Mesoscale Discussion 0281
NWS Storm Prediction Center Norman OK
0611 AM CDT Fri Mar 22 2024
Areas affected...Northeast IA to the IL/WI border
Concerning...Heavy snow
Valid 221111Z - 221515Z
SUMMARY...A narrow band of heavy snow developing in north-central
Iowa should shift east across parts of northeast Iowa towards the Illinois-Wisconsin border through late morning. Rates of 1-2"/hr
should be expected, but may remain of relatively short-duration at
any one location.
DISCUSSION...The north side of a high-reflectivity convective plume
across central IA appears to have finally cooled enough to maintain
all snow to the surface, per recent surface observations and DOT
cameras. 03Z SREF probabilities and 00Z HREF snowbands guidance have
been highly insistent that a relatively narrow (around 25 miles
wide) heavy snow band should translate east, likely centered on the
US-20 corridor per observational trends. This suggests heavy snow
will be of relatively short duration at any one location, but
snowfall rates should easily reach 1-2"/hr given the focused 700-mb frontogenesis beneath the dendritic growth zone and the deep, nearly
isothermal layer just below freezing to the surface.