UPDATE: 11:30 am
Snow, arriving on schedule is becoming moderate to heavy across the I-39 corridor and moving into the Fox Valley. Snow will overspread much of the Chicago area through the early afternoon. The snow should diminish later this afternoon and turn to drizzle as warmer air moves in. Accumulations should range from 3 to 5 inches far north along the Wisconsin state line to and an inch or two far south.
Snow is currently heaviest from north-central Illinois east into the Fox Valley where visibilities have dropped below one mile. Expect rapidly deteriorating conditions across the Chicago area in the next few hours.
A Winter Weather Advisory for in general 2 to 4-inches of quick accumulating snowfall is in effect from 8AM to 4PM CST this Sunday for northeast Illinois into northwest Indiana (purple-shaded area on the headlined map). A fast-moving “clipper” low-pressure weather system will move from west to east across the Chicago area today, bringing brief heavy wet snowfall and possibly even a clap of thunder to a given location for a few hours and then moving off to the east. Snow accumulation will range from around 1 to 3-inches southernmost counties to 3 to 5-inches far north in counties adjacent to the Illinois-Wisconsin state line.
Snow will hit in westernmost sections of our area Fox River Valley/Interstate-39 corridor mid and late morning, spreading east – arriving in Chicago later morning/midday and in northwest Indiana midday/afternoon. Warmer above-freezing air will arrive immediately behind the snow, with a period of drizzle. The band of snow should be well to our east by mid/late afternoon.
Maps depicting the regional weather radar mosaic and visibility (a measure of snowfall intensity) along with a snowfall pictorial display prepared by the Chicago National Weather Service are shown below.
Regional Weather Radar Mosaic…
Current visibility (in miles)…
National Weather Service Pictorial…