Tracking tomorrow's snow squall will kind of be like tracking a line of severe storms.
The high temperature on Wednesday could actually end up
occurring late morning immediately ahead of the much anticipated
strong arctic cold front expected to reach northwest
Illinois/Rockford area toward midday and quickly push across the
rest of Chicagoland into northwest Indiana through the
afternoon. This front will likely be accompanied by a period of
gusty snow showers and potentially a dangerous snow squall. Hi-
res guidance continues to suggest conditions will be conducive
for snow squalls. The RAP highlights well the potential for a
narrow axis of low-level frontogenesis to develop with the front
coinciding with steep low-level lapse rates along with a modest
3-hr surface pressure rise/fall couplet on either side of the
front. This could aid in enhancing wind gusts within this fgen
band locally up to 40-45 mph.
A lingering question remains when these "ingredients" all come
together, with the snow squall parameter increasing as the front
approaches the I-55/57 corridors into northwest Indiana. While
the Rockford area is not fully out of the woods, it is possible
coverage is lower west of the Chicago metro. If this scenario
plays out, the snow showers/squall may be developing as the
front moves into the Chicago metro. Regardless, all areas of
northern Illinois and northwest Indiana will want to be prepared
for a brief period of sharply reduced visibility in
snow/blowing snow and a quick coating on roadways resulting in
slick travel during the afternoon/evening commute.
To put this round of possible snow showers/squalls into
perspective compared to last week`s, surface temperatures will
already be below freezing (which were too warm last week for a
more robust initial snow squall with the front) and would
support snow readily accumulating on roadways. However, the
pressure gradient is not as strong, with peak wind gusts
currently expected to remain in the 40- 45 mph range versus the
55-60mph wind gusts observed last week. Nevertheless, multiple
hi-res models depict localized visibility reductions as low as
1/4 mile within these snow showers/squalls.