ACUS01 KWNS 200509
SPC AC 200507
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1207 AM CDT Wed Sep 20 2017
Valid 201200Z - 211200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM UPPER
MICHIGAN SOUTHWESTWARD INTO NORTHEAST KANSAS...
A few strong storms are possible from northeastern Kansas
northeastward to the Upper Peninsula of Michigan this afternoon and
...Synopsis and discussion...
A potent shortwave trough will quickly exit the northern
Plains/Upper MS Valley in a negatively tilted fashion with an
occluded front moving from northern MN into western Ontario. To the
south, a weak boundary will remain, extending from WI into eastern
KS. To the east of this front, a moist and unstable air mass will
exist with upper 60s dewpoints.
Scattered storms are likely to develop during the afternoon along
this front, especially over northern areas including WI, eastern IA,
and the U.P. of MI where convergence is strongest. However, forcing
for ascent will generally be weak as the primary shortwave trough
continues away from the region. Capping will be a concern for much
of the day, with only a narrow zone of storms expected near the
front. Marginally severe hail and wind are most likely, and a
brief/weak tornado cannot be ruled out given a moist boundary layer
and modest low-level shear.