Mercury on roller coaster, high flood threat

Following quickly on the heels of the weekend deluge that put 2 to 4 inches of rain
across metropolitan Chicago and tossed in a few thunderstorms for good measure, a second and
considerably more vigorous weather system is roaring across the area today. It's bringing
a variety of weather conditions ranging from merely the inconvenient to the genuinely
dangerous. The day starts with chilly temperatures and plenty of rain. That's bad news
because area rivers and streams cannot handle much more water. Rain diminishes to scattered
afternoon showers, but moist and unstable Gulf air arrives in the afternoon, triggering a
round of active thunderstorms that will draw additional energy from 160-m.p.h. jet stream
winds. Temperatures jump into the 60s and severe storms are a possibility. Total
rainfall by evening: up to 2 inches.
ARCTIC BLAST ARRIVES LATE TUESDAY
And it won't be pleasant. Northwest winds gusting to 40 m.p.h. and temperatures plunging
40 degrees from evening readings near 60 degrees will drive wind-chill temperatures into
the single digits by dawn Wednesday.
--By Richard Koeneman, WGN Weather Center Meteorologist