What Happened to All the Rain?

Courtesy: Nat'l Center for Atmospheric Research

Last night at this time, I remember looking at a developing area of low pressure near the Tennessee/Kentucky state line and thinking, "Wow! This thing could dump almost an inch of rain in DeKalb and McHenry counties by Thursday morning." I also mentioned about a tenth to a quarter-inch of rain in Rockford. Instead, we've seen (as of this writing) 0.04" in Rockford, 0.27" in DeKalb, and 0.10" in Rochelle, and we probably will only see a few more hundredths of an inch overnight. Quite a bit less than I thought.

So what happened?

As the surface map at left shows, the main area of low pressure is now located in central Ohio. Last night at this time, it appeared that this low would be located about 100 miles to the west of its current location (near the Ohio/Indiana state line). This difference in track kept the heaviest rains to our east. For example, Chicago's O'Hare Airport has picked-up 0.68" of rain so far.