593
ACUS03 KWNS 170728
SWODY3
SPC AC 170728

Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0228 AM CDT Tue Sep 17 2024

Valid 191200Z - 201200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS IN A PART OF THE
UPPER MIDWEST...

...SUMMARY...
Scattered severe thunderstorms are possible from mid-afternoon to
early evening on Thursday across central to eastern Minnesota and
north-central Iowa.

...Upper Midwest...
A vertically stacked cyclone near the ND/SK/MB border should move
northeast over MB through the period. Predictability has increased
with the placement of the trailing cold front arcing south on
Thursday afternoon. In the mid-levels, modestly steepened lapse
rates should overspread this boundary within a belt of moderately
enhanced west-southwesterly flow. Given a confined plume of rich
boundary-layer moisture, a corridor of MLCAPE from 1500-2500 J/kg
should develop by mid-afternoon. Guidance consensus suggests
scattered thunderstorms should form along the MN portion of the cold
front towards mid to late afternoon amid an upper-level difluent
flow regime. More isolated activity may occur southward into the Mid
to Lower MO Valley.

A vertically veering wind profile with height should support
supercells with a primary initial risk of large hail. With
relatively modest upper-level winds and the expected coverage of
storms along the front, upscale growth into linear clusters will be
possible with a corresponding increase in damaging winds. A couple
tornadoes may occur given adequate low-level hodograph curvature and
the moist boundary layer.

The overall severe threat may diminish relatively rapidly after
sunset. With neutral mid-level height change as the MB cyclone pulls
away, in conjunction with progged weakening of 700-mb wind fields
after 00Z, convective intensity should wane. This will likely be
further aided by the confined buoyancy plume and drier airmass east.

..Grams.. 09/17/2024

$$