNS 151732
SWODY2
SPC AC 151730

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1230 PM CDT Sat Jun 15 2024

Valid 161200Z - 171200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
NORTHERN PLAINS INTO THE UPPER MISSISSIPPI VALLEY LATE SUNDAY...

...SUMMARY...
Scattered strong to severe storms are expected Sunday evening and
overnight from parts of the northern Plains into the upper
Mississippi Valley, with hail the primary risk.

...Synopsis...
A low-amplitude shortwave will likely extend from the Upper Midwest
southwestward into the Mid MO Valley early Sunday morning. This
shortwave is expected to quickly move northeastward across Upper MI
and into central Ontario. A stronger shortwave trough is forecast to
extend from southern Saskatchewan into the central Rockies early
Sunday morning, before then quickly progressing
eastward/northeastward and maturing into a mid-latitude cyclone over
Manitoba by Sunday evening. Surface low associated with this system
will gradually shift eastward from central Saskatchewan into
northern Manitoba, while an attendant cold front moves quickly
eastward/southeastward from central portions of the northern/central
Plains through the Upper Midwest. Northern/eastern portion of this
front will remain progressive as it moves through MN and into WI,
but the southern/western portion of the front is expected to stall
over the northern NE vicinity during the evening.

Lee troughing is expected to sharpen throughout the day as well,
with surface cyclogenesis likely across eastern CO by Sunday
evening. The surface pattern Sunday evening will likely feature a
low over northeast CO, with the stationary front extending
northeastward from this low across central NE to another weak low
near the NE/SD/IA border intersection. A cold front will extend
northeastward from this secondary low northeastward across southern
MN into northwest WI and then more north-northwestward into far
northwest Ontario. A lee trough will also extend southward from the
northeast CO low through eastern NM and the TX Trans Pecos.

Thunderstorm development is possible along all of these surface
boundaries, with highest coverage along the stationary front across
NE and SD into central/southern MN and northern WI. Additionally, a
weak wave is expected to slowly track northward/northwestward across
the Gulf of Mexico, bringing increased moisture to much of the Gulf
Coast. Afternoon/evening thunderstorms are expected across the
entire region, particularly across the central Gulf Coast closer to
the track of the wave.

...Upper Midwest into Upper MI early Sunday...
Elevated showers and thunderstorms will likely be ongoing early
Sunday morning ahead of the low-amplitude shortwave trough mentioned
in the synopsis. Expectation is for these storms to progress
northeastward into upper MI during the morning as the wave (and
associated warm-air advection) shift northeastward. Moderate
elevated buoyancy and shear will be in place, so a few storms may
become strong enough to produce isolated hail.

...Central High Plains across NE/SD into MN/WI Sunday afternoon into
Sunday night...
Temperatures along and south of the stationary front will likely
range from the mid to upper 90s during the afternoon from northeast
CO across southern and eastern NE. Dewpoints are expected to be in
mid to upper 60s across much of that same area. Temperatures in the
upper 80s/low 90s with dewpoints in the upper 60s to low 70s
expected farther east across MN ahead of the cold front. Afternoon
thunderstorm development appears unlikely along the stationary
front, with warm mid-level temperatures and the lack of stronger
large-scale ascent keeping the airmass capped. There is a low chance
that initiation could occur along the cold front in MN, particularly
across northern MN where greater large-scale ascent is anticipated.
Any storms that do form along the cold front could produce large to
very large hail. However, uncertainty regarding development
precludes higher than 5% probabilities with this outlook.

A strengthening low-level jet will likely aid in the development of
predominantly elevated convection to the north of the stationary
front after 00Z. Development is possible along the length of the
front, but will likely begin in the eastern WY/western SD/NE
Panhandle vicinity. Strong buoyancy and shear will support hail with
these elevated storms. Despite the elevated character to these
storms, a few stronger gusts may be able to reach the surface,
particularly near the stationary front.

...Central/Southern High Plains Sunday afternoon into evening...
Strong diurnal heating and deep boundary-layer mixing is anticipated
along the lee trough from far eastern CO southward into the Texas
Trans-Pecos. Isolated thunderstorm development is possible along
this boundary amid low-level convergence and airmass
destabilization. High cloud bases and relatively modest shear should
support outflow-dominant structures, and strong gusts are possible
with any deeper, more persistent updrafts.

..Mosier.. 06/15/2024

$$