738
ACUS02 KWNS 170553
SWODY2
SPC AC 170552

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1252 AM CDT Tue Sep 17 2024

Valid 181200Z - 191200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN 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 vertically stacked cyclone over eastern MT at 12Z Wednesday should
drift towards the ND/SK/MB border area. A mid-level jetlet of 50-60
kt winds at 500 mb should be confined within the dry slot, near the
ND/SD border area on Wednesday afternoon. A dryline should become
established from the eastern Dakotas to the southern High Plains.
Remnant convective outflows from overnight to decaying morning
convection are expected in the confined moist sector ahead of the
dryline. The primary cold front attendant to the cyclone should
gradually push east in the Dakotas and eventually merge with the
retreating dryline early morning Thursday.

Large-scale ascent ahead of the dryline appears nebulous for
surface-based storms during the afternoon to early evening.
Lingering outflows and areas of greater boundary-layer heating
should serve to focus isolated thunderstorm development. Guidance
varies greatly with placement of convection given the weak forcing
for ascent regime. But with a confined plume of moderate MLCAPE from
1500-2000 J/kg and 30-35 kt effective bulk shear, a conditional
lower-end supercell environment will exist. Relatively warm
mid-level temperatures will contribute to weaker lapse rates south
of the Mid-MO Valley, likely being a mitigating factor to more
robust updrafts where sustained storms can occur. The bulk of
guidance, outside of the 00Z GFS and RRFS, suggest sustained storm
development farther north will primarily be a result of low-level
warm theta-e advection Wednesday night. As such, severe storm
coverage will probably remain rather isolated.

..Grams.. 09/17/2024

$$