768
ACUS01 KWNS 151242
SWODY1
SPC AC 151240

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0740 AM CDT Sat Jun 15 2024

Valid 151300Z - 161200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE CENTRAL
PLAINS/MIDDLE MO VALLEY AND NORTHERN HIGH PLAINS...

...SUMMARY...
Scattered severe thunderstorms with damaging winds and large hail
are possible from the late afternoon into the evening across the
Mid-Missouri Valley and also from eastern Montana to central North
Dakota. A couple of tornadoes could occur in eastern Nebraska and
western Iowa, with isolated significant severe hail and wind
possible across parts of the northern Great Plains.

...Eastern Nebraska to Iowa/northwest Missouri/southern Minnesota...

An MCS has largely weakened and trended downscale overnight as it
has progressed eastward across western Iowa/northwest Missouri, with
outflow extending from these areas west-southeastward into northeast
Kansas in proximity to a synoptic stationary/warm front. At least
one MCV is evident across the Siouxland vicinity early this morning,
with an additional MCV across west-central Nebraska.

The aforementioned front will move north-northeastward toward parts
of eastern Nebraska and western Iowa today. Diurnal heating will
support moderate to strong destabilization, both within a richly
moist environment near/north of the front, and within a somewhat
hotter and more well-mixed environment south/southwest of the front.
As a mid/upper-level trough (with multiple embedded vorticity
maxima) approaches the Middle Missouri Valley, and MLCINH diminishes
during the afternoon, isolated to widely scattered thunderstorm
development will be possible, especially across east/southeast
Nebraska and western Iowa and perhaps far northwest Missouri.

Along and immediately north of the front, favorable instability,
seasonably strong MCV-aided low-level flow, and a favorably veered
wind profile in the lowest 3 km AGL will be favorable for tornadic
supercells. Rather modest/somewhat backed mid-level flow may result
in a tendency for a cluster or complex HP storm mode with time. Any
supercells that can be sustained within this regime could pose a
tornado threat, in addition to hail and damaging-wind potential.
Some modest upscale growth will be possible later in the storm
evolution, which could result in a threat for damaging winds and
possibly a line-embedded tornado or two spreading east-northeastward
into parts of central Iowa and southern Minnesota this evening.

...Northern Great Plains including Eastern Montana and Dakotas...
A strong mid/upper-level shortwave trough will move over the Pacific
Northwest and northern Rockies later today, and approach the
northern High Plains tonight. A surface cyclone will deepen near the
Montana/Wyoming border vicinity during the day, and then move
northeastward across the western Dakotas vicinity this evening. Near
and east of the surface cyclone, MLCAPE is forecast to increase into
the 1500-2500 J/kg range from parts of eastern Montana into the
Dakotas, while stronger deep-layer flow/shear attendant to the
approaching shortwave will begin impinging on the warm sector by
late afternoon into the evening.

Storm development is expected by late afternoon from eastern
portions of Montana and Wyoming into the western Dakotas, with
development of one or more intense storm clusters possible by early
evening. Large to very large hail could accompany any sustained
supercells within this regime, especially from eastern Montana into
western North Dakota. Isolated significant severe gusts will also be
possible, especially in areas where stronger heating/mixing occurs,
and also in association with any more organized quasi-linear upscale
growth. A tornado or two could also occur, especially if any
supercell across western North Dakota can be sustained into the
evening, when an increase in low-level flow/SRH is expected.

...Southern High Plains...
Isolated to widely scattered thunderstorms are expected to develop
from mid-afternoon through early evening across parts of the
southern High Plains, including the Oklahoma/Texas Panhandles
southward to the Permian Basin/Transpecos. Moderate buoyancy and
marginally favorable deep-layer shear could support a couple of
modestly organized storms. Isolated severe wind gusts will be
possible within a generally hot and well-mixed environment, along
with some potential for hail.

..Guyer/Leitman.. 06/15/2024

$$