Latest meso-scale discussion highlights area of developing heavy snow across northern Illinois and the Chicago area

Snowfall across northern  Illinois has been light since it began earlier this evening with current totals less than two inches. However, latest trends indicate an area of heavy snow with accumulation rates of about 1 inch an hour setting up across northern Illinois generally north of the I-80 corridor. Look for increasing snowfall with lowering visibilities during the overnight hours with the heaviest snow arriving in the Chicago area before midnight


Mesoscale Discussion 0061 NWS Storm Prediction Center Norman OK 0907 PM CST Thu Feb 08 2018

Areas affected…Portions of IA…southern WI…and northern IL Concerning…Heavy snow Valid  9pm-3am CST


SUMMARY…A narrow band of moderate to heavy snow will likely produce snowfall rates around 1 inch per hour through the early morning. DISCUSSION…A low-amplitude shortwave trough present over NE/KS will move eastward across the Upper Midwest overnight. Large-scale lift ahead of this trough has promoted a broad area of light to moderate snow extending from eastern SD to southern WI/northern IL. A strengthening southwesterly low-level jet across southern IA is focusing a low-level baroclinic zone across central IA as of 9pm CST. Related frontogenetic forcing should remain centered around 850 mb, and a narrow west-to-east oriented band of moderate to heavy snow has recently developed across central IA on the nose of the low-level jet. Snowfall rates around 1 inch per hour in this band will likely occur through the remainder of the evening and continue through the overnight hours. As the shortwave trough develops eastward, the moderate to heavy snow band will shift eastward into southern WI and northern IL (including the Chicago metro), mainly after 11pm CST.