June 19, 2009 – update 2 – significant flash flooding possible

At 1:45 PM, rain was moving out of the area. A severe thunderstorm watch remains in effect until 3:00 PM, and is likely to be renewed through tonight.

Up to 3 inches of rain has fallen in the Chicagoland area (an exact reading will not be available until about 5:30 PM), and 3 inches more is possible through tonight. Six inches in 24 hours would rival last September’s flood, in which approximately 7.75″ fell within 12 hours.

A storm total of 4.5″ (or less) is more likely and would result in widespread street closures. A CoCoRaHS observer near the intersection of Lake Street and Bloomingdale Road reported 2.30″ of rain since 8:00 AM; it is likely that the Carol Stream area has received closer to 1 inch of rain instead of 3.

Stay tuned to the latest forecasts for more information, and this blog for more updates.