482
ACUS02 KWNS 171709
SWODY2
SPC AC 171708

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1208 PM CDT Tue Sep 17 2024

Valid 181200Z - 191200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF THE GREAT PLAINS...

...SUMMARY...
Isolated severe wind and hail are possible across a portion of the
Great Plains during the late afternoon and evening on Wednesday.

...Great Plains...

A stacked cyclone will slowly shift east/northeast from eastern MT
to southern SK/MB on Wednesday into early Thursday. At the surface,
a dryline will be oriented from the eastern Dakotas into
western/central NE, then southward across western KS and into the
OK/TX Panhandle vicinity. With time, a cold front will merge with
this feature on the northern end across the Dakotas during the
nighttime hours. Deep-layer south/southwesterly flow will remain
somewhat enhanced across the northern/central Plains toward the
Upper Midwest as the mid/upper trough shifts east. Around 30-35 kt
effective shear magnitudes are forecast along the extent of the
dryline. Meanwhile, surface dewpoints in the 60s will be maintained
ahead of the surface boundary in a persistent southerly low-level
warm advection regime. Midlevel temperatures are forecast to be
somewhat warm, precluding steeper lapse rates. Nevertheless,
1000-2000 J/kg MLCAPE is expected, with the greatest instability
expected near/north of the Mid-MO Valley.

Weakening convection may be ongoing Wednesday morning in the
vicinity of the Mid-MO valley, with areas of cloud cover extending
northward into MN. Where stronger heating occurs, low-level
convergence along the surface dryline and any remnant outflow
boundaries may focus thunderstorm development during the afternoon.
Large-scale ascent will be nebulous, with stronger forcing focused
near/north of the international border. Instability and shear will
decrease with southward extent into KS and the southern Plains. This
will limit coverage and intensity of convection to some degree.
Nevertheless, isolated strong to severe storms may pose a risk for
locally damaging gusts and hail.

Additional thunderstorms may develop overnight as the surface cold
front overtakes the dryline from the far eastern Dakotas into MN.
This activity will be driven by warm advection and likely be
elevated. Severe potential currently appears low beyond the 03-06z
time frame.

..Leitman.. 09/17/2024

$$